EP2553117A1 - Methods for detecting raman scattering using aromatic compounds comprising phosphate and at least one non-laser light source - Google Patents

Methods for detecting raman scattering using aromatic compounds comprising phosphate and at least one non-laser light source

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Publication number
EP2553117A1
EP2553117A1 EP11714460A EP11714460A EP2553117A1 EP 2553117 A1 EP2553117 A1 EP 2553117A1 EP 11714460 A EP11714460 A EP 11714460A EP 11714460 A EP11714460 A EP 11714460A EP 2553117 A1 EP2553117 A1 EP 2553117A1
Authority
EP
European Patent Office
Prior art keywords
raman
aromatic compound
detection
sample
phosphate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11714460A
Other languages
German (de)
French (fr)
Inventor
Samar Kumar Kundu
Charles Lester Ginsburgh
Neal Arthur Siegel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sword Diagnostics Inc
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Sword Diagnostics Inc
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Filing date
Publication date
Application filed by Sword Diagnostics Inc filed Critical Sword Diagnostics Inc
Publication of EP2553117A1 publication Critical patent/EP2553117A1/en
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/34—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase
    • C12Q1/42—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase involving phosphatase
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/02—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving viable microorganisms
    • C12Q1/04—Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/26—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving oxidoreductase
    • C12Q1/28—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving oxidoreductase involving peroxidase
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering

Definitions

  • the present disclosure generally relates to the field of biological diagnostic equipment and testing methods.
  • PCR Polymerase Chain Reaction
  • LCR Ligase Chain Reactions
  • Specificity of detection methods can be enhanced by using immunological techniques.
  • medical diagnostics use antibody-based techniques to provide specificity in the detection of biological components of a sample.
  • Antibodies developed to specific compounds are known to have high affinity and specificity for these components.
  • antibodies are difficult to detect and typically require chemical modification with labels or tags to enhance detection.
  • antibody detection is prone to interference from other material in the sample including the sample matrix, wash components, and other chemical and biological agents.
  • current techniques lack sensitivity at low
  • concentrations or numbers of antibodies i.e., low concentrations or numbers of targeted biological components.
  • Raman light scattering techniques have been used in the past to detect specific chemical components. Raman scattering is a basic property of the interaction of light with molecules. When light hits a molecule it can cause the atoms of the molecule to vibrate. This vibration will then change the energy of additional light scattered from the molecule. This scattered light has characteristics that are measurable and are unique to the structure of the vibrating molecule. Thus, a Raman spectrum can be used to uniquely identify a molecule.
  • Raman spectroscopy has several advantages over existing detection methods, including simple application and production of quantifiable data.
  • Raman spectroscopy by itself lacks specificity and sensitivity for the detection of biological organisms and components.
  • dedicated laser-based Raman detectors are expensive, are not easily available, and are limited to a single wavelength. Therefore, there is a need in the art for reagents and methods that allow for the practical use of Raman scattering in the detection of organisms and biological components.
  • the present disclosure is directed to methods that use the
  • Raman scattering a detector comprising at least one non-laser- based light source, and biological labeling techniques to identify and quantify biological organisms and components with higher sensitivity and specificity than prior art techniques.
  • One embodiment of the disclosure is a method for detecting the activity of at least one enzyme in a sample comprising:
  • Another embodiment is a method for detecting the activity of an enzyme in a sample comprising:
  • Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
  • Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
  • Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
  • Another embodiment is a method for detecting at least one target in a sample comprising:
  • Another embodiment is a method for detecting at least one target in a sample comprising:
  • kits for detecting at least one enzyme activity comprising:
  • kits for detecting at least one enzyme activity comprising:
  • the Raman-active product is detected using resonance Raman spectroscopy. In another embodiment, the Raman-active product is detected using scattered light.
  • the at least one non-laser-based light source is a spectrophotometer capable of detecting Raman scattering using a fluorescence detection channel.
  • the at least one amine-containing compound comprises:
  • X is H, NH 2 , CI, Br, nitro, or benzyl
  • Y is H, CI, Br, or nitro
  • Z is H, benzyl, or NH 2 .
  • X is NH 2 , and Y and Z are H.
  • X is CI, and Y and Z are H.
  • X is Br, and Y and Z are H.
  • X is nitro, and Y and Z are H.
  • X and Z are H and Y is CI.
  • X and Z are H and Y is Br.
  • X and Z are H and Y is nitro.
  • X and Z are benzyl and Y is H.
  • X and Z are NH 2 and Y is H.
  • the at least one amine-containing compound comprises:
  • the at least one amine-containing compound comprises:
  • the at least one aromatic compound comprises:
  • W, X, Y, and Z are H or OH.
  • Y is OH and X, Y and Z are H.
  • W is OH, and X, Y and Z are H.
  • W and X are OH, and Y and Z are H.
  • W and Y are OH, and X and Z are H.
  • W and Z are OH and X and Y are H.
  • the at least one aromatic compound comprises:
  • X, Y, and Z are H or OH.
  • X is OH and Y and Z are H.
  • X and Y are OH and Z is H.
  • X and Z are OH and Y is H.
  • Z is OH and X and Y are H.
  • the at least one aromatic compound comprises:
  • X and Y are H or OH.
  • X is OH and Y is H.
  • X is H and Y is OH.
  • the at least one aromatic compound comprises:
  • X and Y are H or OH.
  • X is OH and Y is H.
  • X is H and Y is OH.
  • the at least one amine-containing compound comprises an aromatic amine.
  • the aromatic amine comprises ortho-phenylenediamine, meta-phenylenediamine, or para- phenyleneamine:
  • the at least one aromatic compound comprises:
  • X is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, P0 4 , or COOH;
  • Y is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, or COOH;
  • the at least one aromatic compound comprises:
  • X is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, P0 4 , or COOH;
  • Y is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, or COOH;
  • Z is H, OH, CI, Br, NH 2 , S0 3 H, P0 4 , or COOH.
  • the at least one aromatic compound comprises:
  • X is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, P0 4 , or COOH;
  • Y is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, or COOH.
  • the at least one aromatic compound comprises:
  • X is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, P0 4 , or COOH;
  • Y is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, or COOH.
  • the at least one aromatic compound comprises:
  • the at least one amine-containing compound is chosen from 4-aminoantipyrene, 5-aminosalicyclic acid, and o-phenylenediamine;
  • the at least one aromatic compound is chosen from 2-hydroxybenzyl alcohol, 4- chloro-3,5-dimethylphenol, 2-naphthol, 4-hydroxy-4-biphenyl-carboxylic acid, 5,7- dichloro-8-hydroxyquinoline, 4-chloro-1-naphthol, phenol, 4-amino-1 -phenyl-1- phosphate, 4-hydroxy-1-naphthyl-1-phosphate, 4-amino-1-naphthyl-1-phosphate, hydroquinone diphosphate, and 4,5 dihydroxy-naphthelene-2,7-disulfonic acid; and the at least one electron-donating compound is chosen from an organic hydrogen peroxide, urea hydrogen peroxide, and hydrogen peroxide (H 2 0 2 ).
  • the at least one electron-donating compound is a hydrogen peroxide.
  • the hydrogen peroxide is chosen from an aromatic hydrogen peroxide, urea hydrogen peroxide and hydrogen peroxide (H 2 0 2 ).
  • the at least one enzyme is a peroxidase or a phosphatase.
  • the phosphatase is alkaline phosphatase.
  • the alkaline phosphatase is conjugated to an antibody, an avidin moiety, a streptavidin moiety, a biotin moiety, or a biotin-binding protein.
  • the at least one aromatic compound is 2- hydroxybenzyl alcohol
  • the at least one amine containing compound is 5- aminosalicyclic acid
  • the at least one electron-donating compound is urea hydrogen peroxide
  • the at least one enzyme is a peroxidase
  • the mixture is incubated in the presence of a base.
  • the base is sodium hydroxide.
  • the oxidizing agent is sodium metaperiodate.
  • the mixture further comprises biotin.
  • the ligand is chosen from a receptor and an antibody. In another embodiment, the ligand is an antibody.
  • the at least one target is an organism.
  • the organism is chosen from a bacteriophage, a bacterium, including E. coli, Listeria, Salmonella, Vibrio, Camphelbacter, and Staphylococcus, and a virus such as HIV, Hepatitis, Adenovirus, Rhino virus, and Human papilloma virus.
  • the target is a component of an organism.
  • the component is a protein.
  • the protein is an interleukin.
  • the interleukin is IL-2.
  • the protein is chosen from C-Reactive protein, Tumor Necrosis Factor Receptor II, and Human Cardiac Troponin I.
  • the target is a component of an organism chosen from amino acids, nucleic acids, nucleotides, metabolites, carbohydrates, hormones, and metabolic intermediates.
  • Figure 1 is a flow chart of a typical prior art immunoassay technique (ELISA) for the detection of biological organisms or components.
  • ELISA immunoassay technique
  • Figure 2 is a diagram of an embodiment of the disclosed apparatus.
  • Figure 3 is a flow chart of an embodiment of the disclosed technique for the detection of biological organisms and/or components.
  • Figure 4 is a block diagram of the enzyme system for converting chemical components to a Raman-active compound.
  • Figure 5 is a flow chart of a technique for choosing light frequencies to excite specific target molecules.
  • Figure 6 is an illustration of a micro-fluidic channel designed to detect Raman-active compounds.
  • Figure 7 is an illustration of an array of micro-fluidic channels such as might be incorporated into a custom integrated circuit.
  • Figure 8 plots Raman spectra from an enzyme-linked immunoassay for a pathogenic bacteria, Listeria, utilizing an antibody linked to peroxidase and with shift numbers (cm "1 ) plotted on the abscissa and signal magnitudes plotted on the ordinate (arbitrary units) for a sample containing Listeria (a) and a sample not containing Listeria (b).
  • Figure 9 A plots Raman spectra measured at 3260 cm '1 produced using Raman Reagent formulation A-1 in three experiments, while Figure 9 B plots SQR Raman spectra measured at 3500-4000 cm "1 produced using Raman Reagent A-1 in the three experiments.
  • Figure 10 plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent A-1 (diamonds), and Raman Reagent A-2 (triangles) and A-3 (squares).
  • Figure 1 1 plots SQR Raman spectra measured at 3500-4000 cm "1 produced using Raman Reagent formulation A-1 (diamonds), and Raman Reagent A-2 (squares and triangles).
  • Figure 12 plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent formulation A-2 (squares) and A-2 with fresh HPRO in BSA diluent (diamonds).
  • Figure 13 plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent B-1 (diamonds), B-2 (squares), B-3 (triangles), and B-4 ("Xs").
  • Figure 4 plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent B-2 (squares) and B-2 with fresh HPRO in BSA diluent (diamonds).
  • Figure 15 A plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent C-1 while Figure 15 B plots the corresponding SQR Raman spectra measured at 3500-4000 cm “1 .
  • Figure 16 A plots Raman spectra measured at 3260 cm “1 produced using Raman Reagent D-1 while Figure 16 B plots the corresponding SQR Raman spectra measured at 3500-4000 cm “1 .
  • Figure 17 plots SQR Raman spectra measured at 3500-4000 cm '1 produced using Biotin-ASA-UP and ASA-UP.
  • Figure 18 is a bar graph showing the relative sensitivity of the reagents tested.
  • Figure 19 is a plot of the SQR Raman spectra measured at 3500- 4000 cm “1 and absorbance spectrum measured at 450 nm in IL-2 immunoassays using BASH-UP and TMB.
  • Figure 20 A is a plot of an absorbance spectrum for a BASH-UP reaction
  • Figure 20 B is an absorbance spectrum for an OPD reaction.
  • Figures 21 A and 21 B are plots of fluorescence spectra of BASH-UP and OPD reactions without peroxidase
  • Figures 21 C and 21 D are plots of fluorescence spectra of BASH-UP reactions with peroxidase.
  • Figures 22 A and 22 B are plots of fluorescence spectra of OPD reactions without peroxidase
  • Figures 22 C and 22 D are plots of fluorescence spectra of OPD reactions with peroxidase.
  • Figures 23 A and 23 B are plots of Raman signals produced by BASH-UP and OPD reactions, respectively.
  • Figure 24 A is a plot of Raman signals over time for an OPD reaction without peroxidase
  • Figures 24 B-E are plots of Raman signals over time for OPD reactions with decreasing amounts of peroxidase.
  • Figures 25 A-D are plots of SQR spectra over time for OPD reactions.
  • Figure 26 A is a plot of Raman signal of benzoquinone and Figure 26 B is a plot of Raman signal of pyrogallol, both figures showing enhanced Raman signal upon adding sodium hydroxide.
  • Figure 26 A (a) is a plot of Raman signal for benzoquinone with NaOH added
  • Figure 26 A (b) is a plot of Raman signal for benzoquinone with no NaOH.
  • Figure 26 B (a) is a plot of Raman signal for pyrogallol with NaOH added
  • Figure 26 B (b) is a plot of pyrogallol with no NaOH.
  • Figure 27 A is a plot of Raman signal of 1 ,4-naphthaquinone
  • Figure 27 B is a plot of Raman signal of 1 ,4-iminonaphthaquinone, both figures illustrating a dependence on periodate and sodium hydroxide.
  • Figure 27 A (a) is a plot of Raman signal of 1 ,4-naphthaquinone with no periodate or NaOH.
  • FIG. 27 (b) is a plot of Raman signal of 1 ,4-naphthaquinone with periodate but no NaOH.
  • Figure 27 A (c) is a plot of Raman signal of 1 ,4-naphthaquinone with no periodate but with NaOH.
  • Figure 27 A (d) is a plot of Raman signal of 1 ,4-naphthaquinone with periodate and NaOH.
  • Figure 27 B (a) is a plot of Raman signal of 1 ,4- iminonaphthaquinone with NaOH.
  • Figure 27 B (b) is a plot of Raman signal of ,4- iminonaphthaquinone in borate buffer.
  • Figure 27 B (c) is a plot of Raman signal of 1 ,4-iminonaphthaquinone with periodate and NaOH.
  • Figure 27 B (d) is a plot of Raman signal of 1 ,4-iminonaphthaquinone with periodate but no NaOH.
  • Figure 28 A is a logarithmic plot of Raman spectral values at 3300 cm " recorded for 4-aminophenylphosphate as a function of alkaline phosphatase- antibody conjugate concentration with the addition of oxidizing agent, while Figure 28 B shows the linear plot.
  • Figure 29 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase conjugate concentration ranging from 0-1000 ng/mL with the addition of oxidizing agent, while Figure 29 B shows the range 0-10 ng/mL.
  • Figure 29 A (a-f) show Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline phosphatase conjugate: (a) 1000 ng/ml, (b) 100 ng/ml,
  • Figure 29 B shows Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline phosphatase conjugate: (a) 10 ng/ml, (b) 1 ng/ml, (c) 0 .1 ng/ml, (d) 0.01 ng/ml; and (e) 0 ng/ml.
  • Figure 30 A is a logarithmic plot of Raman spectral values at 3300 cm "1 recorded for 4-aminophenylphosphate as a function of alkaline phosphatase concentration, while Figure 30 B shows the linear plot.
  • Figure 31 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase concentration ranging from 0-2500 mU/mL, while Figure 31 B shows the range 0-25 mU/mL.
  • Figure 31 A (a-f) shows Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline
  • phosphatase (a) 2500 mU/mL; (b) 250 mU/mL; (c) 25 mU/mL; (d) 2.5 mU/mL; (e) 0.25 mU/mL; and (f) 0 mU/mL.
  • Figure 31 B (a-e) shows Raman spectra of 4- aminophenylphosphate as a function of alkaline phosphatase concentration: (a) 25 mU/mL; (b) 2.5 mU/mL; (c) 0.25 mU/mL; (d) 0.025 mU/mL; and (e) 0 mU/mL.
  • Figure 32 shows Raman spectra of peroxidase detected using a fluorescent microplate reader.
  • Figure 33 shows Raman spectra of peroxidase detected using a fluorescent microplate reader.
  • Figure 34 shows the Raman spectral response of peroxidase at different emission wavelengths detected using a fluorescent microplate reader.
  • Figure 35 shows dose response curves of peroxidase detected using a single lens Raman optics based reader (Raman SV) and a fluorescent microplate reader at 680 nm.
  • Figure 36 shows dose response curves of peroxidase detected using a single lens Raman optics based reader (Raman SQR) and a fluorescent microplage reader at 680 nm.
  • Figure 37 shows dose response curves of TNF-a detected using a single lens Raman optics based reader (Raman SV) and a fluorescent microplate reader at 680 nm.
  • Figure 38 shows dose response curves of TNF-a detected using a single lens Raman optics based reader (Raman SQR) reader and a fluorescent microplate reader at 690 nm.
  • Figure 39 shows dose response curves of TNF-a detected using a TMB colometric assay and a fluorescent microplate reader at 690 nm.
  • Figure 40 shows the response of alkaline phosphatase on Tecan Infinite® M1000 multimode reader at different wavelengths.
  • Figure 41 shows the results of the scan with alkaline phosphatase.
  • Figure 42 shows the results from alkaline phosphatase from calf intestine for 45 minute reading at excitation wavelength 550 nm and emission at 580.
  • Figure 43 shows the results from alkaline phosphatase from E. coli for 45 minute reading at excitation wavelength 550 nm and emission at 580 nm.
  • diagnostics pathogen detection, forensics, and homeland security require the rapid and specific identification of biological organisms, such as contaminating bacteria, and biological components such as proteins, DNA, or other genetic material.
  • biological organisms such as contaminating bacteria, and biological components such as proteins, DNA, or other genetic material.
  • biological components such as proteins, DNA, or other genetic material.
  • a common assay to identify a bacterium in a sample is an
  • immunoassay which relies on detecting an antibody bound to the bacterium.
  • the antibody is labeled and the presence of the antibody is detected by assaying for the presence of the label.
  • the antibody is conjugated to an enzyme, and the presence of the antibody-enzyme conjugate is detected by assaying for enzymatic activity.
  • a commonly used assay that employs an enzyme- antibody conjugate is the enzyme linked immunosorbant assay (ELISA).
  • ELISA enzyme linked immunosorbant assay
  • enzymatic activity can be measured by incubating the enzyme-antibody conjugate in the presence of reactants that are converted by the enzyme into products which can be detected through colorimetric, fluorogenic, and
  • chemiluminescent means suffers from several deficiencies such as limited dynamic range, limited sensitivity, and interference from background.
  • Raman spectroscopy has several advantages over these methods, it generally cannot be used in combination with commonly used colorimetric, fluorogenic, and chemiluminscent reagents because they typically do not produce useful Raman spectra.
  • the colorimetric reagents 3,3', 5,5'- tetramethelene benzidine (TMB), and azinobisethlybenzthiazolinesulfonic acid (ABTS) do not produce Raman spectra useful for detecting organisms.
  • reagents that produce Raman-active products useful for detecting organisms are desired, including reagents that can be used in immunoassay formats employing enzyme-antibody conjugates.
  • Reagents useful for detecting a bacterium in an immunoassay format using Raman scattering have certain desired characteristics.
  • the reagents should produce a Raman signal in an area of the Raman spectrum that does not already have background signal produced by the bacterium.
  • the Raman signal produced by the reagents should be quantifiable, allowing for detection over a wide range of concentrations.
  • Certain embodiments of the present disclosure are based in part on the discovery that certain amine-containing compounds can be used in
  • Certain embodiments of the present disclosure are also based in part on the discovery that certain combinations and amounts of the reagents of the disclosure produce superior sensitivity. This sensitivity can be further enhanced through use of the Single Quantifiable Result (SQR) method of the disclosure, which employs multiple wavenumber spectroscopic analyses.
  • SQL Single Quantifiable Result
  • Raman-active products may be detected using a non-laser- based light source, such as a fluorescence-detection device, a laser-based light source, or both.
  • a non-laser- based light source such as a fluorescence-detection device, a laser-based light source, or both.
  • Certain embodiments of the present disclosure are also based in part on the discovery that the colorimetric reagent o-phenylenediamine (OPD) can be used to produce Raman-active products, in contrast to other colorimetric reagents. OPD can be used in combination with Raman scattering to measure real-time kinetics of enzyme activity.
  • OPD o-phenylenediamine
  • Additional embodiments of the present disclosure are based in part on the discovery that compounds having at least one phosphate group can be used as phosphatase substrates to produce Raman-active products, or precursors to Raman- active products.
  • the phosphatase substrates may be aromatic compounds that may be enzymatically dephosphorylated in the presence of a phosphatase to form the corresponding phenols or aminophenols. The phenols and aminophenols may then autooxidize or become oxidized by the addition of an oxidizing agent to generate the corresponding Raman-active quinones or iminoquinones.
  • the phosphatase substrates may be used in an immunoassay format.
  • the phosphatase may be alkaline phosphatase.
  • the precursors to Raman-active products may be converted to Raman-active products by exposure to a base.
  • the base may be NaOH.
  • Antibody means an immunoglobulin or a part thereof, and encompasses any polypeptide comprising an antigen-binding site regardless of the source, method of production, and other characteristics.
  • the term includes for example, polyclonal, monoclonal, monospecific, polyspecific, humanized, single-chain, chimeric, synthetic, recombinant, hybrid, mutated, and CDR-grafted antibodies.
  • a part of an antibody can include any fragment which can still bind antigen, for example, an Fab, F(ab') 2 , Fv, scFv.
  • the origin of the antibody is defined by the genomic sequence irrespective of the method of production.
  • amino acids of any length
  • polymeric form of amino acids of any length can include naturally-occurring amino acids, coded and non-coded amino acids, chemically or biochemically modified, derivatized, or designer amino acids, amino acid analogs, peptidomimetics, and depsipeptides, and polypeptides having modified, cyclic, bicyclic, depsicyclic, or depsibicyclic peptide backbones.
  • the term includes single chain protein as well as multimers.
  • amino acid refers to monomeric forms of amino acids, which can include naturally-occurring amino acids, coded and non-coded amino acids, chemically or biochemically modified, derivatized, or designer amino acids, amino acid analogs, peptidomimetics, and depsipeptides.
  • polynucleotide refers to polymeric forms of nucleotides of any length.
  • the polynucleotides can comprise deoxyribonucleotides, ribonucleotides, and/or their analogs or derivatives.
  • nucleotide refers to monomeric nucleotides and includes deoxyribonucleotides, ribonucleotides, and/or their analogs or derivatives.
  • ligand refers to a molecule that binds to another molecule, including a receptor.
  • Light source refers to any source of energy that falls within the electromagnetic spectrum.
  • Light sources include, but are not limited to, light bulbs, lasers, diodes, masers, and gas-discharge lamps including neon lamps, xenon lamps, xenon flash lamps, and mercury-vapor lamps.
  • the present disclosure can be practiced in various formats.
  • the format is an immunoassay.
  • a target biologic is first bound to an antibody that is attached to a solid surface.
  • Unbound components of the test sample are then optionally washed away leaving only the bound biologic/antibody combinations, which can be detected by Raman light scattering.
  • a target biologic is first bound to an antibody, or an antibody-enzyme conjugate. This biologic/antibody or
  • biologic/antibody-enzyme combination reacts with a substrate compound, such as an aromatic organic compound having at least one phosphate group, via the antibody portion of the biologic/antibody or biologic/antibody-enzyme combination.
  • a substrate compound such as an aromatic organic compound having at least one phosphate group
  • the substrate compound then further oxidizes into a Raman-active product.
  • quantification of the target biologic is thus achieved by detection of the Raman-active product.
  • the combination of the new reactant(s) with the biologic/antibody combination can now be detected using Raman scattering of light.
  • examples of such reactants include, but are not limited to the reagents listed in Table 1.
  • the Raman detection methods can use chemicals that interact with the biologic without the antibody.
  • the Raman-based methods can be applied to many immunoassays including, but not limited to, the detection of Human IL-1 1 , Rat C- reactive Protein, Soluble Tumor Necrosis Factor Receptor II, and Human Cardiac Troponin I.
  • the Raman-based methods can be applied to the detection of variety of organisms and components.
  • bacteriophage are detected.
  • bacteria including E. coli, Listeria, Salmonella, Vibrio, Camphelbacter, and Staphylococcus and detected.
  • viruses such as HIV, Hepatitis, Adenovirus, Rhino virus, Human papilloma virus are detected.
  • components including proteins, amino acids, nucleic acids, nucleotides, metabolites, hormones, and metabolic intermediates are detected.
  • SQL Single Quantifiable Result
  • Raman spectra can be analyzed by obtaining a Single Quantifiable Result (SQR).
  • SQR number is the difference between a Raman spectra corresponding to a targeted analyte measured in a sample, and any background Raman signal/spectra observed in the measurement process.
  • the steps of the SQR process are shown in Table 2.
  • spectra for the background of the sample (Negative Control) and for the samples being investigated (Test Samples) are measured.
  • the square root of the "Sum of the Squares of the Differences” is calculated ("Square Root of the Sum of the Squares of the Differences"). This value is designated as the SQR value.
  • the SQR process can include an assessment of whether the Raman signals from the sample and background are appropriate (i.e., "valid") and sufficient to indicate the presence of the targeted analyte in the sample (i.e., "positive value”).
  • the SQR process may be performed manually or with designed computer software.
  • the Raman signals for multiple wave numbers are tabulated for the background and test spectra. In one embodiment, every 2 nd wave number is tabulated for both the background and test spectra. In another embodiment, every wave number is tabulated for both the background and test spectra. In one embodiment the range of wave numbers is from 2000 to 4000 cm "1 .
  • the range of wave numbers is from 3500 to 4000 cm ⁇
  • the difference between the test signal and background signal is determined for a range of wave numbers and the square of this difference is stored.
  • the sum of the squares is determined, and the square root of this sum is the SQR value.
  • the Raman value of the background sample ("Negative Control") at a wave number, for example, 3260 cm "1 should run as expected (above a minimum and below a maximum value). This determination will aid in ensuring that a correct sample was run as the negative control, and that the assay was run correctly.
  • the SQR value of the positive control should not run below an expected value. This will aid in ensuring that a correct sample was run as the positive control, and that the assay was run correctly.
  • the "Sum of the Differences" for each test sample should not run below an expected value.
  • the SQR method can be carried out manually or with the aid of a computer.
  • One embodiment of the disclosure is a computer bearing machine operable language for the calculation of the SQR.
  • the Raman-active compounds of the invention may be detected using an instrument with a traditional laser-based light source.
  • Such instruments include, for example, a Raman Systems INC QE 65000 Raman Detector and a Lambda Solutions model PS-1 detector.
  • the Raman- active compounds may be detected using an instrument with a non-laser-based light source.
  • the non-laser-baesd light source may comprise a high-intensity light source.
  • the high-intensity light source may comprise a xenon lamp, a xenon flash lamp, a neon lamp, or a mercury-vapor lamp.
  • Suitable instruments comprising a non-laser-based light source include, for example, fluorescence detectors such as, for example, Tecan Infinite 200, Tecan Infinite ® 200 PRO, and Tecan Infinite ® M1000.
  • embodiments of the present disclosure can be implemented on a micro-fluidic channel (or well) integrated circuit using micro or nano-fabrication technology in which the binding partner is immobilized in one or more micro-fluidic channels in a custom integrated circuitry which would also include equipment to detect the Raman spectra generated by the methods of the invention.
  • Such an implementation could detect single biological components such as pathological bacteria, proteins or genetic material.
  • an object of certain embodiments of the present disclosure is to have a system for the detection of target biological organisms or components that utilizes a combination of chemical interactions including binding with a final step of Raman light scattering.
  • Another object of certain embodiments of the present disclosure is to have a system for the detection of target inorganic or organic components that utilizes a combination of chemical interactions including binding with a final step of Raman light scattering.
  • Another object of certain embodiments of the present disclosure is to combine an immunoassay with detection using Raman light scattering.
  • Still another object of certain embodiments of the present disclosure is to increase sensitivity of detection by the use of chemical reactants that produce resonance Raman light scattering.
  • Yet another object of certain embodiments of the present disclosure is to have an integrated circuit design with micro-fluidic channels or wells which can perform the combination of binding and Raman light scattering measurements.
  • FIG. 1 is a flow chart of a typical prior art immunoassay technique (ELISA) ( 0) for the detection of biological organisms or components.
  • the process begins by step (11) of preparing the liquid sample that includes the target biologic.
  • the sample can be prepared by pre-enrichment in a growth medium such as half-Frasier's broth or other suitable microbial growth medium.
  • a liquid sample for testing may be obtained from any liquid source. Solid material may be immersed in an appropriate liquid solution and potential target organism or molecules placed in solution and then sampled in the liquid.
  • the prepared liquid sample is combined (or mixed) with a binding partner that has been attached to a solid surface.
  • Typical binding partners include antibodies,
  • bacteriophage and bacteriophage proteins.
  • plastic microtiter plates latex beads or magnetic microparticles may be used.
  • Other solid supports such as nitrocellulose, filter paper, nylon and other plastics may also be used.
  • the antibody/biologic combination is then incubated in step (13) to allow time for the biologic and antibody to bind together. Once this has occurred the combined binding partner/biologic is decanted (poured off) and washed to remove unbound biologies and other unwanted materials. New reactants are added in step (15) to enhance the sensitivity of the mixture to detection of signal molecules by various methods.
  • step (13) The mixture containing the bound binding partner/biologic and new reactants is the incubated in step (13) to allow time for the reaction to occur.
  • the reaction part of the process (10) is complete and step (16) of measuring the molecules produced or included in steps (11 ) through (15) inclusive can be performed. If additional reactants are required, steps (14), (15) and (13) may be repeated one or more times in succession until the appropriate signal molecules are present.
  • step (17) The measurement of the signal molecule(s) provides a quantitative result that can then be analyzed and compared in step (17) to a known set of calibrated responses of known concentrations of the target biologic. This comparison results in step (18) which is the quantified result and associated report of the concentration of the target biologic in the sample prepared in step (1 1).
  • process (10) of FIG. 1 has been associated with the detection of a biological organism or component, the process (10) is also applicable to the detection of many types of molecules to which antibodies or other binding partners can react.
  • FIG. 2 is a diagram of an embodiment of a laser-based Raman detection sub-system (20).
  • a laser (21) produces a laser beam (22) which is focused by the focusing optics (23) into a focused laser beam (24) which hits the target sample (25).
  • the backscattered light (26) from the sample (25) is focused into the beam (28) by the focusing optics (27).
  • the beam (28) is directed into the
  • the laser (21 ) is typically a continuous wavelength (CW) laser with output in the visible range.
  • CW continuous wavelength
  • Focusing optics (23) and (27) include mirrors, lenses, irises, shutters, diffraction gratings, and/or polarizers.
  • the target sample (25) may be liquid, gas or solid and in certain embodiments, the target sample would use a liquid or precipitated solid.
  • the spectrometer (30) spatially separates the scattered light based on wavelength.
  • An example of a usable spectrometer for the present disclosure is the Lambda Solutions model PS-1.
  • the detector (31) measures the amplitude of the light spatially separated by the spectrometer (30) and converts this into an electrical signal (analog or digital). In certain embodiments, the detector would provide the electrical signal using a standardized computer interface such as RS-232, USB, parallel, IEEE 1394.
  • An example of a usable detector (30) for the present disclosure is a Raman Systems INC QE 65000 Raman Detector or a Lambda Solutions model PS-1 detector.
  • the personal computer (40) can be any desktop or laptop PC with an appropriate interface to the detector (31) and software designed to analyze, store and/or print the spectrum of the backscattered light (26) received by the spectrometer (30).
  • FIG. 3 is a flow chart of an embodiment of the present disclosure (30) for the detection of biological organisms and/or components.
  • the process begins by step (31 ) of preparing the liquid sample that includes the target biologic.
  • the sample may be prepared by pre-enrichment in a growth medium such as half-Frasier's broth or other suitable microbial growth medium.
  • a liquid sample for testing may be obtained from any liquid source. Solid material may be immersed in an appropriate liquid solution and potential target organism or molecules placed in solution and then sampled in the liquid.
  • the prepared liquid sample is combined (or mixed) with an antibody that has been attached to a solid surface.
  • plastic microtiter plates, latex beads or magnetic microparticles may be used.
  • step (33) The antibody/biologic combination is then incubated in step (33) to allow time for the biologic and antibody to bind together. Once this has occurred the combined antibody/biologic is decanted (poured off) and washed to remove unbound biologies and other unwanted materials. New reactants are added in step (35) to enhance the sensitivity of the mixture for detection of the Raman light scattering. Examples of such reactants are listed in Table 1.
  • step (33) The mixture containing the bound antibody/biologic and new reactants is the incubated in step (33) to allow time for the reaction to occur.
  • step (36) of measuring Raman light scattering from Raman-active molecules produced by steps (31 ) through (35) inclusive can be performed. If additional reactants are required, steps (34), (35) and (33) may be repeated one or more times in succession until the appropriate Raman-active molecules are present.
  • step (37) The measurement of Raman light scattering can then be analyzed and compared in step (37) to a known set of calibrated responses of known concentrations of the target biologic. This comparison results in step (38) which is the quantified result and associated report of the concentration of the target biologic in the sample prepared in step (31 ).
  • Listeria may be measured in an (enzyme-linked immunosorbant assay) ELISA format. 100 microliters of various concentrations of bacteria; 100,000, 50,000, 25,000, 12,500, 6,250 and 0 colony forming units (cfu) per ml are added to microwells coated with anti-Listeria antibodies. After an incubation period between 30 and 60 minutes at 37°C, the wells are decanted and washed with a mild detergent solution three times. 100 ⁇ of peroxidase-conjugated anti- Listeria antibodies are added to the well and incubated for 1 to 4 hours at 37°C. The wells are decanted and washed with a mild detergent solution three times.
  • FIG 4 is a block diagram for a chemical conversion system (40) which uses an enzyme for converting chemical components to a Raman-active compound.
  • one or more reactants designated (41), (42) and (43) are mixed with a biological catalyst (44).
  • the biological catalyst (44) may be an enzyme specific for metabolizing the reactants provided or RNA structures designed to interact with the one or more reactants (41 ), (42), and (43).
  • a conversion or combination of the reactants occurs in the reaction (45) and a measurable product (46) is formed.
  • the reactants and those in Table 4 are mixed together in the presence of peroxidase (44) and urea hydrogen peroxide (UP) (43).
  • Additional reactants that may produce Raman-active products can be used in the disclosed methods, such as compounds comprising a least one hydroxyl group and one amino group at positions 1 and 4 in a benzene or naphthalene.
  • Such compounds include:
  • X is H, NH 2 , CI, Br, nitro, or benzyl
  • Y is H, CI, Br, or nitro
  • Z is H, benzyl, or NH 2 .
  • X is NH 2 , ancTY and Z are H.
  • X is CI, and Y and Z are H.
  • X is Br, and Y and Z are H.
  • X is nitro, and Y and Z are H.
  • X and Z are H and Y is CI.
  • X and Z are H and Y is Br.
  • X and Z are H and Y is nitro.
  • X and Z are benzyl and Y is H.
  • X and Z are NH 2 and Y is H.
  • Such compounds also include:
  • X is H, OH, CI, Br, or nitro (N0 2 ).
  • Such compounds also include:
  • X is H, CI, Br, or N0 2 .
  • Additional compounds that may produce Raman-active products in the disclosed methods include compounds comprising at least two hydroxyl functions in 1 , 2 or 1 , 4 positions in a benzene or naphthalene ring.
  • Such compounds include:
  • W, X, Y, and Z are H or OH.
  • Y is OH and X, Y and Z are H.
  • W is OH, and X, Y and Z are H.
  • W and X are OH, and Y and Z are H.
  • W and Y are OH, and X and Z are H.
  • W and Z are OH and X and Y are H.
  • Such compounds include polyphenols, such as:
  • X, Y and Z are H or OH.
  • X is OH and Y and Z are H.
  • X and Y are OH and Z is H.
  • X and Z are OH and Y is H.
  • Z is OH and X and Y are H.
  • Additional compounds that may produce Raman-active products in the disclosed methods include compounds comprising hydroxymethlene (-CH 2 OH) group in a benzene or naphthalene. Inclusion of additional hydroxyl groups at positions 1 , 4, and 6 may enhance the Raman scattering.
  • Such compounds include:
  • X and Y are H or OH.
  • X is OH and Y is H.
  • X is H and Y is OH.
  • Such compounds also include:
  • X and Y are H or OH.
  • X is OH and Y is H.
  • X is H and Y is OH.
  • Such compounds also include aromatic amines, including compounds comprising ortho-phenylenediamine, meta-phenylenediamine, and para- phenyleneamine:
  • Such compounds also include 2,4-diaminobenzyl alcohol, 2-amino- 1-naphthol, and 4-aminoantipyrene.
  • the product of the reaction (45) may be used as a quantitative or qualitative reporting molecule for the reaction and as such may be used as a probe for the presence of specific biological targets if conjoined with, for example, specific antibodies or biological or chemical binding partners.
  • Certain compounds may spontaneously form Raman-active products upon exposure to air ("auto-oxidation"). Such compounds are ill-suited for use in certain assay formats, such as ELISA, because they exhibit Raman signals without being acted on by an enzyme.
  • the present disclosure provides modified versions of these reactants that allow for their use in Raman scattering-based assays.
  • hydroxyl groups present in compounds of the disclosure which may spontaneously oxidize, can be modified with phosphate groups to prevent spontaneous oxidation.
  • these compounds further expand the types of compounds that can be used in the methods presently disclosed.
  • reactants comprising phosphate gropus may be oxidized by the addition of an oxidizing agent.
  • the present disclosure also provides methods for using Raman scattering based on detecting phosphatase activity.
  • Additional reactants that produce Raman-active products can be used in the presently-disclosed methods, such as compounds comprising at least one phosphate group.
  • Such compounds include aromatic organic compounds
  • phosphate group for example compounds comprising benzene or naphthalene rings having at least one phosphate group as a substituent.
  • additional substituent groups such as carboxyl, amine, chlorine, bromine, nitro and/or other functional groups may enhance the Raman scattering of the Raman-active product.
  • Such compounds according to the present disclosure may, for example, have functional groups that are ortho (1 ,2) and/or para (1 ,4) to each other.
  • the aromatic organic compounds comprising at least one phosphate group have the following structure:
  • X is H, OH, CI, Br, N0 2 , NH 2 , S0 3 H, or COOH; Y is H, OH, CI, Br, N0 2 , S0 3 H or NH 2 ; W is OH or P0 4 and Z is H, OH, CI, Br, S0 3 H, P0 4 or NH 2 .
  • X, Y, and Z are H.
  • X is OH, and Y and Z are H.
  • X is N0 2
  • Y and Z are H.
  • X is CI, and Y and Z are H.
  • X is Br, and Y and Z are H.
  • X is COOH, Y is OH, and Z is NH 2 .
  • X is CI, Y is OH, and Z is NH 2 .
  • X is S0 3 H, Y is OH, and Z is NH 2 .
  • such compounds may undergo catalytic dephosphorylation by reaction with alkaline phosphatase (ALP), and then oxidize to form a Raman-active quinone compound.
  • ALP alkaline phosphatase
  • Such compounds oxidized in the ortho (1 ,2) or para (1 ,4) position including, for example, catechol (1 , 2-dihydroxy-benzene), hydroquinone (1, 4- dihydroxybenzene), and pyrogallol (1 , 2, 3- trihydroxybenzene), may undergo rapid oxidation in air to generate the corresponding quinone.
  • the Raman scattering of the quinone product is enhanced upon treatment with a base such as strong sodium hydroxide (NaOH) solution.
  • a base such as strong sodium hydroxide (NaOH) solution.
  • This signal enhancement may be pH-dependent (i.e., NaOH dependent) such that the Raman scattering decreases upon addition of an acid, and increases upon addition of a base (restoring Raman scattering enhancement).
  • NaOH sodium hydroxide
  • auto-oxidation and Raman scattering enhancement upon addition of NaOH has been observed for catechol, pyrogallol, and 1 ,2,4-benezenetriol, which have the following structures:
  • the aromatic organic compounds comprising at least one phosphate group further comprise at least one amine group, and have the following structure:
  • X is H, OH, CI, Br, N0 2 , S0 3 H, P0 4 or NH 2
  • Y is H, OH, CI, Br, N0 2 , S0 3 H or NH 2
  • Z is H, OH, CI, Br, S0 3 H, P0 4 or NH 2 .
  • X, Y, and Z are H.
  • X is OH, and Y and Z are H.
  • X is N0 2 , and Y and Z are H. In another embodiment, X is CI, and Y and Z are H. In another embodiment, X is Br, and Y and Z are H.
  • such compounds may undergo catalytic dephosphorylation by reaction with alkaline phosphatase (ALP), then oxidize to form the corresponding Raman-active iminoquinone compound.
  • ALP alkaline phosphatase
  • the iminoquinones may generate enhanced Raman scattering that may be quantitated.
  • Another phosphate-containing compound, 4- hydroxynaphthylphosphate is known to undergo catalytic dephosphorylation to yield 1 , 4-dihydroxynaphthalene. This is then rapidly oxidized by air to form 1 , 4- naphthaquinone, which has been used in an amperometric immunoassay with high detection sensitivity of detection (Masson et al., Anal. Chim. Acta, 402, 29-35, 1999). Naphthyl compounds substituted with functional groups in the 1 , 2, or both positions may undergo similar rapid oxidation in air to generate the corresponding quinones.
  • the aromatic organic compounds comprising at least one phosphate group further comprise at least one hydroxyl group and have the following structure:
  • X is H, OH, CI, Br, N0 2 , S0 3 H, P0 4 or NH 2 and Y is H, OH, CI, Br, N0 2 , S0 3 H or NH 2 .
  • X and Y are H.
  • X is OH and Y is H.
  • X is N0 2 and Y is H.
  • X is CI and Y is H.
  • X is Br and Y is H.
  • Another phosphate-containing compound, 4- aminonaphthylphosphate, is known to undergo catalytic dephosphorylation to yield 4-amino-1 -naphthol. This is then rapidly oxidized by air to form 1 , 4- iminonaphthaquinone, which has been used in amperometric immunoassays with high sensitivity of detection (Masson et al., Talanta, 64, 174-180, 2004).
  • the aromatic organic compounds comprising at least one phosphate group further comprise at least one amine group and have the following structure:
  • X is H, OH, CI, Br, N0 2 , S0 3 H or P0 4 ; and NH 2 and Y is H, OH, CI, Br, N0 2 , S0 3 H or NH 2 .
  • X and Y are H.
  • X is OH and Y is H.
  • X is N0 2 and Y is H.
  • X is CI and Y is H.
  • X is Br and Y is H.
  • such compounds may undergo catalytic dephosphorylation to yield the corresponding amino-naphthol, which can further oxidize to form a Raman-active iminonaphthaquinone.
  • the reaction is exemplified below:
  • the aromatic organic compounds comprising at least one phosphate group have the following structure: wherein X, and Z are each H ,0H, S0 3 H, NH 2 , P0 4 or Y and W are each H , OH, SO3H, or NH 2 .
  • X, Y, Z, and W are H.
  • X is H
  • Y, Z and W are OH.
  • X and Y are H
  • Z and W are OH.
  • FIG. 5 is a flow chart of the technique (50) for choosing one or more light frequencies to excite specific target molecules for detection of the Raman-active products.
  • a Raman-active product (51) such as the product (46) produced by the reaction (45) of FIG. 4, is a chemical that possesses a structure which is Raman- active.
  • the absorbance spectrum of the product (51) is measured in step (52) using a technique such as absorbance or transmittance spectrophotometry.
  • step (53) one or more wavelengths are identified at which the product (51) absorbs light as seen in the spectrum measured in step (52).
  • a light source that emits light at a wavelength corresponding to one of the one or more wavelengths identified in step (53) is then selected.
  • Such wavelengths can be in the visible range, ultraviolet range or infra-red range. For example, for the Listeria detection reaction (30) described for FIG. 3, the wavelength selected is 532 nm.
  • step (55) the light source chosen in step (54) is used to irradiate the Raman-active product created in step (51). This will confirm that there is significant Raman scattering of the Raman-active product created in step (51) to provide adequate signal for detection.
  • the invention may be practiced using detectors other than non-single lens Raman optics detectors, such as fluorescence detectors.
  • FIG. 6 is an illustration of a micro-fluidic channel (60) designed to detect Raman-active compounds.
  • a source liquid (or gas) sample (61 ) including the target biological organisms or components flows through the channel (62).
  • the target biological organisms or components will react and be bound to the reactant(s) attached to the active surface (64).
  • Light (68) from a light source (65) produces Raman scattered light (69) which is detected by the photodetector (66).
  • the photodetector is designed to measure one or more specific wavelengths which correspond to the Raman scattering of the combined reactant(s) and biological organism or component. It is also envisioned that instead of binding the biological organism or component to the surface (64), the reactant(s) may be released from the surface and the Raman-scattering light source (65) and detector (66) may be located downstream from the surface.
  • FIG 7 is an illustration of an array of micro-fluidic channels (70) designed to detect Raman-active compounds.
  • One or more source liquid (or gas) samples (71 A), (71 B) through (71 N) which include the target biological organisms or components flow through the channels (72A), (72B) through (72N).
  • the target biological organisms or components will react and be bound to the reactant(s) attached to the active surfaces (74A), (74B) through (74N).
  • Light, (78A) through (78N) from the light sources, (75A) through (75N), produce Raman-scattered light, (79A) through (79N), which is detected by the photodetectors (76A) through (76N).
  • the photodetectors are designed to measure one or more specific wavelengths which correspond to the Raman scattering of the combined reactant(s) and biological organisms or components bound to the surfaces.
  • Figure 8 depicts Raman spectra obtained from an enzyme-linked immunoassay for the pathogenic bacteria Listeria utilizing the two-component BASH- UP chemistry, an enzyme-linked antibody, and Raman detection procedure described below utilizing the following buffers and reagents:
  • the Raman signal was generally stable for ⁇ 1 hour or longer.
  • the first component in the chemistry (BASH) contained 2-hydroxy benzyl alcohol (0.02 mg/ml), 5-amino salicylic acid (0.1 mg/ml), 0.1 % Tween-20, and ascorbic acid (1 ⁇ g/ml) in the Working Saline Buffer (pH 6.0).
  • the second component (UP) contained urea peroxide adduct (1 mg/ml) the working Saline Buffer (pH 6.0) including EDTA (1 mM). These formulations maintained activity when refrigerated out of direct light for more than one month. Mixing the two components at a ratio of 1 UP to 10 BASH created a working solution of BASH-UP that was generally stable for one working day.
  • Method A HRPO dilutions were made to measure 1000 pg to 0.0125 pg per 50 ⁇ sample in phosphate-buffered saline (PBS) containing 0.1% bovine serum albumin (BSA) at pH 7.4. 50 ⁇ HRPO sample per dilution was added to 200 ⁇ TMB reagent and allowed to react for 15 or 30 minutes at which time 200 ⁇ stop-solution (KPL Laboratories) was added. Absorbance was measured at 450 nm for each sample.
  • PBS phosphate-buffered saline
  • BSA bovine serum albumin
  • Method B HRPO dilutions were made to allow 1000 pg to 0.0125 pg per 50 ⁇ sample in PBS at pH 7.4. 50 ⁇ HRPO sample per dilution was added to 200 ⁇ ABTS reagent and allowed to react for 15 or 30 minutes at which time 200 ⁇ stop solution (1% SDS in water) was added. Absorbance was measured at 405 nm for each sample.
  • the limit of detection of HRPO for TMB was 8 pg/ml and the dynamic range was 5 to 5000 pg/ml.
  • the limit of detection was 32 pg/ml and the dynamic range was 32 to 5000 pg/ml.
  • EXAMPLE 3 FLUOROGENIC AND CHEMILUMINESCENT ASSAYS OF HRPO
  • AnaSpec Fluorogenic kit utilizes ADHP (10-acetyl-3,7- dihydroxyphenoxazine) to analyze peroxidase in solution whereby ADHP is oxidized in the presence of peroxidase and hydrogen peroxide.
  • the oxidized product of ADHP (resozufin) gives pink fluorescence that can be measured at the emission wavelength of 590 nm with the excitation wavelength of 530-560 nm.
  • An overdose of peroxidase in the assay will further convert the fluorescent resorufin to non- fluorescent resozurin to yield reduced fluorescent signal.
  • HRPO dilutions were made to allow detection of 1 ,000,000 pg to 0.0625 pg per 50 ⁇ sample were prepared in PBS at pH 7.4. The procedure was the same as described earlier for TMB and ABTS assays, and two methods were used.
  • Method A ADHP Reagent and Hydrogen Peroxide were prepared per manufacturer's instructions. 500 ⁇ of peroxidase solution was added to 500 ⁇ ADHP reagent in a 1.5 ml plastic microcuvette. The reaction mixture was gently mixed, and incubated at room temperature for 30 min without light exposure. The fluorescent signal was measured for emission at 590 nm with excitation at 550 nm on an Ocean Optics Fluorescent Spectrometer.
  • Method B Similar to Method A except 400 ⁇ of each of peroxidase and ADHP reagents were used.
  • the sensitivity (lowest limit of detection) of the AnaSpec ADHP fluorescent assay was found to be 12.5 pg/ml of HRPO.
  • the assay range was linear from 250 pg/ml to 0 pg/ml of HRPO.
  • Molecular Probes Fluorogenic assay kit employs Amplex Red (10- acetyl-3,7-dihydroxyphenoxazine), which is similar to AnaSpec ADHP assay.
  • Amplex Red (10- acetyl-3,7-dihydroxyphenoxazine)
  • the oxidized end product of the assay with peroxidase and hydrogen peroxide is resorufin.
  • the assay claim is 1 X 10-5 U/ml, equivalent to 10 pg/ml (1 X 10-5 ml).
  • HRPO dilutions made to allow detection of 1 ,000,000 pg to 0.0625 pg per 50 ⁇ sample were prepared in PBS, pH 7.4. Amplex Red Reagent and
  • Hydrogen Peroxide were prepared per Manufacturer's instructions. 400 ⁇ of peroxidase solution was added to 400 ⁇ ADHP reagent in a 1.5 ml plastic microcuvette. The reaction mixture was gently mixed and incubated at room temperature for 30 min in the dark. The fluorescent signal was measured at 590 nm with excitation at 550 nm on an Ocean Optics Fluorescent spectrometer at 30 min and 35 min.
  • the sensitivity (lowest limit of detection) of the Molecular Probes Amplex Red Fluorescent assay was found to be 25 pg/ml of HRPO.
  • the assay range was linear from 250 pg/ml to 0 pg/ml of HRPO.
  • LumiGLO is a luminol-based chemiluminescent substrate designed for use with peroxidase-labeled reporter molecules.
  • HRPO converts luminol to an excited intermediate dianion. This dianion emits light on return to its ground state. After reaction with HRPO conjugate, the light emission from LumiGLO reaches maximum intensity within 5 minutes and is sustained for approximately 1 - 2 hours.
  • Table 7 compares the detection limits from different Raman Reagent A formulations, showing the increase in sensitivity provided by the SQR method.
  • Table 9 compares the detection limits from several different Raman reagent B formulations, showing the increase in sensitivity provided by the SQR method.
  • Raman Reagent A-1 500 pg/ml ASA; 20 pg/ml HBA; 20 pg/ml AA
  • Raman Reagent B-3 250 pg/ml ASA; 25 pg/ml CDMP
  • HRPO dilutions made to allow 1000 pg to 0.0125 pg per 50 pi sample were prepared in PBS at pH 7.4. 50 pi HRPO sample per dilution was added to 150 ⁇ reagent and allowed to react for 30 minutes. 50 ⁇ of 0.5 N NaOH was then added. After incubation for 30 minutes, Raman spectra were recorded using a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector. Data were analyzed using SQR. Results from representative experiments appear in Tables 14- 18.
  • Results in Figure 17 show that the Biotin-ASA-UP combination provides a sensitive assay that can detect as low as 0.00625 pg sample.
  • ASA-UP without HBA also enables detection as low as 2 pg of HRPO.
  • Raman Reagent A increasing ASA from 100 to 250 or 500 ⁇ g/ml
  • Reagent B increasing ASA from 100 to 250 or 500 ⁇ g/ml
  • Biotin-ASA provide ultra sensitive peroxidase assays, compared to Reagent A-1 and Reagent C formulations.
  • Raman-based assays provide highly sensitive detection of Peroxidase in solution, which is shown graphically in Figure 18.
  • ASA by itself provides very good sensitivity, which is increased by the addition of CDMP, Biotin and even NAP.
  • the limit of detection of peroxidase was 3.9 and 4.4 pg/ml when 500 ⁇ g/ml of ASA was used and Raman signal analyzed with wave number 3,300 cm "1 and SQR, respectively.
  • the limit of detection was 2.3 and 1.9 when the Raman signal was analyzed with wave number 3,300 cm "1 and SQR, respectively
  • the Amplex Read Peroxidase assay is linear between 25 and 250 pg/50 ⁇ of sample (per vendor's claim) and the assay is able to detect as low as 1x10-5 U/ml.
  • the Sigma HRPO used in the current study had an activity of 1080 U/mg solid. On this basis, 1x10 "5 U/ml HRPO is equivalent to 10 pg/ml (0.5 pg/50 ⁇ ).
  • Table 18 summarizes a representative comparison of Raman-based detection and detection by absorbance, chemiluminescence, and fluorescence.
  • Urea-Peroxide 1000 ug/mL which contains 360 ug/mL Hydrogen Peroxide
  • the reagent was dissolved in 10 mM phosphate buffered saline with 2 mM EDTA, pH 6.0 (PBS-EDTA) and filtered through a sterile 0.45 micron cellulose nitrate filter and was stored in an amber colored polyethylene bottle at 2-8 °C.
  • Raman substrate was prepared by mixing Reagent A and Reagent B in a volume ratio of 9:1 prior to use. The substrate should be used in the same of preparation.
  • EXAMPLE 11 ABSORBANCE. FLUORESCENCE, AND RAMAN DETECTION OF
  • OPD o-phenylenediamine
  • Emission spectra were collected using 12 second integration and a box width of 30. Emission spectra are shown in Figures 21 A-D.
  • the fluorescence emission spectra of both the negative (0 pg/ml peroxidase) and reactive (2,000 pg/ml peroxidase) BASH reactions were similar ( Figures 21 A and B), with a low level of inherent fluorescence.
  • the OPD reaction fluorescence spectra were similar ( Figures 22 A-D).
  • EXAMPLE 12 RAMAN SENSITIVITY OF OPD-PEROXIDASE REACTIONS AND MEASUREMENTS OF ENZYME KINETICS
  • Raman spectra were collected in the range 0-4000 cm "1 with a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector equipped with a 532 nm laser.
  • the compounds examined were benzoquinone, pyrogallol, 1 ,4- naphthaquinone, and 1 ,4-iminonaphthaquinone.
  • Figure 26 A shows Raman spectra of benzoquinone as a function of adding strong NaOH solution 0.5 N where the added NaOH causes enhanced Raman signal. This enhancement was found to be reversible, where addition of an acid decreased the signal and re-addition of NaOH again increased the signal.
  • Figure 26 B shows Raman spectra of pyrogallol (1 ,2,3-trihydroxybenzene) also as a function of added NaOH. Pyrogallol exemplifies an aromatic (phenyl) structure hydroxylated in the ortho (1 ,2) position.
  • Figure 27 A shows Raman spectra of 1 ,4-naphthaquinone as a function of both NaOH and periodate.
  • Figure 27 B similarly shows Raman spectra of 1 ,4-iminonaphthaquinone. These plots indicate that such compounds undergo rapid auto-oxidation to generate Raman signal.
  • 1 ,4-naphthaquinone (Figure 27 A) shows very high signal with or without periodate without the presence of NaOH. The spectral pattern changes with the addition of NaOH and showed reduced signal.
  • 1 ,4- iminonaphthaquinone shows enhanced Raman signal without periodate in the presence of NaOH.
  • This compound shows reduced signal with periodate in the presence of NaOH, possibly due to further oxidation of imino function in this compound.
  • the Raman signal of 1 ,4-iminoquinone could not be generated without NaOH ( Figure 27 B (d and e).
  • EXAMPLE 14 EXEMPLARY PHOSPHATASE-BASED RAMAN IMMUNOASSAY REAGENTS AND PROCEDURES
  • Goat anti-human IgG H+L alkaline phosphatase conjugate (KPL) (contains protein stabilizer and
  • Enzyme Storage Buffer 10 mM TRIS buffer, 50 mM KCI, 1 mM MgCI 2 , 0.1 mM ZnCI 2 , 50% glycerol, pH 8.2.
  • Coating Buffer 50 mM sodium carbonate-bicarbonate buffer, pH 9.4
  • Blocking Buffer 50 mM TRIS buffer, pH 8.0 with 2% BSA (bovine serum albumin) with 0.05% Tween 20, pH 8.0
  • Assay Buffer 50 mM TRIS buffered Saline with 0.1% BSA and 1 mM MgCI 2 , pH 9.0
  • Wash Buffer 50 mM TRIS buffered saline with 0.05% Tween 20, pH 8.0
  • Procedure A An immunoassay of 4-aminophenyl phosphate is prepared as follows:
  • Procedure B Immunoassays of hydroquinone diphosphate, 4- hydroxynaphthyl phosphate, and 4-aminonaphthyl phosphate are prepared as follows:
  • Blocking Empty the plate. Add 200 ⁇ of blocking buffer and incubate for 1 hour at room temperature.
  • the plate can be stored at 4 ° C for
  • Washing Wash the plate with 300 pL of wash buffer per well 5 times. Blot the plate after the last wash on a stack of paper towels.
  • Antigen A per well (standards as well as samples to be tested). Incubate for 1 hour at room temperature on a plate shaker. Samples should be freshly diluted in the assay buffer before adding to the plate.
  • alkaline phosphatase conjugated antibody specific to Antigen A in assay buffer to approximately 1
  • EXAMPLE 16 COLORIMETRIC DETECTION OF ALKALINE PHOSPHATASE CONJUGATE WITH OXIDIZING AGENT
  • Alkaline phosphatase was analyzed via colorimetry using p- nitrophenylphosphate as the substrate.
  • EXAMPLE 17 RAMAN DETECTION OF ALKALINE PHOSPHATASE
  • Alkaline phosphatase was analyzed via Raman spectroscopy using 4- aminophenylphosphate as the substrate, with oxidizing agent (sodium
  • “Positive” refers to samples whose mean Raman signal recorded at 3300 cm “1 was greater than the negative mean signal recorded at 3300 cm “1 (+ 2 SD).
  • Figure 28 A is a logarithmic plot of Raman spectral values at
  • Figure 29 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase conjugate concentration ranging from 0-1000 ng/mL with the addition of oxidizing agent, while Figure 29 B shows the range 0-10 ng/mL. The limit of detection was approximately 0.25 ng/mL.
  • EXAMPLE 18 COLORIMETRIC DETECTION OF ALKALINE PHOSPHATASE WITHOUT OXIDIZING AGENT
  • Alkaline phosphatase was analyzed via colorimetry using p- nitrophenylphosphate as the substrate.
  • Alkaline phosphatase was analyzed via Raman spectroscopy using 4- aminophenylphosphate as the substrate, without oxidizing agent.
  • Figure 30 A is a logarithmic plot of Raman spectral values at 3300 cm "1 recorded for 4-aminophenylphosphate as a function of alkaline phosphatase concentration; Figure 30 B shows the linear plot.
  • Figure 31 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase concentration ranging from 0-2500 mU/mL, while Figure 31 B shows the range 0-25 mU/mL. The limit of detection was approximately 1 mU/mL.
  • EXAMPLE 20 RAMAN DETECTION OF FREE PEROXIDASE USING A SINGLE LENS RAMAN OPTICS BASED DETECTOR AND A FLUORESCENCE-BASED DETECTOR
  • HRPO Horseradish peroxidase
  • Negative control reaction components with 0 pg/ml HRPO in 50 mM Imidazole, 50 mM phosphate, and 3 mM EDTA at pH 6.5 containing 0.1% BSA.
  • the plate was incubated at room temperature for 30 minutes. 6. The plate was read in the indicated detectors.
  • Tecan fluorescence detector set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
  • the analytical limit of detection was estimated as the concentration read from the fitted 4PL curve corresponding to the mean signal of the negative control + 2 standard deviation (SD) units (associated with the negative measurement). This evaluation included: evaluation of the shape of the standard curve, estimation of the LOD, and graphical estimation of standard curve shift due to Raman detection.
  • the Raman signal was measured as: (i) the matnitude of the shifted backscatter signal at a single Raman shift number at 3,200 cm “1 (Raman SV); (ii) a sample to negative ratio of the measured values (S/N); or (iii) an "area under the curve” measurement designated as "single quantifiable result" or "SQR” value. The latter value quantitates the difference between the Raman spectra of a reactive sample and its respective background (negative sample) over a specified Raman shift range.
  • EXAMPLE 21 RAMAN DETECTION OF A PEROXIDASE-BASED ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) USING A SINGLE LENS RAMAN OPTICS BASED DETECTOR AND A FLUORESCENCE-BASED DETECTOR
  • M1000 set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
  • TMB tetramethyl benzidnine
  • EXAMPLE 23 RAMAN DETECTION OF FREE ALKALINE PHOSPHATASE USING A SINGLE-LENS-RAMAN-OPTICS-BASED DETECTOR AND A
  • 4-aminoaphthylphosphate (4-ANP) synthesized according to the procedure in Masson et al., Talanta, 64:174-180 (2004).
  • M1000 set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
  • the analytical limit of detection was estimated as the concentration read from the fitted 4PL curve corresponding to the mean signal of the negative control + 2 standard deviation (SD) units (associated with the negative measurement). This evaluation included: evaluation of the shape of the standard curve, estimation of the LOD, and graphical estimation of standard curve shift due to Raman detection.
  • the Raman signal was measured as: (i) the magnitude of the shifted backscatter signal at a single Raman shift number at 1583 cm “1 (Raman SV); (ii) a sample to negative ratio of the measured values (S/N); or (iii) an "area under the curve” measurement designated as "single quantifiable result” or "SQR" value (1500- 2501 cm-1).
  • the latter value quantitates the difference between the Raman spectra of a reactive sample and its respective background (negative sample) over a specified Raman shift range.
  • Figure 40 shows the response of alkaline phosphatase on Tecan fluorescence detector at different wavelengths. The data indicated highest signal at 580 nm.
  • Table 24 shows the mean Tecan signal at 580 nm TABLE 24
  • Tables 25 and 26 show the results derived from the same microtiter plate on a Raman reader.
  • EXAMPLE 24 RAMAN DETECTION OF FREE ALKALINE PHOSPHATASE USING A SINGLE-LENS-RAMAN-OPTICS-BASED DETECTOR AND A

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Abstract

The present disclosure provides systems for the rapid and sensitive detection of organisms and molecules in samples. Reactants that produce Raman-active products are used in combination with Raman light scattering and a detection system that utilizes at least one non-laser-based light source, such as a fluorescence detection system. Such compounds may comprise phosphates permitting the detection of phosphatases and phosphate-based enzyme assays, such as immunoassays and DNA-based assays. The present disclosure can also be used to measure enzyme-kinetics.

Description

METHODS FOR DETECTING RAMAN SCATTERING USING AROMATIC COMPOUNDS COMPRISING PHOSPHATE AND AT LEAST ONE NON-LASER
LIGHT SOURCE
[001] This application claims priority to U.S. Provisional Application No. 61/318,377, filed March 28, 2011 , which is incorporated herein by reference.
DESCRIPTION OF THE INVENTION
Field of the Invention
[002] The present disclosure generally relates to the field of biological diagnostic equipment and testing methods.
Background of the Invention
[003] There are currently many areas needing systems to detect biological organisms or components (e.g., proteins, DNA, or other genetic material). These areas include: food safety, medical and veterinary diagnostics, pathogen detection, forensics, and homeland security. Current detection methods include
immunochemistry and molecular biology, and biological techniques such as
Polymerase Chain Reaction (PCR) and Ligase Chain Reactions (LCR). These methods and techniques are often limited in accuracy, specificity, and sensitivity. Moreover, such methods often require extensive sample preparation, such as the isolation and purification of nucleic acids.
[004] Specificity of detection methods can be enhanced by using immunological techniques. For example, medical diagnostics use antibody-based techniques to provide specificity in the detection of biological components of a sample. Antibodies developed to specific compounds are known to have high affinity and specificity for these components. However, antibodies are difficult to detect and typically require chemical modification with labels or tags to enhance detection. Unfortunately, antibody detection is prone to interference from other material in the sample including the sample matrix, wash components, and other chemical and biological agents. Moreover, current techniques lack sensitivity at low
concentrations or numbers of antibodies (i.e., low concentrations or numbers of targeted biological components).
[005] Raman light scattering techniques have been used in the past to detect specific chemical components. Raman scattering is a basic property of the interaction of light with molecules. When light hits a molecule it can cause the atoms of the molecule to vibrate. This vibration will then change the energy of additional light scattered from the molecule. This scattered light has characteristics that are measurable and are unique to the structure of the vibrating molecule. Thus, a Raman spectrum can be used to uniquely identify a molecule.
[006] Raman spectroscopy has several advantages over existing detection methods, including simple application and production of quantifiable data. However, Raman spectroscopy by itself lacks specificity and sensitivity for the detection of biological organisms and components. In addition, dedicated laser-based Raman detectors are expensive, are not easily available, and are limited to a single wavelength. Therefore, there is a need in the art for reagents and methods that allow for the practical use of Raman scattering in the detection of organisms and biological components.
[007] The present disclosure is directed to methods that use the
combination of Raman scattering, a detector comprising at least one non-laser- based light source, and biological labeling techniques to identify and quantify biological organisms and components with higher sensitivity and specificity than prior art techniques.
SUMMARY OF THE INVENTION
[008] One embodiment of the disclosure is a method for detecting the activity of at least one enzyme in a sample comprising:
a) preparing a mixture comprising the sample and:
i. (optionally) at least one aromatic compound;
ii. at least one amine-containing compound; and
iii. at least one electron-donating compound;
b) incubating the mixture to form at least one Raman-active product; and
c) detecting the at least one Raman-active product using at least one non-laser-based light source.
[009] Another embodiment is a method for detecting the activity of an enzyme in a sample comprising:
a) preparing a mixture comprising the sample and:
i. optionally at least one aromatic compound; ii. at least one amine-containing compound; and iii. at least one electron-donating compound;
b) incubating the mixture to form at least one charge transfer complex; and
c) detecting the at least one charge transfer complex using that at least one non-laser-based light source.
[010] Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
a) preparing a mixture comprising the sample and at least one aromatic compound comprising at least one phosphate group;
b) incubating the mixture to form at least one Raman-active product; i) optionally adding an oxidizing agent; and ii) optionally adding a base;
c) detecting the at least one Raman-active product using at least one non-laser-based light source.
[01 1] Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
a) preparing a mixture comprising the sample, 5-aminosalicyclic acid, and a hydrogen peroxide chosen from an aromatic hydrogen peroxide, urea hydrogen peroxide, and hydrogen peroxide H2O2;
b) incubating the mixture to form at least one Raman-active product; and
c) detecting the at least one Raman-active product using at least one non-laser-based light source.
[012] Another embodiment is a method for detecting the activity of at least one enzyme in a sample comprising:
a) preparing a mixture comprising the sample, an aromatic amine comprising o-phenylenediamine, p-phenylenediamine, or m- phenylenediamine, and a hydrogen peroxide chosen from an aromatic hydrogen peroxide, urea hydrogen peroxide and H2O2;
b) incubating the mixture to form at least one Raman-active product; and
c) detecting the at least one Raman-active product using at least one non-laser-based light source. [013] Another embodiment is a method for detecting at least one target in a sample comprising:
a) preparing a mixture comprising the target;
b) incubating the mixture with at least one ligand specific for the target, wherein the at least one ligand comprises an enzyme; c) providing to the mixture:
i. optionally, at least one amine-containing compound;
ii. at least one aromatic compound; and
iii. at least one electron-donating compound;
d) incubating the mixture to form at least one Raman-active product; and
e) detecting the at least one Raman-active product using at least one non-laser-based light source.
[014] Another embodiment is a method for detecting at least one target in a sample comprising:
a) preparing a mixture comprising the at least one target;
b) incubating the mixture with at least one ligand specific for the at least one target, wherein the at least one ligand comprises a phosphatase;
c) providing to the mixture at least one aromatic compound comprising a phosphate;
d) incubating the mixture to form at least one Raman-active product;
i) optionally adding an oxidizing agent; and ii) optionally adding a base; and
e) detecting the at least one Raman-active product using at least one non-laser-based light source.
[015] Another embodiment is a kit for detecting at least one enzyme activity comprising:
a) (optionally) at least one aromatic compound;
b) at least one amine-containing compound;
c) at least one electron-donating compound; and
d) (optionally) suitable buffers for the at least one enzyme. [016] Another embodiment is a kit for detecting at least one enzyme activity comprising:
a) at least one aromatic compound comprising a phosphate;
b) optionally an oxidizing agent;
c) optionally a base; and
d) optionally suitable buffers for the at least one enzyme.
[017] In another embodiment, the Raman-active product is detected using resonance Raman spectroscopy. In another embodiment, the Raman-active product is detected using scattered light.
[0 8] In another embodiment, the at least one non-laser-based light source is a spectrophotometer capable of detecting Raman scattering using a fluorescence detection channel.
[019] In another embodiment, the at least one amine-containing compound comprises:
[020] wherein X is H, NH2, CI, Br, nitro, or benzyl, Y is H, CI, Br, or nitro, and Z is H, benzyl, or NH2. In one embodiment, X is NH2, and Y and Z are H. In another embodiment, X is CI, and Y and Z are H. In another embodiment, X is Br, and Y and Z are H. In another embodiment, X is nitro, and Y and Z are H. In another embodiment, X and Z are H and Y is CI. In another embodiment, X and Z are H and Y is Br. In another embodiment, X and Z are H and Y is nitro. In another embodiment, X and Z are benzyl and Y is H. In another embodiment, X and Z are NH2 and Y is H. [021] In another embodiment, the at least one amine-containing compound comprises:
[022] wherein X is H, OH, CI, Br, or nitro.
[023] In another embodiment, the at least one amine-containing compound comprises:
[024] wherein X is H, CI, Br, or nitro.
[025] In another embodiment, the at least one aromatic compound comprises:
[026] wherein W, X, Y, and Z are H or OH. In one embodiment, Y is OH and X, Y and Z are H. In another embodiment, W is OH, and X, Y and Z are H. In another embodiment, W and X are OH, and Y and Z are H. In another embodiment, W and Y are OH, and X and Z are H. In another embodiment, W and Z are OH and X and Y are H.
[027] In another embodiment, the at least one aromatic compound comprises:
[028] wherein X, Y, and Z are H or OH. In one embodiment, X is OH and Y and Z are H. In another embodiment, X and Y are OH and Z is H. In another embodiment X and Z are OH and Y is H. In another embodiment, Z is OH and X and Y are H.
[029] In another embodiment, the at least one aromatic compound comprises:
[030] wherein X and Y are H or OH. In one embodiment X is OH and Y is H. In another embodiment, X is H and Y is OH. [031] In another embodiment, the at least one aromatic compound comprises:
[032] wherein X and Y are H or OH. In one embodiment, X is OH and Y is H. In another embodiment, X is H and Y is OH.
[033] In another embodiment, the at least one amine-containing compound comprises an aromatic amine. In another embodiment, the aromatic amine comprises ortho-phenylenediamine, meta-phenylenediamine, or para- phenyleneamine:
In one embodiment, the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH;
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH; and
Z is H, OH, CI, Br, NH2, S03H, P04, or COOH. [035] In another embodiment, the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH;
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH; and
Z is H, OH, CI, Br, NH2, S03H, P04, or COOH.
[036] In another embodiment, the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH; and
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH.
[037] In another embodiment, the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH; and
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH.
[038] In another embodiment, the at least one aromatic compound comprises:
z
wherein each of X, Y, Z, and W are each independently H or OH.
[039] In one embodiment, the at least one amine-containing compound is chosen from 4-aminoantipyrene, 5-aminosalicyclic acid, and o-phenylenediamine; the at least one aromatic compound is chosen from 2-hydroxybenzyl alcohol, 4- chloro-3,5-dimethylphenol, 2-naphthol, 4-hydroxy-4-biphenyl-carboxylic acid, 5,7- dichloro-8-hydroxyquinoline, 4-chloro-1-naphthol, phenol, 4-amino-1 -phenyl-1- phosphate, 4-hydroxy-1-naphthyl-1-phosphate, 4-amino-1-naphthyl-1-phosphate, hydroquinone diphosphate, and 4,5 dihydroxy-naphthelene-2,7-disulfonic acid; and the at least one electron-donating compound is chosen from an organic hydrogen peroxide, urea hydrogen peroxide, and hydrogen peroxide (H202).
[040] In another embodiment, the at least one electron-donating compound is a hydrogen peroxide. In another embodiment, the hydrogen peroxide is chosen from an aromatic hydrogen peroxide, urea hydrogen peroxide and hydrogen peroxide (H202).
[041] In another embodiment, the at least one enzyme is a peroxidase or a phosphatase. [042] In another embodiment, the phosphatase is alkaline phosphatase.
[043] In another embodiment, the alkaline phosphatase is conjugated to an antibody, an avidin moiety, a streptavidin moiety, a biotin moiety, or a biotin-binding protein.
[044] In another embodiment, the at least one aromatic compound is 2- hydroxybenzyl alcohol, the at least one amine containing compound is 5- aminosalicyclic acid, the at least one electron-donating compound is urea hydrogen peroxide, and the at least one enzyme is a peroxidase.
[045] In another embodiment, the mixture is incubated in the presence of a base. In another embodiment, the base is sodium hydroxide.
[046] In another embodiment, the oxidizing agent is sodium metaperiodate.
[047] In one embodiment, the mixture further comprises biotin.
[048] In another embodiment, the ligand is chosen from a receptor and an antibody. In another embodiment, the ligand is an antibody.
[049] In another embodiment, the at least one target is an organism. In another embodiment, the organism is chosen from a bacteriophage, a bacterium, including E. coli, Listeria, Salmonella, Vibrio, Camphelbacter, and Staphylococcus, and a virus such as HIV, Hepatitis, Adenovirus, Rhino virus, and Human papilloma virus.
[050] In another embodiment the target is a component of an organism. In one embodiment, the component is a protein. In another embodiment, the protein is an interleukin. In one embodiment, the interleukin is IL-2. In another embodiment, the protein is chosen from C-Reactive protein, Tumor Necrosis Factor Receptor II, and Human Cardiac Troponin I. In another embodiment, the target is a component of an organism chosen from amino acids, nucleic acids, nucleotides, metabolites, carbohydrates, hormones, and metabolic intermediates.
BRIEF DESCRIPTION OF THE DRAWINGS
[051] The patent or application file contains at least one drawing executed in color. Copies of the patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
[052] Figure 1 is a flow chart of a typical prior art immunoassay technique (ELISA) for the detection of biological organisms or components.
[053] Figure 2 is a diagram of an embodiment of the disclosed apparatus. [054] Figure 3 is a flow chart of an embodiment of the disclosed technique for the detection of biological organisms and/or components.
[055] Figure 4 is a block diagram of the enzyme system for converting chemical components to a Raman-active compound.
[056] Figure 5 is a flow chart of a technique for choosing light frequencies to excite specific target molecules.
[057] Figure 6 is an illustration of a micro-fluidic channel designed to detect Raman-active compounds.
[058] Figure 7 is an illustration of an array of micro-fluidic channels such as might be incorporated into a custom integrated circuit.
[059] Figure 8 plots Raman spectra from an enzyme-linked immunoassay for a pathogenic bacteria, Listeria, utilizing an antibody linked to peroxidase and with shift numbers (cm"1) plotted on the abscissa and signal magnitudes plotted on the ordinate (arbitrary units) for a sample containing Listeria (a) and a sample not containing Listeria (b).
[060] Figure 9 A plots Raman spectra measured at 3260 cm'1 produced using Raman Reagent formulation A-1 in three experiments, while Figure 9 B plots SQR Raman spectra measured at 3500-4000 cm"1 produced using Raman Reagent A-1 in the three experiments.
[061] Figure 10 plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent A-1 (diamonds), and Raman Reagent A-2 (triangles) and A-3 (squares).
[062] Figure 1 1 plots SQR Raman spectra measured at 3500-4000 cm"1 produced using Raman Reagent formulation A-1 (diamonds), and Raman Reagent A-2 (squares and triangles).
[063] Figure 12 plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent formulation A-2 (squares) and A-2 with fresh HPRO in BSA diluent (diamonds).
[064] Figure 13 plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent B-1 (diamonds), B-2 (squares), B-3 (triangles), and B-4 ("Xs").
[065] Figure 4 plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent B-2 (squares) and B-2 with fresh HPRO in BSA diluent (diamonds). [066] Figure 15 A plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent C-1 while Figure 15 B plots the corresponding SQR Raman spectra measured at 3500-4000 cm"1.
[067] Figure 16 A plots Raman spectra measured at 3260 cm"1 produced using Raman Reagent D-1 while Figure 16 B plots the corresponding SQR Raman spectra measured at 3500-4000 cm"1.
[068] Figure 17 plots SQR Raman spectra measured at 3500-4000 cm'1 produced using Biotin-ASA-UP and ASA-UP.
[069] Figure 18 is a bar graph showing the relative sensitivity of the reagents tested.
[070] Figure 19 is a plot of the SQR Raman spectra measured at 3500- 4000 cm"1 and absorbance spectrum measured at 450 nm in IL-2 immunoassays using BASH-UP and TMB.
[071] Figure 20 A is a plot of an absorbance spectrum for a BASH-UP reaction, while Figure 20 B is an absorbance spectrum for an OPD reaction.
[072] Figures 21 A and 21 B are plots of fluorescence spectra of BASH-UP and OPD reactions without peroxidase, and Figures 21 C and 21 D are plots of fluorescence spectra of BASH-UP reactions with peroxidase.
[073] Figures 22 A and 22 B are plots of fluorescence spectra of OPD reactions without peroxidase, and Figures 22 C and 22 D are plots of fluorescence spectra of OPD reactions with peroxidase.
[074] Figures 23 A and 23 B are plots of Raman signals produced by BASH-UP and OPD reactions, respectively.
[075] Figure 24 A is a plot of Raman signals over time for an OPD reaction without peroxidase, and Figures 24 B-E are plots of Raman signals over time for OPD reactions with decreasing amounts of peroxidase.
[076] Figures 25 A-D are plots of SQR spectra over time for OPD reactions.
[077] Figure 26 A is a plot of Raman signal of benzoquinone and Figure 26 B is a plot of Raman signal of pyrogallol, both figures showing enhanced Raman signal upon adding sodium hydroxide. Figure 26 A (a) is a plot of Raman signal for benzoquinone with NaOH added, and Figure 26 A (b) is a plot of Raman signal for benzoquinone with no NaOH. Figure 26 B (a) is a plot of Raman signal for pyrogallol with NaOH added, and Figure 26 B (b) is a plot of pyrogallol with no NaOH. [078] Figure 27 A is a plot of Raman signal of 1 ,4-naphthaquinone, while Figure 27 B is a plot of Raman signal of 1 ,4-iminonaphthaquinone, both figures illustrating a dependence on periodate and sodium hydroxide. Figure 27 A (a) is a plot of Raman signal of 1 ,4-naphthaquinone with no periodate or NaOH. Figure 27 A
(b) is a plot of Raman signal of 1 ,4-naphthaquinone with periodate but no NaOH. Figure 27 A (c) is a plot of Raman signal of 1 ,4-naphthaquinone with no periodate but with NaOH. Figure 27 A (d) is a plot of Raman signal of 1 ,4-naphthaquinone with periodate and NaOH. Figure 27 B (a) is a plot of Raman signal of 1 ,4- iminonaphthaquinone with NaOH. Figure 27 B (b) is a plot of Raman signal of ,4- iminonaphthaquinone in borate buffer. Figure 27 B (c) is a plot of Raman signal of 1 ,4-iminonaphthaquinone with periodate and NaOH. Figure 27 B (d) is a plot of Raman signal of 1 ,4-iminonaphthaquinone with periodate but no NaOH.
[079] Figure 28 A is a logarithmic plot of Raman spectral values at 3300 cm" recorded for 4-aminophenylphosphate as a function of alkaline phosphatase- antibody conjugate concentration with the addition of oxidizing agent, while Figure 28 B shows the linear plot.
[080] Figure 29 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase conjugate concentration ranging from 0-1000 ng/mL with the addition of oxidizing agent, while Figure 29 B shows the range 0-10 ng/mL. Figure 29 A (a-f) show Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline phosphatase conjugate: (a) 1000 ng/ml, (b) 100 ng/ml,
(c) 10 ng/ml, (d) 1 ng/ml (e) 0.1 ng/ml; and (f) 0 ng/ml. Figure 29 B (a-e) shows Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline phosphatase conjugate: (a) 10 ng/ml, (b) 1 ng/ml, (c) 0 .1 ng/ml, (d) 0.01 ng/ml; and (e) 0 ng/ml.
[081] Figure 30 A is a logarithmic plot of Raman spectral values at 3300 cm"1 recorded for 4-aminophenylphosphate as a function of alkaline phosphatase concentration, while Figure 30 B shows the linear plot.
[082] Figure 31 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase concentration ranging from 0-2500 mU/mL, while Figure 31 B shows the range 0-25 mU/mL. Figure 31 A (a-f) shows Raman spectra of 4-aminophenylphosphate as a function of the concentration of alkaline
phosphatase: (a) 2500 mU/mL; (b) 250 mU/mL; (c) 25 mU/mL; (d) 2.5 mU/mL; (e) 0.25 mU/mL; and (f) 0 mU/mL. Figure 31 B (a-e) shows Raman spectra of 4- aminophenylphosphate as a function of alkaline phosphatase concentration: (a) 25 mU/mL; (b) 2.5 mU/mL; (c) 0.25 mU/mL; (d) 0.025 mU/mL; and (e) 0 mU/mL.
[083] Figure 32 shows Raman spectra of peroxidase detected using a fluorescent microplate reader.
[084] Figure 33 shows Raman spectra of peroxidase detected using a fluorescent microplate reader.
[085] Figure 34 shows the Raman spectral response of peroxidase at different emission wavelengths detected using a fluorescent microplate reader.
[086] Figure 35 shows dose response curves of peroxidase detected using a single lens Raman optics based reader (Raman SV) and a fluorescent microplate reader at 680 nm.
[087] Figure 36 shows dose response curves of peroxidase detected using a single lens Raman optics based reader (Raman SQR) and a fluorescent microplage reader at 680 nm.
[088] Figure 37 shows dose response curves of TNF-a detected using a single lens Raman optics based reader (Raman SV) and a fluorescent microplate reader at 680 nm.
[089] Figure 38 shows dose response curves of TNF-a detected using a single lens Raman optics based reader (Raman SQR) reader and a fluorescent microplate reader at 690 nm.
[090] Figure 39 shows dose response curves of TNF-a detected using a TMB colometric assay and a fluorescent microplate reader at 690 nm.
[091] Figure 40 shows the response of alkaline phosphatase on Tecan Infinite® M1000 multimode reader at different wavelengths.
[092] Figure 41 shows the results of the scan with alkaline phosphatase.
[093] Figure 42 shows the results from alkaline phosphatase from calf intestine for 45 minute reading at excitation wavelength 550 nm and emission at 580.
[094] Figure 43 shows the results from alkaline phosphatase from E. coli for 45 minute reading at excitation wavelength 550 nm and emission at 580 nm.
DETAILED DESCRIPTION OF THE INVENTION
[095] Areas such as food safety, medical diagnostics, veterinary
diagnostics, pathogen detection, forensics, and homeland security require the rapid and specific identification of biological organisms, such as contaminating bacteria, and biological components such as proteins, DNA, or other genetic material. Of particular need in the art are rapid and sensitive methods for detecting bacteria.
[096] A common assay to identify a bacterium in a sample is an
immunoassay, which relies on detecting an antibody bound to the bacterium.
Typically, the antibody is labeled and the presence of the antibody is detected by assaying for the presence of the label. Alternatively the antibody is conjugated to an enzyme, and the presence of the antibody-enzyme conjugate is detected by assaying for enzymatic activity. A commonly used assay that employs an enzyme- antibody conjugate is the enzyme linked immunosorbant assay (ELISA). In standard assays, enzymatic activity can be measured by incubating the enzyme-antibody conjugate in the presence of reactants that are converted by the enzyme into products which can be detected through colorimetric, fluorogenic, and
chemiluminescent means.
[097] However, detection by colorimetric, fluorogenic, and
chemiluminescent means suffers from several deficiencies such as limited dynamic range, limited sensitivity, and interference from background.
[098] While Raman spectroscopy has several advantages over these methods, it generally cannot be used in combination with commonly used colorimetric, fluorogenic, and chemiluminscent reagents because they typically do not produce useful Raman spectra. For example, the colorimetric reagents 3,3', 5,5'- tetramethelene benzidine (TMB), and azinobisethlybenzthiazolinesulfonic acid (ABTS) do not produce Raman spectra useful for detecting organisms. Accordingly, reagents that produce Raman-active products useful for detecting organisms are desired, including reagents that can be used in immunoassay formats employing enzyme-antibody conjugates.
[099] Reagents useful for detecting a bacterium in an immunoassay format using Raman scattering have certain desired characteristics. First, the reagents should produce a Raman signal in an area of the Raman spectrum that does not already have background signal produced by the bacterium. Second, the Raman signal produced by the reagents should be quantifiable, allowing for detection over a wide range of concentrations.
[0100] Certain embodiments of the present disclosure are based in part on the discovery that certain amine-containing compounds can be used in
immunoassay formats to detect organisms and components, such as nucleic acids and proteins. These reagents are enzymatically converted to produce iminoquinone or other products that have Raman signals at spectral regions not already containing Raman signals from the bacterium. Detection of the Raman signals indicates the presence of the enzyme. When the enzyme is part of an antibody-conjugate used in an ELISA assay, detection of Raman signals indicates the presence of the target of the ELISA. Alternatively, Raman-active reagents can be incubated with enzymes that convert these reagents into products with Raman spectra that differ from the reagents. The change in the Raman signal indicates the presence of the enzyme. Accordingly, use of these reagents allows for the rapid, specific and quantitative detection of enzymatic activity.
[0101] Certain embodiments of the present disclosure are also based in part on the discovery that certain combinations and amounts of the reagents of the disclosure produce superior sensitivity. This sensitivity can be further enhanced through use of the Single Quantifiable Result (SQR) method of the disclosure, which employs multiple wavenumber spectroscopic analyses.
[0102] Additional embodiments of the present disclosure are based in part on the discovery that the Raman-active products may be detected using a non-laser- based light source, such as a fluorescence-detection device, a laser-based light source, or both.
[0103] Certain embodiments of the present disclosure are also based in part on the discovery that the colorimetric reagent o-phenylenediamine (OPD) can be used to produce Raman-active products, in contrast to other colorimetric reagents. OPD can be used in combination with Raman scattering to measure real-time kinetics of enzyme activity.
[0104] Additional embodiments of the present disclosure are based in part on the discovery that compounds having at least one phosphate group can be used as phosphatase substrates to produce Raman-active products, or precursors to Raman- active products. The phosphatase substrates may be aromatic compounds that may be enzymatically dephosphorylated in the presence of a phosphatase to form the corresponding phenols or aminophenols. The phenols and aminophenols may then autooxidize or become oxidized by the addition of an oxidizing agent to generate the corresponding Raman-active quinones or iminoquinones. The phosphatase substrates may be used in an immunoassay format. The phosphatase may be alkaline phosphatase. The precursors to Raman-active products may be converted to Raman-active products by exposure to a base. The base may be NaOH.
[0105] While not being bound by any theory, it is believed that the embodiments of the present disclosure are based on the ability of certain
compounds to form charge-transfer complexes that can be detected by Raman scattering. The presence of such complexes is supported by the discovery that these compounds produce broad Raman peaks consistent with formation of charge transfer complexes. See, e.g., Rathore et al. , "Direct Observation and Structural Characterization of the Encounter Complex in Bimolecular Electron Transfers with Photoactivated Acceptors," J. Am. Chem. Soc. 1 19: 1 1468-1 1480 (1997). The discovery that certain compounds produce Raman-detectable charge transfer complexes provides a means to select reactants that will produce such complexes.
Definitions
[0106] "Antibody", as used herein, means an immunoglobulin or a part thereof, and encompasses any polypeptide comprising an antigen-binding site regardless of the source, method of production, and other characteristics. The term includes for example, polyclonal, monoclonal, monospecific, polyspecific, humanized, single-chain, chimeric, synthetic, recombinant, hybrid, mutated, and CDR-grafted antibodies. A part of an antibody can include any fragment which can still bind antigen, for example, an Fab, F(ab')2, Fv, scFv. The origin of the antibody is defined by the genomic sequence irrespective of the method of production.
[0107] The terms "polypeptide," "peptide," and "protein," are used
interchangeably to refer to a polymeric form of amino acids of any length, which can include naturally-occurring amino acids, coded and non-coded amino acids, chemically or biochemically modified, derivatized, or designer amino acids, amino acid analogs, peptidomimetics, and depsipeptides, and polypeptides having modified, cyclic, bicyclic, depsicyclic, or depsibicyclic peptide backbones. The term includes single chain protein as well as multimers.
[0108] The term "amino acid" refers to monomeric forms of amino acids, which can include naturally-occurring amino acids, coded and non-coded amino acids, chemically or biochemically modified, derivatized, or designer amino acids, amino acid analogs, peptidomimetics, and depsipeptides. [0109] The terms "polynucleotide," "nucleic acid," "nucleic acid sequence," "polynucleotide sequence," and "nucleotide sequence" are used interchangeably herein to refer to polymeric forms of nucleotides of any length. The polynucleotides can comprise deoxyribonucleotides, ribonucleotides, and/or their analogs or derivatives.
[01 10] The term "nucleotide," refers to monomeric nucleotides and includes deoxyribonucleotides, ribonucleotides, and/or their analogs or derivatives.
[01 11] The term "ligand" refers to a molecule that binds to another molecule, including a receptor.
[0112] The term "light source" refers to any source of energy that falls within the electromagnetic spectrum. Light sources include, but are not limited to, light bulbs, lasers, diodes, masers, and gas-discharge lamps including neon lamps, xenon lamps, xenon flash lamps, and mercury-vapor lamps.
Immunoassay Formats
[01 13] The present disclosure can be practiced in various formats. In one embodiment, the format is an immunoassay. In certain immunoassay embodiments, a target biologic is first bound to an antibody that is attached to a solid surface.
Unbound components of the test sample are then optionally washed away leaving only the bound biologic/antibody combinations, which can be detected by Raman light scattering.
[01 14] In other immunoassay embodiments, a target biologic is first bound to an antibody, or an antibody-enzyme conjugate. This biologic/antibody or
biologic/antibody-enzyme combination reacts with a substrate compound, such as an aromatic organic compound having at least one phosphate group, via the antibody portion of the biologic/antibody or biologic/antibody-enzyme combination. The substrate compound then further oxidizes into a Raman-active product. In such embodiments, quantification of the target biologic is thus achieved by detection of the Raman-active product.
[01 15] In one embodiment, a combination of Raman spectroscopy and biological labeling techniques are used to identify and quantify biological
components, such as proteins or peptides including any post-translational modifications, in specific conformations or conditions associated with disease: for example, prion proteins. [01 16] To increase the sensitivity an additional step is envisioned where one or more new reactants are then introduced and become bound to the
biologic/antibody combination. The combination of the new reactant(s) with the biologic/antibody combination can now be detected using Raman scattering of light. Examples of such reactants include, but are not limited to the reagents listed in Table 1.
TABLE 1
Sensitivity Enhancing Reagents
1. antibodies labeled with Raman-active molecules
2. enzyme/antibody conjugates combined with additional chemical
reactants that react to form Raman-active molecules;
3. Raman-active reactants that chemically interact with the biologic; and
4. chemical reactants that are converted by the biologic into Raman- active molecules.
[01 17] It is also envisioned that instead of starting with a biologic/antibody combination, the Raman detection methods can use chemicals that interact with the biologic without the antibody.
[01 18] The Raman-based methods can be applied to many immunoassays including, but not limited to, the detection of Human IL-1 1 , Rat C- reactive Protein, Soluble Tumor Necrosis Factor Receptor II, and Human Cardiac Troponin I.
[01 19] The Raman-based methods can be applied to the detection of variety of organisms and components. In one embodiment, bacteriophage are detected. In another embodiment, bacteria, including E. coli, Listeria, Salmonella, Vibrio, Camphelbacter, and Staphylococcus and detected. In another embodiment, viruses such as HIV, Hepatitis, Adenovirus, Rhino virus, Human papilloma virus are detected. In another embodiment components, including proteins, amino acids, nucleic acids, nucleotides, metabolites, hormones, and metabolic intermediates are detected.
[0120] It is also envisioned that specific binding partners or ligands for the target biologic other than antibodies may be used, for example, a biological receptor protein. [0121] Although many of the techniques disclosed herein are associated with the detection of biological organisms and components, the disclosure is applicable to the detection of inorganic components, organic components, contaminants, or toxins in a sample. The disclosed detection techniques can be enhance by using reactants that exhibit resonance Raman light scattering. For certain reactants, there are frequencies of scattered light that are more intense which are specific to the structure of these reactants. The resonance phenomena in certain embodiments of the present disclosure is solely related to the chemical structure and interaction of the target molecule, and not to any solid surface interaction such as found in the technique known as Surface Enhanced Resonance Raman Scattering (SERRS).
Single Quantifiable Result (SQR)
[0122] Raman spectra can be analyzed by obtaining a Single Quantifiable Result (SQR). The SQR number is the difference between a Raman spectra corresponding to a targeted analyte measured in a sample, and any background Raman signal/spectra observed in the measurement process. The steps of the SQR process are shown in Table 2.
TABLE 2
SQR Procedure
1. Optionally, spectra for the background of the sample (Negative Control) and for the samples being investigated (Test Samples) are measured.
2. The Raman values for a range of wave numbers, such as every 2nd wave number, or for every wave number, for the Negative Control and Test Samples are measured.
3. The difference between the Raman value for the Test Sample and the
Negative Control is determined for each wave number measured and the sum of these values is calculated ("Sum of the Differences").
4. The difference between each Raman value for the Test Sample and the
Negative Control is squared and the sum of these values is calculated ("Sum of the Squares of the Differences").
5. The square root of the "Sum of the Squares of the Differences" is calculated ("Square Root of the Sum of the Squares of the Differences"). This value is designated as the SQR value.
[0123] The SQR process can include an assessment of whether the Raman signals from the sample and background are appropriate (i.e., "valid") and sufficient to indicate the presence of the targeted analyte in the sample (i.e., "positive value"). The SQR process may be performed manually or with designed computer software. The Raman signals for multiple wave numbers are tabulated for the background and test spectra. In one embodiment, every 2nd wave number is tabulated for both the background and test spectra. In another embodiment, every wave number is tabulated for both the background and test spectra. In one embodiment the range of wave numbers is from 2000 to 4000 cm "1. In another embodiment, the range of wave numbers is from 3500 to 4000 cm ~ The difference between the test signal and background signal is determined for a range of wave numbers and the square of this difference is stored. The sum of the squares is determined, and the square root of this sum is the SQR value.
[0124] When using SQR, its validity can be verified by ensuring that the negative and/or sample run is run appropriately (no systematic error resulting in an incorrect assay), so that the Raman spectra has the intended meaning. If a background measurement is used, the background sample must be representative of the background signal in the test samples, and not due to random signal such as signal obtained when Raman readings are taken without a sample tube in the instrument. Sample spectra must not consistently run below (less than) that of the negative control. Mathematically, the difference between a lower running sample and the background would be transformed into a positive value, and potentially interpreted as a "positive" SQR signal.
[0125] The following "Validity" analysis can be performed. The Raman value of the background sample ("Negative Control") at a wave number, for example, 3260 cm"1 should run as expected (above a minimum and below a maximum value). This determination will aid in ensuring that a correct sample was run as the negative control, and that the assay was run correctly. The SQR value of the positive control should not run below an expected value. This will aid in ensuring that a correct sample was run as the positive control, and that the assay was run correctly. The "Sum of the Differences" for each test sample should not run below an expected value. These analyses help to ensure that the sample spectrum is not consistently running below (less than) that of the negative control. The expected minimum and maximum values can be determined empirically by establishing minima and maxima from values obtained in repeated experiments.
[0126] The SQR method can be carried out manually or with the aid of a computer. One embodiment of the disclosure is a computer bearing machine operable language for the calculation of the SQR.
Instrumentation
[0127] The Raman-active compounds of the invention may be detected using an instrument with a traditional laser-based light source. Such instruments include, for example, a Raman Systems INC QE 65000 Raman Detector and a Lambda Solutions model PS-1 detector. In other embodiments of the invention, the Raman- active compounds may be detected using an instrument with a non-laser-based light source. In some embodiments, the non-laser-baesd light source may comprise a high-intensity light source. In additional embodiments, the high-intensity light source may comprise a xenon lamp, a xenon flash lamp, a neon lamp, or a mercury-vapor lamp. Suitable instruments comprising a non-laser-based light source include, for example, fluorescence detectors such as, for example, Tecan Infinite 200, Tecan Infinite® 200 PRO, and Tecan Infinite® M1000.
[0128] It is also envisioned that embodiments of the present disclosure can be implemented on a micro-fluidic channel (or well) integrated circuit using micro or nano-fabrication technology in which the binding partner is immobilized in one or more micro-fluidic channels in a custom integrated circuitry which would also include equipment to detect the Raman spectra generated by the methods of the invention. Such an implementation could detect single biological components such as pathological bacteria, proteins or genetic material.
[0129] Thus an object of certain embodiments of the present disclosure is to have a system for the detection of target biological organisms or components that utilizes a combination of chemical interactions including binding with a final step of Raman light scattering.
[0130] Another object of certain embodiments of the present disclosure is to have a system for the detection of target inorganic or organic components that utilizes a combination of chemical interactions including binding with a final step of Raman light scattering.
[0131] Another object of certain embodiments of the present disclosure is to combine an immunoassay with detection using Raman light scattering.
[0132] Still another object of certain embodiments of the present disclosure is to increase sensitivity of detection by the use of chemical reactants that produce resonance Raman light scattering.
[0133] Yet another object of certain embodiments of the present disclosure is to have an integrated circuit design with micro-fluidic channels or wells which can perform the combination of binding and Raman light scattering measurements.
[0134] These and other objects and advantages of the present disclosure will become obvious to a person of ordinary skill in this art upon reading of this disclosure including the associated drawings.
[0135] Figure 1 is a flow chart of a typical prior art immunoassay technique (ELISA) ( 0) for the detection of biological organisms or components. The process begins by step (11) of preparing the liquid sample that includes the target biologic. For example, the sample can be prepared by pre-enrichment in a growth medium such as half-Frasier's broth or other suitable microbial growth medium. Alternately, a liquid sample for testing may be obtained from any liquid source. Solid material may be immersed in an appropriate liquid solution and potential target organism or molecules placed in solution and then sampled in the liquid. In the next step (12) the prepared liquid sample is combined (or mixed) with a binding partner that has been attached to a solid surface. Typical binding partners include antibodies,
bacteriophage, and bacteriophage proteins. For example plastic microtiter plates, latex beads or magnetic microparticles may be used. Other solid supports such as nitrocellulose, filter paper, nylon and other plastics may also be used. The antibody/biologic combination is then incubated in step (13) to allow time for the biologic and antibody to bind together. Once this has occurred the combined binding partner/biologic is decanted (poured off) and washed to remove unbound biologies and other unwanted materials. New reactants are added in step (15) to enhance the sensitivity of the mixture to detection of signal molecules by various methods.
Examples of such reactants include those listed in Table 3.
TABLE 3
Sensitivity Enhancing Reagents
1. binding partners labeled with radioactive molecules
2. binding partners labeled with fluorescent molecules
3. enzyme/binding partner conjugates combined with additional chemical
reactants that react to form light absorbing molecules
4. enzyme/binding partner conjugates combined with additional chemical
reactants that react to form light producing molecules
5. enzyme/binding partner conjugates combined with additional chemical
reactants that react to form light reflecting molecules
[0136] The mixture containing the bound binding partner/biologic and new reactants is the incubated in step (13) to allow time for the reaction to occur. At this point in many cases, the reaction part of the process (10) is complete and step (16) of measuring the molecules produced or included in steps (11 ) through (15) inclusive can be performed. If additional reactants are required, steps (14), (15) and (13) may be repeated one or more times in succession until the appropriate signal molecules are present.
[0137] The measurement of the signal molecule(s) provides a quantitative result that can then be analyzed and compared in step (17) to a known set of calibrated responses of known concentrations of the target biologic. This comparison results in step (18) which is the quantified result and associated report of the concentration of the target biologic in the sample prepared in step (1 1).
[0138] Although the descriptions of the process (10) of FIG. 1 have been associated with the detection of a biological organism or component, the process (10) is also applicable to the detection of many types of molecules to which antibodies or other binding partners can react.
[0139] Figure 2 is a diagram of an embodiment of a laser-based Raman detection sub-system (20). A laser (21) produces a laser beam (22) which is focused by the focusing optics (23) into a focused laser beam (24) which hits the target sample (25). The backscattered light (26) from the sample (25) is focused into the beam (28) by the focusing optics (27). The beam (28) is directed into the
spectrometer (30) with detector (31). The output from the detector (31) is the signal (32) which is received by the personal computer (40) for analysis, storage and/or printing with the printer (42). The laser (21 ) is typically a continuous wavelength (CW) laser with output in the visible range. For example, an argon ion laser, helium neon laser, argon ion laser pumped tunable dye laser, or a diode laser in the green, red or other frequency. Focusing optics (23) and (27) include mirrors, lenses, irises, shutters, diffraction gratings, and/or polarizers. The target sample (25) may be liquid, gas or solid and in certain embodiments, the target sample would use a liquid or precipitated solid. The spectrometer (30) spatially separates the scattered light based on wavelength. An example of a usable spectrometer for the present disclosure is the Lambda Solutions model PS-1. The detector (31) measures the amplitude of the light spatially separated by the spectrometer (30) and converts this into an electrical signal (analog or digital). In certain embodiments, the detector would provide the electrical signal using a standardized computer interface such as RS-232, USB, parallel, IEEE 1394. An example of a usable detector (30) for the present disclosure is a Raman Systems INC QE 65000 Raman Detector or a Lambda Solutions model PS-1 detector. The personal computer (40) can be any desktop or laptop PC with an appropriate interface to the detector (31) and software designed to analyze, store and/or print the spectrum of the backscattered light (26) received by the spectrometer (30).
[0140] Figure 3 is a flow chart of an embodiment of the present disclosure (30) for the detection of biological organisms and/or components. The process begins by step (31 ) of preparing the liquid sample that includes the target biologic. For example, the sample may be prepared by pre-enrichment in a growth medium such as half-Frasier's broth or other suitable microbial growth medium. Alternately, a liquid sample for testing may be obtained from any liquid source. Solid material may be immersed in an appropriate liquid solution and potential target organism or molecules placed in solution and then sampled in the liquid. In the next step (32), the prepared liquid sample is combined (or mixed) with an antibody that has been attached to a solid surface. For example, plastic microtiter plates, latex beads or magnetic microparticles may be used. The antibody/biologic combination is then incubated in step (33) to allow time for the biologic and antibody to bind together. Once this has occurred the combined antibody/biologic is decanted (poured off) and washed to remove unbound biologies and other unwanted materials. New reactants are added in step (35) to enhance the sensitivity of the mixture for detection of the Raman light scattering. Examples of such reactants are listed in Table 1.
[0141] The mixture containing the bound antibody/biologic and new reactants is the incubated in step (33) to allow time for the reaction to occur. At this point in many cases, the reaction part of the process (30) is complete and step (36) of measuring Raman light scattering from Raman-active molecules produced by steps (31 ) through (35) inclusive can be performed. If additional reactants are required, steps (34), (35) and (33) may be repeated one or more times in succession until the appropriate Raman-active molecules are present.
[0142] The measurement of Raman light scattering can then be analyzed and compared in step (37) to a known set of calibrated responses of known concentrations of the target biologic. This comparison results in step (38) which is the quantified result and associated report of the concentration of the target biologic in the sample prepared in step (31 ).
[0143] Listeria may be measured in an (enzyme-linked immunosorbant assay) ELISA format. 100 microliters of various concentrations of bacteria; 100,000, 50,000, 25,000, 12,500, 6,250 and 0 colony forming units (cfu) per ml are added to microwells coated with anti-Listeria antibodies. After an incubation period between 30 and 60 minutes at 37°C, the wells are decanted and washed with a mild detergent solution three times. 100 μΙ of peroxidase-conjugated anti- Listeria antibodies are added to the well and incubated for 1 to 4 hours at 37°C. The wells are decanted and washed with a mild detergent solution three times. A mixture of 4-hydroxyl benzyl alcohol (80.6 mM), 4-aminoantipyrene (24 mM), Urea-Hydrogen Peroxide (10.6 mM) in 125 mM MES buffer (pH 6.0) is added and color is allowed to develop for 30-60 minutes. Raman Spectra of developed color from each well are developed and responses quantified.
[0144] Although the descriptions of the process (30) of FIG. 3 have been associated with the detection of a biological organism or component, the process (30) is also applicable to the detection of inorganic or organic molecules,
contaminants or toxins.
[0145] Figure 4 is a block diagram for a chemical conversion system (40) which uses an enzyme for converting chemical components to a Raman-active compound. For example, one or more reactants designated (41), (42) and (43) are mixed with a biological catalyst (44). The biological catalyst (44) may be an enzyme specific for metabolizing the reactants provided or RNA structures designed to interact with the one or more reactants (41 ), (42), and (43). A conversion or combination of the reactants occurs in the reaction (45) and a measurable product (46) is formed. For example, the reactants and those in Table 4 are mixed together in the presence of peroxidase (44) and urea hydrogen peroxide (UP) (43).
Reactants useful in peroxidase assays
TABLE 4
Reactants Producing Raman-active Products
2-hydroxybenzyl alcohol (HBA) (41)
5-aminosalicyclic acid (ASA) (42)
4- chloro-3,5-dimethylphenol (CDMP) (41)
5- aminosalicyclic acid (ASA) (42)
2-naphthol (NAP) (41)
5-aminosalicyclic acid (ASA) (42)
4- hydroxy-4-biphenyl-carboxylic acid (HBCA) (41)
5- aminosalicyclic acid (ASA) (42)
5,7-dichloro-8-hydroxyquinoline (DHQ) (41)
5-aminosalicyclic acid (ASA) (42)
4-chloro-1-naphthol (41)
4-aminoantipyrene (42)
phenol (41)
4-aminoantipyrene (42)
[0146] When mixed together, these reactants will yield an iminoquinone compound which is detectable using Raman spectroscopy. A reaction using HBA, ASA and UP is referred to as BASH-UP.
[0147] Additional reactants that may produce Raman-active products can be used in the disclosed methods, such as compounds comprising a least one hydroxyl group and one amino group at positions 1 and 4 in a benzene or naphthalene.
Inclusion of additional groups such as carboxyi, amine, chlorine, bromine, nitro and other functional groups may enhance the Raman scattering. Such compounds include:
[0148] wherein X is H, NH2, CI, Br, nitro, or benzyl, Y is H, CI, Br, or nitro, and Z is H, benzyl, or NH2. In one embodiment, X is NH2, ancTY and Z are H. In another embodiment, X is CI, and Y and Z are H. In another embodiment, X is Br, and Y and Z are H. In another embodiment, X is nitro, and Y and Z are H. In another embodiment, X and Z are H and Y is CI. In another embodiment, X and Z are H and Y is Br. In another embodiment, X and Z are H and Y is nitro. In another embodiment, X and Z are benzyl and Y is H. In another embodiment, X and Z are NH2 and Y is H.
[0149] Such compounds also include:
[0150] wherein X is H, OH, CI, Br, or nitro (N02).
[0151] Such compounds also include:
[0152] wherein X is H, CI, Br, or N02.
[0153] Additional compounds that may produce Raman-active products in the disclosed methods include compounds comprising at least two hydroxyl functions in 1 , 2 or 1 , 4 positions in a benzene or naphthalene ring.
[0154] Such compounds include:
[0155] wherein W, X, Y, and Z are H or OH. In one embodiment, Y is OH and X, Y and Z are H. In another embodiment, W is OH, and X, Y and Z are H. In another embodiment, W and X are OH, and Y and Z are H. In another embodiment, W and Y are OH, and X and Z are H. In another embodiment, W and Z are OH and X and Y are H.
[0156] Such compounds include polyphenols, such as:
[0157] wherein X, Y and Z are H or OH. In one embodiment, X is OH and Y and Z are H. In another embodiment, X and Y are OH and Z is H. In another embodiment X and Z are OH and Y is H. In another embodiment, Z is OH and X and Y are H.
[0158] Additional compounds that may produce Raman-active products in the disclosed methods include compounds comprising hydroxymethlene (-CH2OH) group in a benzene or naphthalene. Inclusion of additional hydroxyl groups at positions 1 , 4, and 6 may enhance the Raman scattering.
[0159] Such compounds include:
[0160] wherein X and Y are H or OH. In one embodiment X is OH and Y is H. In another embodiment, X is H and Y is OH.
[0161] Such compounds also include:
[0162] wherein X and Y are H or OH. In one embodiment, X is OH and Y is H. In another embodiment, X is H and Y is OH.
[0163] Such compounds also include aromatic amines, including compounds comprising ortho-phenylenediamine, meta-phenylenediamine, and para- phenyleneamine:
[0164] Such compounds also include 2,4-diaminobenzyl alcohol, 2-amino- 1-naphthol, and 4-aminoantipyrene.
[0165] The product of the reaction (45) may be used as a quantitative or qualitative reporting molecule for the reaction and as such may be used as a probe for the presence of specific biological targets if conjoined with, for example, specific antibodies or biological or chemical binding partners.
Reactants comprising phosphate groups
[0166] Certain compounds may spontaneously form Raman-active products upon exposure to air ("auto-oxidation"). Such compounds are ill-suited for use in certain assay formats, such as ELISA, because they exhibit Raman signals without being acted on by an enzyme. The present disclosure provides modified versions of these reactants that allow for their use in Raman scattering-based assays.
Specifically, hydroxyl groups present in compounds of the disclosure, which may spontaneously oxidize, can be modified with phosphate groups to prevent spontaneous oxidation. As such, these compounds further expand the types of compounds that can be used in the methods presently disclosed. In other embodiments, reactants comprising phosphate gropus may be oxidized by the addition of an oxidizing agent. The present disclosure also provides methods for using Raman scattering based on detecting phosphatase activity.
[0167] Additional reactants that produce Raman-active products can be used in the presently-disclosed methods, such as compounds comprising at least one phosphate group. Such compounds include aromatic organic compounds
comprising at least one phosphate group, for example compounds comprising benzene or naphthalene rings having at least one phosphate group as a substituent. Inclusion of additional substituent groups such as carboxyl, amine, chlorine, bromine, nitro and/or other functional groups may enhance the Raman scattering of the Raman-active product. Such compounds according to the present disclosure may, for example, have functional groups that are ortho (1 ,2) and/or para (1 ,4) to each other.
Hvdroxyphenyl phosphates
[0168] It is known that 4-hydroxyphenyl phosphate undergoes catalytic dephosphorylation to yield 4-hydroxyphenol (hydroquinone). This is then rapidly oxidized by air to form benzoquinone, which has been used in electrochemical immunoassays (Jenkins et al., Anal. Biochem., 168, 292, 1988).
[0169] Compounds that are hydroxylated in the ortho (1 , 2) and/or para (1 , 4) positions can undergo rapid oxidation in air to generate corresponding quinone compounds. Compounds such as, catechol (1 , 2-dihydroxybenzene), hydroquinone (1 , 4-dihydroxybenzene), and pyrogallol (1 , 2, 3- trihydroxybenzene) were observed to oxidize rapidly in air to form the corresponding quinones, which on treatment with a base (strong sodium hydroxide solution) generated high Raman scattering which can be quantitated. The NaOH-dependent signal was reversible (disappeared upon acidification of the reaction, reappeared upon the addition of NaOH).
[0170] In some embodiments of the present disclosure, the aromatic organic compounds comprising at least one phosphate group have the following structure:
wherein X is H, OH, CI, Br, N02, NH2, S03H, or COOH; Y is H, OH, CI, Br, N02, S03H or NH2; W is OH or P04 and Z is H, OH, CI, Br, S03H, P04 or NH2. In one embodiment, X, Y, and Z are H. In another embodiment, X is OH, and Y and Z are H. In another embodiment, X is N02, and Y and Z are H. In another embodiment, X is CI, and Y and Z are H. In another embodiment, X is Br, and Y and Z are H. In another embodiment, X is COOH, Y is OH, and Z is NH2. In another embodiment, X is CI, Y is OH, and Z is NH2. In another embodiment, X is S03H, Y is OH, and Z is NH2.
[0171] Without being bound by any particular theory, such compounds may undergo catalytic dephosphorylation by reaction with alkaline phosphatase (ALP), and then oxidize to form a Raman-active quinone compound. This is exemplified by the following reaction:
[0172] Such compounds oxidized in the ortho (1 ,2) or para (1 ,4) position, including, for example, catechol (1 , 2-dihydroxy-benzene), hydroquinone (1, 4- dihydroxybenzene), and pyrogallol (1 , 2, 3- trihydroxybenzene), may undergo rapid oxidation in air to generate the corresponding quinone.
[0173] In some embodiments of the present disclosure, the Raman scattering of the quinone product is enhanced upon treatment with a base such as strong sodium hydroxide (NaOH) solution. This signal enhancement may be pH- dependent (i.e., NaOH dependent) such that the Raman scattering decreases upon addition of an acid, and increases upon addition of a base (restoring Raman scattering enhancement). For example, auto-oxidation and Raman scattering enhancement upon addition of NaOH has been observed for catechol, pyrogallol, and 1 ,2,4-benezenetriol, which have the following structures:
catechol pyrogallol 1 ,2,4-benzenetriol
Aminophenyl phosphates
[0174] It is also known that 4-aminophenyl phosphate undergoes catalytic dephosphorylation to yield 4-aminophenol, which is rapidly oxidized by air to form 1 , 4-iminoquinone in alkaline conditions (Tang et al., Anal. Chim. Acta, 214, 197, 1988). This iminoquinone compound has been used in highly sensitive detection of alkaline phosphatase by electrochemical immunoassays (Thompson et al., Anal. Chim. Acta, 271 , 223, 1993).
[0175] It was observed that compounds such as 4-aminophenol, 4-amino-2- chlorophenol, and 2, 4-diaminophenol rapidly undergo oxidation in air to form the corresponding iminoquinone compound, which upon treatment with a base (strong sodium hydroxide solution) generate high Raman scattering that can be quantitated. The Raman scattering of the sodium hydroxide treated iminoquinones from 4- aminophenol, 4-amino-2-chlorophenol and 2, 4-diaminophenol is similar to the sodium hydroxide-treated benzoquinone described above.
[0176] In other embodiments of the present disclosure, the aromatic organic compounds comprising at least one phosphate group further comprise at least one amine group, and have the following structure:
wherein X is H, OH, CI, Br, N02, S03H, P04 or NH2; Y is H, OH, CI, Br, N02, S03H or NH2; and Z is H, OH, CI, Br, S03H, P04 or NH2. In one embodiment, X, Y, and Z are H. In another embodiment, X is OH, and Y and Z are H. In another
embodiment, X is N02, and Y and Z are H. In another embodiment, X is CI, and Y and Z are H. In another embodiment, X is Br, and Y and Z are H.
[0177] Without being bound by any particular theory, such compounds may undergo catalytic dephosphorylation by reaction with alkaline phosphatase (ALP), then oxidize to form the corresponding Raman-active iminoquinone compound. This is exemplified by the following reaction:
[0178] Upon treatment with a base (strong NaOH solution, for example), the iminoquinones may generate enhanced Raman scattering that may be quantitated.
Naphthyl phosphates
[0179] Another phosphate-containing compound, 4- hydroxynaphthylphosphate, is known to undergo catalytic dephosphorylation to yield 1 , 4-dihydroxynaphthalene. This is then rapidly oxidized by air to form 1 , 4- naphthaquinone, which has been used in an amperometric immunoassay with high detection sensitivity of detection (Masson et al., Anal. Chim. Acta, 402, 29-35, 1999). Naphthyl compounds substituted with functional groups in the 1 , 2, or both positions may undergo similar rapid oxidation in air to generate the corresponding quinones. For example, 1 , 4- dihydroxynaphthalene was observed to undergo rapid oxidation in air to form 1 , 4-naphthaquinone, whereas 1 , 3- dihydroxynaphthalene did not show auto-oxidation. Further, 1 , 4-naphthaquinone was found to generate a high Raman scattering with or without an oxidizing agent. The addition of a strong base such as NaOH was also found to change the scattering pattern.
[0180] In other embodiments of the present disclosure, the aromatic organic compounds comprising at least one phosphate group further comprise at least one hydroxyl group and have the following structure:
wherein X is H, OH, CI, Br, N02, S03H, P04 or NH2 and Y is H, OH, CI, Br, N02, S03H or NH2. In one embodiment, X and Y are H. In another embodiment, X is OH and Y is H. In another embodiment, X is N02 and Y is H. In another embodiment, X is CI and Y is H. In another embodiment, X is Br and Y is H.
[0181 ] Without being bound by any particular theory, such compounds may undergo catalytic dephosphorylation to yield the corresponding
dihydroxynaphthalene, which can further oxidize in air to form a Raman-active naphthaquinone. The reaction is exemplified below:
Aminonapthyl phosphates
[0182] Another phosphate-containing compound, 4- aminonaphthylphosphate, is known to undergo catalytic dephosphorylation to yield 4-amino-1 -naphthol. This is then rapidly oxidized by air to form 1 , 4- iminonaphthaquinone, which has been used in amperometric immunoassays with high sensitivity of detection (Masson et al., Talanta, 64, 174-180, 2004).
[0183] 1 , 4-iminonaphthaquinone was observed to generate a strong Raman scattering with or without an oxidizing agent and could be used to quantify a target biologic by Raman spectroscopy. The Raman scattering may change with the addition of a strong base such as NaOH.
[0184] In other embodiments of the present disclosure, the aromatic organic compounds comprising at least one phosphate group further comprise at least one amine group and have the following structure:
wherein X is H, OH, CI, Br, N02, S03H or P04; and NH2 and Y is H, OH, CI, Br, N02, S03H or NH2. In one embodiment, X and Y are H. In another embodiment, X is OH and Y is H. In another embodiment, X is N02 and Y is H. In another embodiment, X is CI and Y is H. In another embodiment, X is Br and Y is H.
[0185] Without being bound by any particular theory, such compounds may undergo catalytic dephosphorylation to yield the corresponding amino-naphthol, which can further oxidize to form a Raman-active iminonaphthaquinone. The reaction is exemplified below:
Additional phenylphosphates
[0186] In other embodiments of the present disclosure, the aromatic organic compounds comprising at least one phosphate group have the following structure: wherein X, and Z are each H ,0H, S03H, NH2, P04 or Y and W are each H , OH, SO3H, or NH2. In one embodiment, X, Y, Z, and W are H. In another embodiment, X is H, and Y, Z and W are OH. In another embodiment, X and Y are H, and Z and W are OH.
Selecting An Appropriate Light Frequency
[0187] Figure 5 is a flow chart of the technique (50) for choosing one or more light frequencies to excite specific target molecules for detection of the Raman-active products. A Raman-active product (51), such as the product (46) produced by the reaction (45) of FIG. 4, is a chemical that possesses a structure which is Raman- active. The absorbance spectrum of the product (51), is measured in step (52) using a technique such as absorbance or transmittance spectrophotometry. In step (53), one or more wavelengths are identified at which the product (51) absorbs light as seen in the spectrum measured in step (52). In step (54), a light source that emits light at a wavelength corresponding to one of the one or more wavelengths identified in step (53) is then selected. Such wavelengths can be in the visible range, ultraviolet range or infra-red range. For example, for the Listeria detection reaction (30) described for FIG. 3, the wavelength selected is 532 nm.
[0188] Finally, in step (55) the light source chosen in step (54) is used to irradiate the Raman-active product created in step (51). This will confirm that there is significant Raman scattering of the Raman-active product created in step (51) to provide adequate signal for detection. In other embodiments, the invention may be practiced using detectors other than non-single lens Raman optics detectors, such as fluorescence detectors.
[0189] Figure 6 is an illustration of a micro-fluidic channel (60) designed to detect Raman-active compounds. A source liquid (or gas) sample (61 ) including the target biological organisms or components flows through the channel (62). The target biological organisms or components will react and be bound to the reactant(s) attached to the active surface (64). Light (68) from a light source (65) produces Raman scattered light (69) which is detected by the photodetector (66). The photodetector is designed to measure one or more specific wavelengths which correspond to the Raman scattering of the combined reactant(s) and biological organism or component. It is also envisioned that instead of binding the biological organism or component to the surface (64), the reactant(s) may be released from the surface and the Raman-scattering light source (65) and detector (66) may be located downstream from the surface.
[0190] Figure 7 is an illustration of an array of micro-fluidic channels (70) designed to detect Raman-active compounds. One or more source liquid (or gas) samples (71 A), (71 B) through (71 N) which include the target biological organisms or components flow through the channels (72A), (72B) through (72N). The target biological organisms or components will react and be bound to the reactant(s) attached to the active surfaces (74A), (74B) through (74N). Light, (78A) through (78N), from the light sources, (75A) through (75N), produce Raman-scattered light, (79A) through (79N), which is detected by the photodetectors (76A) through (76N). The photodetectors are designed to measure one or more specific wavelengths which correspond to the Raman scattering of the combined reactant(s) and biological organisms or components bound to the surfaces.
[0191] The number of micro-fluidic channels in the array of micro-fluidic channels as limited by the upper-bound N, ranges from 2 to 100,000. It is also envisioned that a multiplicity of different reactants and wavelengths may be used in different channels. This would allow detection of multiple wavelengths of scattering from the same biological organism or component or it would allow the simultaneous detection of multiple different biological organisms and components. Finally instead of an array of micro-fluidic channels (70), it is envisioned that an array of micro-fluidic wells could be used to produce a 2-dimensional array of Raman-scattering detectors.
[0192] The present disclosure is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. The skilled artisan would recognize that instrumental parameters used in the methods described herein may vary in accordance with the present disclosure. Various embodiments are now described in detail. One of ordinary skill in the art would contemplate ... As used in the description and throughout the claims that follow, the meaning of "a", "an", and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.
EXAMPLES
EXAMPLE 1 : DETECTION OF LISTERIA USING BASH-UP
[0193] Figure 8 depicts Raman spectra obtained from an enzyme-linked immunoassay for the pathogenic bacteria Listeria utilizing the two-component BASH- UP chemistry, an enzyme-linked antibody, and Raman detection procedure described below utilizing the following buffers and reagents:
[0194] Working Saline Buffer (used for washes in protocol):
10 mM Sodium Phosphate, pH 6.0
137 mM Sodium Chloride
2.67 mM Potassium Chloride
0.09 mM Ethylenediaminetetraacetic acid (EDTA)
0.05% Bronidox-L
[0195] Final Chemistry Reagent (BASH):
0.588 mM 5-Aminosalicylic Acid
0.145 mM 2-Hydroxybenzyl alcohol
0.005 mM L-Ascorbic Acid
0.09. Tween-20
[0196] UP Component:
1.063 mM Urea Peroxide
Working Saline Buffer
[0197] Additional Reagents:
1. Microparticles - Anti-L/ster/a (antibody) coated magnetic microparticles at 2 million microparticles/sample upon addition.
2. Conjugate Solution - Anti-L/'ster/'a (antibody) conjugated with Horseradish Peroxidase (HRPO) at 2 μg/sample upon addition [0198] Samples of either heat-killed Listeria or a negative broth (1 ml) were subject to the following procedure. Note, the 1 ml sample may be from culture, control, swab, sponge, etc.
[0199] Procedure:
1. Add 100 μΙ of microparticles to sample.
2. Incubate 30 minutes at room temperature.
3. Capture microparticles with magnet 10 minutes.
4. Remove sample volume.
5. Add 500 μΙ Working Saline Buffer, mix 2 minutes at 1000 rpm..
6. Capture microparticles with magnet 2 minutes.
7. Remove wash volume.
8. Repeat steps 3-7 two more times for a total of 3 washes.
9. Add 200 μΙ Conjugate Solution.
10. Mix solution for 30 minutes.
1 1. Repeat wash steps 3-7 for a total of 3 washes.
12. Add 200 μΙ Final Chemistry Reagent.
13. Incubate 20 minutes with mixing at 1000 rpm.
14. Add 40 μΙ 0.5 N NaOH.
15. Mix 2 minutes at 1000 rpm.
16. Capture microparticles with magnet 2 minutes.
7. Transfer volume to cuvette for Raman signal detection.
[0200] In this procedure, the Final Chemistry Reagent was a two component
BASH-UP chemistry. The Raman signal was generally stable for ~1 hour or longer. The first component in the chemistry (BASH) contained 2-hydroxy benzyl alcohol (0.02 mg/ml), 5-amino salicylic acid (0.1 mg/ml), 0.1 % Tween-20, and ascorbic acid (1 μg/ml) in the Working Saline Buffer (pH 6.0). The second component (UP) contained urea peroxide adduct (1 mg/ml) the working Saline Buffer (pH 6.0) including EDTA (1 mM). These formulations maintained activity when refrigerated out of direct light for more than one month. Mixing the two components at a ratio of 1 UP to 10 BASH created a working solution of BASH-UP that was generally stable for one working day.
[0201 ] An aliquot of BASH-UP was added to samples containing either heat- killed Listeria or a negative broth and allowed to react for 30 minutes. The appropriate period of time will vary based on the sensitivity of detection required. 40 μΙ of 0.5 N NaOH was added to the 200 μΙ BASH-UP reaction volume to stop the reaction and render the products Raman-detectible. Alteration of the volume and concentration of the NaOH may afford greater signal stability as required by the particular assay.
[0202] Raman scattering was observed from the 240 μΙ sample using a Raman Systems R-3000 Raman spectrometer with a 532 nm laser operated at the high power setting.
EXAMPLE 2: COLORIMETRIC ASSAYS OF HORSERADISH PEROXIDASE (HRPO)
[0203] Colorimetric assays of Horseradish Peroxidase (HRPO) activity were conducted to obtain data that could be compared with the Raman-based methods. TMB develops a deep blue soluble product when reacted with horseradish peroxidase. ABTS develops a blue-green product when reacted with horseradish peroxidase.
[0204] Colorimetric assays were performed with the TMB and ABTS reactions using two different methods:
[0205] Method A (TMB): HRPO dilutions were made to measure 1000 pg to 0.0125 pg per 50 μΙ sample in phosphate-buffered saline (PBS) containing 0.1% bovine serum albumin (BSA) at pH 7.4. 50 μΙ HRPO sample per dilution was added to 200 μΙ TMB reagent and allowed to react for 15 or 30 minutes at which time 200 μΙ stop-solution (KPL Laboratories) was added. Absorbance was measured at 450 nm for each sample.
[0206] Method B (ABTS): HRPO dilutions were made to allow 1000 pg to 0.0125 pg per 50 μΙ sample in PBS at pH 7.4. 50 μΙ HRPO sample per dilution was added to 200 μΙ ABTS reagent and allowed to react for 15 or 30 minutes at which time 200 μΙ stop solution (1% SDS in water) was added. Absorbance was measured at 405 nm for each sample.
[0207] The limit of detection of HRPO for TMB was 8 pg/ml and the dynamic range was 5 to 5000 pg/ml. For ABTS, the limit of detection was 32 pg/ml and the dynamic range was 32 to 5000 pg/ml. EXAMPLE 3: FLUOROGENIC AND CHEMILUMINESCENT ASSAYS OF HRPO
[0208] Several reagents were tested: Sigma Chemiluminescent Peroxidase Substrate, Pierce Fluorogenic (Chemifluorescent) Substrate Kit, AnaSpec Sensolyte ADHP Fluorogenic Substrate, Invitrogen Molecular Probes Amplex Red Fluorogenic Substrate, and KPL Laboratories LumiGLO. Sigma and Pierce substrates did not work with HRPO in PBS or with BSA-containing buffer.
A. AnaSpec Fluorogenic ADHP Assay
[0209] AnaSpec Fluorogenic kit utilizes ADHP (10-acetyl-3,7- dihydroxyphenoxazine) to analyze peroxidase in solution whereby ADHP is oxidized in the presence of peroxidase and hydrogen peroxide. The oxidized product of ADHP (resozufin) gives pink fluorescence that can be measured at the emission wavelength of 590 nm with the excitation wavelength of 530-560 nm. An overdose of peroxidase in the assay will further convert the fluorescent resorufin to non- fluorescent resozurin to yield reduced fluorescent signal. HRPO dilutions were made to allow detection of 1 ,000,000 pg to 0.0625 pg per 50 μΙ sample were prepared in PBS at pH 7.4. The procedure was the same as described earlier for TMB and ABTS assays, and two methods were used.
[0210] Method A: ADHP Reagent and Hydrogen Peroxide were prepared per manufacturer's instructions. 500 μΙ of peroxidase solution was added to 500 μΙ ADHP reagent in a 1.5 ml plastic microcuvette. The reaction mixture was gently mixed, and incubated at room temperature for 30 min without light exposure. The fluorescent signal was measured for emission at 590 nm with excitation at 550 nm on an Ocean Optics Fluorescent Spectrometer.
[0211] Method B: Similar to Method A except 400 μΙ of each of peroxidase and ADHP reagents were used.
[0212] The sensitivity (lowest limit of detection) of the AnaSpec ADHP fluorescent assay was found to be 12.5 pg/ml of HRPO. The assay range was linear from 250 pg/ml to 0 pg/ml of HRPO.
B. Molecular Probes-lnvitrogen Amplex Red Fluorogenic Assay
[0213] Molecular Probes Fluorogenic assay kit employs Amplex Red (10- acetyl-3,7-dihydroxyphenoxazine), which is similar to AnaSpec ADHP assay. The oxidized end product of the assay with peroxidase and hydrogen peroxide is resorufin. The assay claim is 1 X 10-5 U/ml, equivalent to 10 pg/ml (1 X 10-5 ml).
[0214] HRPO dilutions made to allow detection of 1 ,000,000 pg to 0.0625 pg per 50 μΙ sample were prepared in PBS, pH 7.4. Amplex Red Reagent and
Hydrogen Peroxide were prepared per Manufacturer's instructions. 400 μΙ of peroxidase solution was added to 400 μΙ ADHP reagent in a 1.5 ml plastic microcuvette. The reaction mixture was gently mixed and incubated at room temperature for 30 min in the dark. The fluorescent signal was measured at 590 nm with excitation at 550 nm on an Ocean Optics Fluorescent spectrometer at 30 min and 35 min.
[0215] The sensitivity (lowest limit of detection) of the Molecular Probes Amplex Red Fluorescent assay was found to be 25 pg/ml of HRPO. The assay range was linear from 250 pg/ml to 0 pg/ml of HRPO.
C. LumiGLO®
[0216] LumiGLO is a luminol-based chemiluminescent substrate designed for use with peroxidase-labeled reporter molecules. In the presence of hydrogen peroxide, HRPO converts luminol to an excited intermediate dianion. This dianion emits light on return to its ground state. After reaction with HRPO conjugate, the light emission from LumiGLO reaches maximum intensity within 5 minutes and is sustained for approximately 1 - 2 hours.
[0217] The sensitivity (lowest limit of detection) of the LumiGLO in
representative experiments was found to be 11 pg/ml of HRPO.
RAMAN-BASED ASSAYS
[0218] A variety different combinations and amounts of reagents producing Raman-active products were tested to find the optimal reaction conditions for each. For these assays, 50 μΙ HRPO sample per dilution was added to 150 μΙ of the selected Raman Reagent (A-E), plus urea peroxidase in volume ratio of 9:1 , and samples allowed to react for 30 minutes. Formulations of Reagents A-E are shown in the tables below. 50 μΙ of 0.5 N NaOH was then added to each sample which was allowed to incubate for 30 minutes. Raman-based assays were also performed in HRPO samples diluted in PBS at pH 7.4. Raman spectra were recorded with a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector. Spectral analyses were based on measurement of the Raman signal at wavelength 3260 and by SQR using every 2nd wavenumber between 3500 cm"1 and 4000 cm"1.
EXAMPLE 4: RAMAN REAGENT A (BASH-UP)
[0219] The formulations used for this study are listed in Table 5:
TABLE 5: RAMAN REAGENT A
[0220] HRPO was reacted with Raman Reagent A-1 with dilution in PBS containing 0.1% BSA at pH 7.4. Raman spectra were recorded for HRPO dilutions from 0 ("blank") to 100 pg/ml. Figure 9 A shows the single peak (3260 cm"1) dependence on HRPO concentration and Figure 9 B shows the same results after applying SQR analysis (3500-4000 cm"1). Table 6 compares the detection limits of HRPO detection from different experiments, showing increased sensitivity from the SQR method compared to measurements based on a single peak.
TABLE 6: DETECTION LIMITS
[0221] HRPO was reacted in Raman Reagents A-1 , A-2, and A-3 and Raman spectra were recorded for HRPO dilutions from 0 ("blank") 5 pg/ml. Figure
10 shows the single peak (3260 cm"1) dependence on HRPO concentration. Figure
11 shows an SQR analysis of Raman Reagents A-1 and A-2 (3500-4000 cm"1).
[0222] HRPO was reacted with Raman Reagent A-2, and with fresh HPRO in BSA diluent. Figure 12 shows the single peak (3260 cm"1) dependence on HRPO concentration.
[0223] Table 7 compares the detection limits from different Raman Reagent A formulations, showing the increase in sensitivity provided by the SQR method.
TABLE 7: DETECTION LIMITS
A-1 lacking AA
Example 5: Raman Reagent B
[0224] Raman reagent formulations used for this study are listed in Table 8.
TABLE 8: RAMAN REAGENT B
[0225] HRPO was reacted in Raman Reagent B-1 , B-2, B-3, and B-4.
Raman spectra were recorded for HRPO dilutions from 0 ("blank") to 1000 pg/ml. Figure 13 show the single peak (3260 cm-1) dependence on HRPO concentration. Figure 14 shows single peak dependence on HRPO concentration and compares fresh HRPO in BSA diluent and formulation B-2
[0226] Table 9 compares the detection limits from several different Raman reagent B formulations, showing the increase in sensitivity provided by the SQR method.
TABLE 9: DETECTION LIMITS
Fresh HRPO in BSA diluent EXAMPLE 6: RAMAN REAGENT C
[0227] Raman reagent formulations used for this study are listed in Table 10. TABLE 10: RAMAN REAGENT C
[0228] HRPO was reacted in Raman Reagent C-1. Spectra were recorded for HRPO dilutions from 0 ("blank") to 1000 pg/ml. Figure 15 A shows the single peak (3260 cm"1) dependence on HRPO concentration and Figure 15 B shows the corresponding SQR spectra. Table 11 compares the detection limits for the single peak and SQR method, showing increased sensitivity from SQR.
TABLE 11 : DETECTION LIMITS
* Fresh HRPO in BSA diluent
EXAMPLE 7: RAMAN REAGENT D
[0229] Raman reagent formulations used for this study are listed in Table 12. TABLE 12: RAMAN REAGENT D
[0230] HRPO was reacted in Raman Reagent D-1. Spectra were recorded for HRPO dilutions from 0 ("blank") to 1000 pg/ml. Figure 16 A shows the single peak (3260 cm"1) dependence on HRPO concentration and Figure 16 B shows the corresponding SQR spectra.
TABLE 13: RAMAN REAGENT E
[0231] HRPO was reacted in Raman Reagent D-1. The detection limit for Raman Reagent formulation D was 50 pg/ml.
EXAMPLE 8: SENSITIVITY TESTS
[0232] Sensitivity tests of Peroxidase with different Raman Reagents were done in PBS at pH 7.4, containing BSA. The study was intended to evaluate the sensitivity in PBS without BSA. The following reagents were used in this study:
Raman Reagent A-1 : 500 pg/ml ASA; 20 pg/ml HBA; 20 pg/ml AA
Raman Reagent B-3: 250 pg/ml ASA; 25 pg/ml CDMP
Raman Reagent C-1 : 400 pg/ml ASA; 150 pg/ml NAP
[0233] HRPO dilutions made to allow 1000 pg to 0.0125 pg per 50 pi sample were prepared in PBS at pH 7.4. 50 pi HRPO sample per dilution was added to 150 μΙ reagent and allowed to react for 30 minutes. 50 μΙ of 0.5 N NaOH was then added. After incubation for 30 minutes, Raman spectra were recorded using a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector. Data were analyzed using SQR. Results from representative experiments appear in Tables 14- 18.
EXAMPLE 9: BIOTIN-ASA-UP, ASA-UP AND ASA-UP IN THE PRESENCE OF ANTI -OXIDANT AGENTS
[0234] The objectives of these studies were to evaluate the sensitivity of Peroxidase with Biotin-ASA-UP and ASA-UP, and to investigate the effect of various anti-oxidant agents on ASA-UP.
[0235] The materials used were Biotin (125 μg/π^\), and ASA (125 μg/ml) in PBS-EDTA, pH 6.0; and ASA (125 μg/ml) in PBS-EDTA, pH 6.0. Results in Figure 17 show that the Biotin-ASA-UP combination provides a sensitive assay that can detect as low as 0.00625 pg sample. ASA-UP without HBA also enables detection as low as 2 pg of HRPO.
[0236] Representative results of comparisons of the Raman-based assays appear in Tables 14-18. Raman Reagent A (increasing ASA from 100 to 250 or 500 μg/ml), Reagent B, and Biotin-ASA provide ultra sensitive peroxidase assays, compared to Reagent A-1 and Reagent C formulations. Raman-based assays provide highly sensitive detection of Peroxidase in solution, which is shown graphically in Figure 18.
[0237] Interestingly, ASA by itself provides very good sensitivity, which is increased by the addition of CDMP, Biotin and even NAP. In reactions based on A-1 in which ascorbate and HBA were omitted, the limit of detection of peroxidase was 3.9 and 4.4 pg/ml when 500 μg/ml of ASA was used and Raman signal analyzed with wave number 3,300 cm"1 and SQR, respectively. When 750 μg/ml of ASA was used, the limit of detection was 2.3 and 1.9 when the Raman signal was analyzed with wave number 3,300 cm"1 and SQR, respectively
[0238] Use of fresh HRPO, HPRO that is used within about three hours of preparation, results in greater sensitivity, and samples should not be used after storage, even at 2-8°C overnight if greater sensitivity is required. The following tables (Tables 14-18) summarize detection limits relevant to the preceding examples from representative experiments.
TABLE 14: SENSITIVITY OF RAMAN BASED ASSAY RELATIVE TO
ABTS (SQR WITH 3500-4000 CM'1)
TABLE 15: DETECTION LIMITS WITH RAMAN REAGENT FORMULATIONS
WITH HRPO IN BSA DILUENT
Peroxidase Sample/ Increase in Sensitivity
Formulations SQR
Dilution Buffer Negative from Single Peak to SQR
PBS with 0.1 %
B-1 5 pg 1 pg 5 times
BSA
PBS with 0.1 %
B-2 1 pg 0.5 pg 2 times
BSA
PBS with 0.1 %
B-3 0.5 pg 0.05 10 times
BSA
PBS with 0.1 %
B-3 BSA. Fresh 0.25 pg 0.00625 pg 40 times
HRPO
PBS with 0.1 %
B-4 2.5 pg 0.5 pg 5 times
BSA
PBS with 0.1 %
A-1 1 pg 0.5 pg 2 times
BSA
PBS with 0.1 %
A-2 1 pg 0.05 pg 20 times
BSA
PBS with 0.1 %
A-2 BSA. Fresh 0.25 pg 0.00625 pg 40 times
HRPO
PBS with 0.1 %
A-3 1 pg 1 pg No Change
BSA
PBS with 0.1 %
C-2 0.5 pg 0.1 pg 5 times
BSA
PBS with 0.1 %
C-3 BSA, Fresh 0.5 pg 0.25 pg 2 times
HRPO Peroxidase Sample/ Increase in Sensitivity
Formulations SQR
Dilution Buffer Negative from Single Peak to SQR
PBS with 0.1 %
D-1 2 pg 0.5 pg 4 times
BSA
PBS with 0.1 %
E-2 50 pg NA NA
BSA
TABLE 16: DETECTION LIMITS WITH RAMAN REAGENT FORMULATIONS
WITH HRPO IN PBS DILUENT
TABLE: 17: DETECTION LIMITS WITH COLORIMETRIC AND FLUOROGENIC
REAGENTS
Lowest
Sample/
Time of Limit of
Reaction
Formulations Peroxidase Dilution Buffer Incubation Detection
Volume
(Minutes) (pg) for 50
(Ml)
μΙ Sample
B-3 PBS with BSA 30/30 50/250 0.05
PBS with BSA, Fresh
B-3 30/30 50/250 0.00625
HRPO
PBS, pH 7.4, Fresh
B-3 30/30 50/250 0.05
HRPO
B-3 PBS , pH 7.4 30/30 50/250 0.50
C-1 PBS with 0.1 % BSA 30/30 50/250 0.10
PBS with BSA, Fresh
C-3 30/30 50/250 0.25
HRPO
C-3 PBS , pH 7.4 30/30 50/250 0.0125
PBS, pH 7.4, Fresh
C-3 30/30 50/250 0.0125
HRPO
Biotin-ASA PBS, pH 7.4, Fresh
30/30 50/250 0.00625 125/125 HRPO
[0239] Note that the Amplex Read Peroxidase assay is linear between 25 and 250 pg/50 μΙ of sample (per vendor's claim) and the assay is able to detect as low as 1x10-5 U/ml. The Sigma HRPO used in the current study had an activity of 1080 U/mg solid. On this basis, 1x10"5 U/ml HRPO is equivalent to 10 pg/ml (0.5 pg/50 μΙ).
[0240] Table 18 summarizes a representative comparison of Raman-based detection and detection by absorbance, chemiluminescence, and fluorescence.
TABLE 18: SUMMARY OF COMPARATIVE DATA Detection (Peroxidase cone, in pg/ml)
BASH-UP Raman 3-6 pg/mL 1 ,250 fold 4 to 5,000 (SQR)
TMB Detection Absorbance 8 pg/mL 125 fold 8 to 1 ,000 (A 450)
ABTS Detection Absorbance 32 pg/mL 156 fold 32 to 5,000 (A 405)
OPD Detection Absorbance 55 pg/mL 91 fold 55 to 5,000 (A 492)
LumiGLO Chemi- 11 pg/mL 455 fold 11 to 5,000 Detection luminescence
Amplex Red Fluorescence 257 pg/mL 91 fold 257 to 5,000
[0241] The effect of various anti-oxidant agents on Raman-based detection assays was examined. The effect of anti-oxidant agents on peroxidase reactions using 750μg ml ASA in representative experiments are summarized in Table 19.
TABLE 19: EFFECTS OF ANTI-OXIDANTS
EXAMPLE 10: IMMUNOASSAYS USING RAMAN-BASED DETECTION
[0242] Raman-based methods were employed to the immunoassay formats available from R&D Systems Inc. (D2050), BD Biosciences (5506111), BD
Biosciences (557825), R&D Systems Inc. (DRT200), and BioCheck Inc (BC-1105). The assay protocols were followed according to the manufacturer's instructions, with the exception that substrates producing Raman-active compounds were substituted for TMB. The experiments using Raman-active compounds were conducted as follows:
Reagent A
1. 5-Aminosalicylic Acid: 250 μg/mL
2. 2-Hydroxybenzyl Alcohol: 20 μg/mL
3. Ascorbic Acid: 0.2 μg/mL
[0243] The above three reagents were dissolved in 10 mM phosphate buffered saline with 1 mM EDTA, pH 6.0 (PBS-EDTA) and filtered through a sterile 0.45 micron cellulose nitrate filter and was stored in an amber-colored polyethylene bottle at 2-8 °C.
Reagent B
1. Urea-Peroxide: 1000 ug/mL which contains 360 ug/mL Hydrogen Peroxide [0244] The reagent was dissolved in 10 mM phosphate buffered saline with 2 mM EDTA, pH 6.0 (PBS-EDTA) and filtered through a sterile 0.45 micron cellulose nitrate filter and was stored in an amber colored polyethylene bottle at 2-8 °C.
Raman Substrate
[0245] Raman substrate was prepared by mixing Reagent A and Reagent B in a volume ratio of 9:1 prior to use. The substrate should be used in the same of preparation.
The results from representative experiments are summarized in Table 20.
TABLE 20: RAMAN-BASED IMMUNOASSAYS
[0246] Introduction of substrates producing Raman-active products into the Human IL-2 assay resulted in an approximately 5-20 fold improvement in assay sensitivity. Figure 19. The shift of the IL-2 dose response curve to the left demonstrated in Figure 19 exemplifies this improved sensitivity.
EXAMPLE 11 : ABSORBANCE. FLUORESCENCE, AND RAMAN DETECTION OF
BASH-UP AND OPD REACTIONS WITH HRPO
[0247] Studies using o-phenylenediamine as a peroxidase substrate revealed that OPD produces a Raman signal that is peroxidase dependent, does not require addition of NaOH, and can be detected over a wide range of wave numbers. The signal is more pronounced in the absence of NaOH, but is present in an altered form when the reaction is stopped with either NaOH or H2S04.
[0248] Studies were done to evaluate the fluorescence and absorption characteristics of Raman peroxidase reactions using o-phenylenediamine (OPD) and BASH-UP substrate solutions. The OPD and BASH-UP reactions were prepared according to the following procedures:
[0249] OPD protocol:
1. prepare OPD substrate solutions per SIGMAFAST™ OPD instructions;
2. prepare HRPO peroxidase dilutions in buffer (PBS-BSA) to 4,000 pg/ml;
3. prepare the OPD/peroxide substrate solution (substrate solution should be used within one hour of preparation);
4. add 250 μΙ diluted peroxidase sample to each reaction tube;
5. add 750 μΙ OPD/peroxide substrate to each tube; and
6. mix and incubate for 15 min in the dark at room temperature.
[0250] BASH-UP protocol:
1. prepare the BASH-UP substrate solution (9:1 BASH to UP, v/v);
2. add 200 μΙ of diluted peroxidase dilution to each reaction tube;
3. add 600 μΙ BASH-UP substrate solution to each tube;
4. mix and incubate for 30 min at room temperature;
5. add 200 μΙ of 0.5 N NaOH stop solution to each reaction tube; and
6. mix and incubate for 30 min at room temperature. [0251] Reactions with either BASH-UP, or OPD-peroxide reagents were performed on sample solutions containing either 0 or 2,000 pg/ml peroxidase as follows:
[0252] OPD Reactions
1. Mix 250 μΙ of 2,000 pg/ml Peroxidase + 750 μΙ OPD-peroxide substrate solution;
2. Mix 250 μΙ of 1X PBS-BSA Buffer + 750 μΙ OPD-peroxide substrate solution;
3. Add peroxidase and allow reaction to proceed in the dark.
4. Read spectrum 30 min after the reaction time has expired.
[0253] BASH Reactions
1. 200 μΙ peroxidase (at 2,000 pg/ml cone.) + 600 μΙ BASH-UP + 200 μΙ 0.5 N NaOH
2. 200 μΙ of 1X PBS-BSA buffer + 600 μΙ BASH-UP + 200 μΙ 0.5 N NaOH
3. Add peroxidase and BASH, react 30 min, stop with NaOH.
4. Read spectrum 30 min after stopping the reaction.
[0254] Absorbance. Scans were performed with a Digilab Hitachi U-2800 spectrophotometer and spectra were recorded using 0.750 ml of each reaction sample using a single beam mode. The background sample (0 pg/ml peroxidase) was used as baseline. Spectra (340 to 650 nm; 1200 nm/min scan rate; 2 nm interval) are shown in Figures 20 A and 20 B. The absorption spectra of the BASH reaction was broad covering the visible wavelength range (centered around 500 nm) lacking distinct peaks associated with a unique absorbing species (Figure 20 A). The absorption spectra of the OPD reaction was more defined (Figure 20 B), with a broad peak near 440 nm (yellow wavelength range).
[0255] Fluorescence. Scans were performed with an Ocean Optics USB 2.0 Fiber Optic lens with a 200 nm split and equipped with Spectrasuite software. Spectra were generated using excitation wavelengths of either 514 or 532 nm.
Emission spectra were collected using 12 second integration and a box width of 30. Emission spectra are shown in Figures 21 A-D. The fluorescence emission spectra of both the negative (0 pg/ml peroxidase) and reactive (2,000 pg/ml peroxidase) BASH reactions were similar (Figures 21 A and B), with a low level of inherent fluorescence. The OPD reaction fluorescence spectra were similar (Figures 22 A-D).
[0256] Raman. Spectra were collected on a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector with a 532 nm laser; spectra of each reaction are shown in Figures 30 and 31. The BASH reaction resulted in a large Raman signal (Figure 23 A). This BASH reaction had a characteristic light pink color associated with large peroxidase-containing samples. The OPD reaction also resulted in a large Raman signal (Figure 23 B), and had a characteristic yellow color also associated with large peroxidase-containing samples. No increase in
fluorescence signal was observed corresponding to the increase in Raman signal. In fact, there appeared to be a slight decrease in fluorescence signal observed when peroxidase was present. These observations were consistent at emission
wavelengths of 51 and 532 nm.
[0257] These results show that neither BASH reactions, nor OPD reactions which resulted in large peroxidase dependent Raman signals, showed large peroxidase dependent fluorescence signals. Therefore fluorescence cannot account for the Raman signals detected as a result of Peroxidase activity in the BASH or OPD reactions.
EXAMPLE 12: RAMAN SENSITIVITY OF OPD-PEROXIDASE REACTIONS AND MEASUREMENTS OF ENZYME KINETICS
[0258] Studies were done to evaluate and characterize the Raman signal associated with the OPD-peroxidase reaction. The following procedure was used for sample preparation:
[0259] OPD reaction:
1. prepare OPD substrate solutions per SIGMAFAST™ OPD instructions;
2. prepare 3M H2S04 stop solution;
3. prepare peroxidase dilutions in buffer (PBS BSA) to 4,000 pg/ml;
4. prepare the OPD/peroxide substrate solution (substrate solution should be used within one hour of preparation);
5. add 50 μΙ diluted peroxidase sample to each reaction tube;
6. add 150 μΙ OPD/peroxide substrate to each tube; 7. mix and incubate for 30 min in the dark at room temperature;
8. add 50 μΙ of 3M H2S04 stop solution, 50 μΙ 0.5 N NaOH or 50 μΙ of 1 x PBS-BSA solution to each reaction tube.
[0260] The following reaction mixtures were prepared in 5 X 60 mm cuvettes. Each mixture was prepared and measured for 30 min prior to preparation of the next reaction. Fresh OPD substrate was prepared each hour. The reactions used are shown in Table 21 :
TABLE 21 : OPD REACTIONS
[0261] Kinetic studies were performed on each reaction, collecting Raman spectra every 2 mins. Figures 24 A-E show spectra collected in approximately 5-6 min intervals.
[0262] SQR analysis was applied to the collected spectra for the following wavelength ranges: 2,000 - 2,500 cm"1; 2,500 - 3,000 cm"1; 3,000 - 3,500 cm"1; and 3,500 - 4,000 cm"1. The Raman kinetic plots of SQR spectra vs. OPD-peroxidase reaction time are shown in Figures 25 A-D. These results show that kinetic rate information may be collected from single-tube OPD-peroxidase reactions (collecting multiple Raman spectra during the course of a reaction from a single reaction tube).
[0263] The SQR values obtained after 30 minutes of reaction time were compared to the estimated rate of reaction calculated by SQR, which revealed a good correlation between these values over a wide range of wave numbers. EXAMPLE 13: RAMAN DETECTION OF PHOSPHATASE SUBSTRATES USING
OXIDIZING AGENTS
[0264] Experiments were done to study the Raman signal of products obtained from reacting alkaline phosphatase with different aromatic organic compounds having phosphate substituents. The effects of adding sodium metaperiodate as an oxidizing agent, and/or adding sodium hydroxide were also studied. The following procedure was followed:
(a) prepare a mixture comprising alkaline phosphatase
and the phosphate-containing aromatic compound as
enzyme substrate;
(b) incubate the mixture to form Raman-active products;
(i) (optional) add sodium metaperiodate as an oxidizing agent;
(ii) (optional) add sodium hydroxide;
(c) detect the Raman-active products with Raman
spectroscopy.
[0265] Raman spectra were collected in the range 0-4000 cm"1 with a Sword Diagnostics Raman Systems INC QE 65000 Raman Detector equipped with a 532 nm laser. The compounds examined were benzoquinone, pyrogallol, 1 ,4- naphthaquinone, and 1 ,4-iminonaphthaquinone.
[0266] Figure 26 A shows Raman spectra of benzoquinone as a function of adding strong NaOH solution 0.5 N where the added NaOH causes enhanced Raman signal. This enhancement was found to be reversible, where addition of an acid decreased the signal and re-addition of NaOH again increased the signal. Figure 26 B shows Raman spectra of pyrogallol (1 ,2,3-trihydroxybenzene) also as a function of added NaOH. Pyrogallol exemplifies an aromatic (phenyl) structure hydroxylated in the ortho (1 ,2) position.
[0267] The effect of added sodium metaperiodate was also studied. Figure 27 A shows Raman spectra of 1 ,4-naphthaquinone as a function of both NaOH and periodate. Figure 27 B similarly shows Raman spectra of 1 ,4-iminonaphthaquinone. These plots indicate that such compounds undergo rapid auto-oxidation to generate Raman signal. 1 ,4-naphthaquinone (Figure 27 A) shows very high signal with or without periodate without the presence of NaOH. The spectral pattern changes with the addition of NaOH and showed reduced signal. On the other hand, 1 ,4- iminonaphthaquinone (Figure 27B) shows enhanced Raman signal without periodate in the presence of NaOH. This compound shows reduced signal with periodate in the presence of NaOH, possibly due to further oxidation of imino function in this compound. The Raman signal of 1 ,4-iminoquinone could not be generated without NaOH (Figure 27 B (d and e).
EXAMPLE 14: EXEMPLARY PHOSPHATASE-BASED RAMAN IMMUNOASSAY REAGENTS AND PROCEDURES
[0268] The following describes exemplary reagents and procedures that can be used in phosphatase-based immunoassays.
Raman substrates
■ 4- Amino-1-phenyl-1-phosphate
■ 4-Hydroxy-1-naphthyl-1 -phosphate
■ 4-Amino-1-naphthyl-1 -phosphate
■ Hydroquinone diphosphate
Enzymes
■ Alkaline phosphatase from calf intestine (Sigma)
■ Goat anti-human IgG (H+L) alkaline phosphatase conjugate (KPL) (contains protein stabilizer and
sodium azide as a preservative)
Substrate Buffers
■ 0.2 M TRIS (4-amino-2-hydroxymethylpropane- 1 ,3-diol) with 5 mM MgCI2, pH 9.8
■ 1 M diethanolamine with 0.50 mM MgCI2, pH 9.8
Enzyme Storage Buffer: 10 mM TRIS buffer, 50 mM KCI, 1 mM MgCI2, 0.1 mM ZnCI2, 50% glycerol, pH 8.2. Coating Buffer: 50 mM sodium carbonate-bicarbonate buffer, pH 9.4
Blocking Buffer: 50 mM TRIS buffer, pH 8.0 with 2% BSA (bovine serum albumin) with 0.05% Tween 20, pH 8.0
Assay Buffer: 50 mM TRIS buffered Saline with 0.1% BSA and 1 mM MgCI2, pH 9.0
Wash Buffer: 50 mM TRIS buffered saline with 0.05% Tween 20, pH 8.0
[0269] Procedure A: An immunoassay of 4-aminophenyl phosphate is prepared as follows:
1. Dilute alkaline phosphatase (0-1000 pg/mL) in assay buffer
2. Take 50 pL of diluted alkaline phosphatase
3. Add 150 μΙ_ of substrate solution (200 pg/mL)
4. Incubate for 1 hour at room temperature
5. Add 50 μΙ_ of 0.5 N NaOH
6. Incubate for 30 mins at room temperature
7. Record Raman spectrum
[0270] Procedure B: Immunoassays of hydroquinone diphosphate, 4- hydroxynaphthyl phosphate, and 4-aminonaphthyl phosphate are prepared as follows:
1. Dilute alkaline phosphatase (0-1000 pg/mL) in assay
buffer
2. Take 50 pL of diluted alkaline phosphatase
3. Add 150 μΙ_ of substrate solution (100-200 pg/mL)
4. Incubate for 1 hour at room temperature 5. Add 50 pL of 0.5 mg/mL freshly-prepared sodium metaperiodate solution in water
6. Incubate for 30 mins at room temperature
7. Add 50 pL of 0.5 N NaOH
8. Incubate for 30 mins at room temperature
9. Record Raman spectrum
EXAMPLE 15: MICROTITER PLATE IMMUNOASSAY
[0271] The procedure for preparing a microtiter plate immunoassay for a generic Antigen "A" is described by the following.
1. Coating: Add 100 pL/ mL per well of the capture antibody specific to generic Antigen A to the 96-well ELISA plate at a concentration of 5-10 μg/mL; incubate 2- 3 hours at room temperature.
2. Blocking: Empty the plate. Add 200 μΙ of blocking buffer and incubate for 1 hour at room temperature.
Empty the plate and blot the plate on a stack of
paper towels. The plate can be stored at 4°C for
future use or can be used immediately.
3. Washing: Wash the plate with 300 pL of wash buffer per well 5 times. Blot the plate after the last wash on a stack of paper towels.
4. Add Sample: Add 50-100 pL of sample containing
Antigen A per well (standards as well as samples to be tested). Incubate for 1 hour at room temperature on a plate shaker. Samples should be freshly diluted in the assay buffer before adding to the plate.
5. Washing: Repeat step (3). 6. Add Enzyme-conjugated Secondary Antibody: Dilute
alkaline phosphatase conjugated antibody specific to Antigen A in assay buffer to approximately 1
pg/mL. Add 100 μΙ_ to each well. Incubate for 1
hour at room temperature on a plate shaker.
7. Washing: Repeat step (3), washing each well 7 times.
8. Add Substrate: Add 150 μΙ_ of substrate solution to each well. Incubate for 30 mins at room temperature on a plate shaker.
9. Oxidation of Substrate (optional): Add 50 to 100 μΙ_ of
freshly-prepared sodium metaperiodate (0.5
mg/mL in water). Incubate for 1 hour at room
temperature on a plate shaker.
10. Add Raman-Active Trigger or Enhancer (optional): Add
50 μΙ_ of 0.5 N sodium hydroxide to each well.
Incubate for 30 mins at room temperature on a
plate shaker.
11. Record Raman Spectrum.
EXAMPLE 16: COLORIMETRIC DETECTION OF ALKALINE PHOSPHATASE CONJUGATE WITH OXIDIZING AGENT
[0272] Alkaline phosphatase was analyzed via colorimetry using p- nitrophenylphosphate as the substrate.
[0273] Materials
■ Alkaline phosphatase conjugate:
- Goat anti-human IgG (H&L) conjugated to
alkaline phosphatase (KPL INC.,
Gaithersburg, MD) Purified antibody = 0.10 mg; Molar ratio
enzyme/antibody = 1.7:1
- Dissolve in 1 mL of distilled water (100 pg/mL) - Store frozen in 50 μΙ_ aliquots at -20° C
■ DEA buffer (1.0 M diethanolamine with 0.5 mM MgCI2 pH
9.8)
■ p-Nitrophenylphosphate (Sigma Chemical, St. Louis, MO)
[0274] Preparation of reagents
■ Alkaline phosphatase conjugate dilutions prepared in
DEA buffer for concentrations 0.001 -100 ng/mL
■ p-Nitrophenylphosphate solution prepared in DEA buffer,
1 mg/mL
[0275] Colorimetric assay procedure
1. Add 50 iL of alkaline phosphatase conjugate to
plastic microcuvette.
2. Add 200 [iL of p-Nitrophenylphosphate solution.
3. Mix on a Vortex mixer.
4. Incubate for 30 minutes at room temperature.
5. Read absorbance at 405 nm on a spectrophotometer.
[0276] A linear dependence of absorbance on alkaline phosphatase conjugate was observed at low concentrations (0-10 ng/mL). The limit of detection was approximately 0.25 ng/mL.
EXAMPLE 17: RAMAN DETECTION OF ALKALINE PHOSPHATASE
CONJUGATE WITH OXIDIZING AGENT
[0277] Alkaline phosphatase was analyzed via Raman spectroscopy using 4- aminophenylphosphate as the substrate, with oxidizing agent (sodium
metaperiodate).
[0278] Materials
■ Alkaline phosphatase conjugate (see Ex. 16)
■ DEA buffer
■ Sodium metaperiodate ■ 4-Aminophenylphosphate sodium salt (Alexis
Biochemicals, San Diego, CA)
[0279] Preparation of reagents
■ Alkaline phosphatase conjugate dilutions prepared
according to Ex. 15
■ Sodium metaperiodate solution prepared in water, 5
mg/mL
■ 4-Aminophenylphosphate solution prepared in DEA
buffer, 1 mg/mL
[0280] Raman assay procedure
1. Add 50 L alkaline phosphatase conjugate to glass
cuvette.
2. Add 200 L of 4-Aminophenylphosphate solution.
3. Mix on a Vortex mixer.
4. Incubate for 30 minutes at room temperature.
5. Add 50 μΐ of sodium metaperiodate solution.
6. Mix on a Vortex mixer.
7. Incubate for 30 minutes at room temperature.
8. Record Raman spectrum (0-4000 cm"1).
[0281] Raman data appear in Table 22: TABLE 22: RAMAN DETECTION OF ALKALINE PHOSPHATASE CONJUGATE
3 0.001 531 520 15.70 3.02 Negative 1.024
4 0.001 509
5 0.01 515 517 3.34 0.65 Negative 1.019
6 0.01 520
7 0.10 515 508 9.98 1.96 Negative 1.001
8 0.10 501
9 1.00 558 560 1.89 0.34 Positive 1.102
10 1.00 561
11 10 805 824 26.42 3.21 Positive 1.622
12 10 842
13 100 2,644 2603 56.92 2.19 Positive 5.128
14 100 2,563
15 1 ,000 2,569 2542 38.47 1.51 Positive 5.007
16 1 ,000 2,515
"Positive" refers to samples whose mean Raman signal recorded at 3300 cm"1 was greater than the negative mean signal recorded at 3300 cm"1 (+ 2 SD). CV = coefficient of variation: SD = standard deviation; S/N = signal to noise.
[0282] Figure 28 A is a logarithmic plot of Raman spectral values at
3300 cm"1 recorded for 4-aminophenylphosphate as a function of alkaline
phosphatase conjugate concentration with the addition of oxidizing agent, and Figure 28 B shows the linear plot.
[0283] Figure 29 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase conjugate concentration ranging from 0-1000 ng/mL with the addition of oxidizing agent, while Figure 29 B shows the range 0-10 ng/mL. The limit of detection was approximately 0.25 ng/mL.
EXAMPLE 18: COLORIMETRIC DETECTION OF ALKALINE PHOSPHATASE WITHOUT OXIDIZING AGENT
[0284] Alkaline phosphatase was analyzed via colorimetry using p- nitrophenylphosphate as the substrate.
[0285] Materials
■ Alkaline phosphatase: - Calf intestine (Sigma Chemical, St. Louis, MO)
Concentration: 10,000 Units/mL
- Storage buffer (10 mM TRIS, 50 mM KCI, 1 mM
MgCI2, 0.1 mM ZnCI2 in 50% glycerol,
pH 8.2)
- 500 Units/50 μΙ_ stored in total 2.0 ml. storage
buffer
- 100 pL aliquots stored frozen at -20°C
- Concentration of each aliquot: 250 U/mL
■ DEA buffer
■ p-Nitrophenylphosphate
[0286] Preparation of reagents
■ Alkaline phosphatase dilutions prepared in DEA buffer for concentrations 0.0025-2,500 mU/mL
■ p-Nitrophenylphosphate solution prepared in DEA buffer,
1 mg/mL
[0287] Colorimetric assay
1. Add 50 μΐ_ of alkaline phosphatase to plastic
microcuvette.
2. Add 200 μΙ_ of p-Nitrophenylphosphate solution.
3. Mix on a Vortex mixer.
4. Incubate for 30 minutes at room temperature.
5. Read absorbance at 405 nm on a spectrophotometer.
[0288] A linear dependence of absorbance on alkaline phosphatase was observed at low concentrations (0-25 mU/mL). The limit of detection was approximately 0.10 mU/mL. EXAMPLE 19: RAMAN DETECTION OF ALKALINE PHOSPHATASE WITHOUT OXIDIZING AGENT
[0289] Alkaline phosphatase was analyzed via Raman spectroscopy using 4- aminophenylphosphate as the substrate, without oxidizing agent.
[0290] Materials
■ Alkaline phosphatase (see Ex. 18)
■ DEA buffer
■ Sodium metaperiodate
■ 4-Aminophenylphosphate sodium salt (Alexis
Biochemicals, San Diego, CA)
Preparation of reagents
Alkaline phosphatase dilutions prepared according to Ex.
18
4-Aminophenylphosphate solution prepared in DEA
buffer, 2.0 mg/mL
[0292] Raman assay procedure
1 . Add 50 iL alkaline phosphatase to glass cuvette.
2. Add 150 pL of 4-aminophenylphosphate solution.
3. Mix on a Vortex mixer.
4. Incubate for 30 minutes at room temperature.
5. Record Raman spectrum (0-4000 cm"1)
[0293] Raman data appear in Table 23.
TABLE 23: RAMAN DETECTION OF ALKALINE PHOSPHATASE
"Positive" refers to samples whose mean Raman signal recorded at 3300 cm"1 was greater than the negative mean signal recorded at 3300 cm'1 (+ 2 SD). CV = coefficient of variation: SD = standard deviation; S/N = signal to noise. [0294] Figure 30 A is a logarithmic plot of Raman spectral values at 3300 cm"1 recorded for 4-aminophenylphosphate as a function of alkaline phosphatase concentration; Figure 30 B shows the linear plot. Figure 31 A shows Raman spectra of 4-aminophenylphosphate as a function of alkaline phosphatase concentration ranging from 0-2500 mU/mL, while Figure 31 B shows the range 0-25 mU/mL. The limit of detection was approximately 1 mU/mL.
EXAMPLE 20: RAMAN DETECTION OF FREE PEROXIDASE USING A SINGLE LENS RAMAN OPTICS BASED DETECTOR AND A FLUORESCENCE-BASED DETECTOR
[0295] Reagents:
• Horseradish peroxidase (HRPO) (Sigma Chemicals) was prepared by diluting serially in 50 mM imidazole, 50 mM phosphate, and 3 mM EDTA at pH 6.5 containing 0.1 % BSA.
• 5-aminosalicyclic acid and stabilized peroxide was prepared in a buffered solution (50 mM Imidazole, 50 mM Sodium
Phosphate, 3 mM Disodium Ethylenediaminetetraacetic acid (EDTA), pH 6.5).
[0296] Procedure:
1. 50 μί of each HRPO dilution was added to the wells of a 96 well plate.
Negative control: reaction components with 0 pg/ml HRPO in 50 mM Imidazole, 50 mM phosphate, and 3 mM EDTA at pH 6.5 containing 0.1% BSA.
2. 150 μΐ of the 5-aminosalicyclic solution was added to each well.
3. The plate was incubated at room temperature for 15 minutes.
4. 50 μΐ of stop solution (0.133 N NaOH) was added.
5. The plate was incubated at room temperature for 30 minutes. 6. The plate was read in the indicated detectors.
[0297] Detectors:
• Single lens Raman optics based spectroscopic detector
("Raman").
• Fluorescence channel microplate reader (Tecan Infinite0
M1000) ("Tecan fluorescence detector") set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
[0298] Run Protocol:
Label: 530 EM SCAN
Mode Fluorescence Top Reading
Emission Wavelength Start 580 nm
Emission Wavelength End 800 nm
Emission Wavelength Step Size 10 nm
Emission Scan Number 25
Excitation Wavelength 530 nm
Bandwidth (Em) 280...850: 20 nm
Bandwidth (Ex) (Range 1 ) 230.. 300: 5 nm
Bandwidth (Ex) (Range 2) 301...850: 10 nm
Gain 150 Manual
Number of Flashes 25
Flash Frequency 100 Hz
Integration Time 20 MS
Lag Time 0 MS
Settle Time 0 ms
Z-Position (Manual) 21000 Mm
[0299] Data Analysis:
[0300] Each sample concentration was measured in multiple replicates. The mean signal of the replicates was plotted against the concentration, and the resulting curve was fitted to a four parameter logistics (4PL) curve using the following equation:
(A - D)
Y = D + Y = Assay Output (Raman Signal, Absorbance)
X = Sample Concentration
1 + A, B, C and D = 4PL Curve Parameters
The analytical limit of detection (LOD) was estimated as the concentration read from the fitted 4PL curve corresponding to the mean signal of the negative control + 2 standard deviation (SD) units (associated with the negative measurement). This evaluation included: evaluation of the shape of the standard curve, estimation of the LOD, and graphical estimation of standard curve shift due to Raman detection. [0301] The Raman signal was measured as: (i) the matnitude of the shifted backscatter signal at a single Raman shift number at 3,200 cm"1 (Raman SV); (ii) a sample to negative ratio of the measured values (S/N); or (iii) an "area under the curve" measurement designated as "single quantifiable result" or "SQR" value. The latter value quantitates the difference between the Raman spectra of a reactive sample and its respective background (negative sample) over a specified Raman shift range.
[0302] Results:
• Emission spectra detected using the Tecan fluorescence detector are shown in Figure 32 (complete concentration range) and Figure 33 (lower concentration range).
• Spectral signals detected using the Tecan fluorescence
detector at different wavelengths are shown in Figure 34.
• A comparison between the peroxidase dose response curves detected with the Raman detector (SV) and the Tecan fluorescence detector are shown in Figure 35.
• A comparison between the peroxidase dose response curves detected with the Raman detector (SQR) and the Tecan fluorescence detector are shown in Figure 36.
[0303] These results demonstrate that Raman scattering can be measured with a non-laser-based light source and that Raman SV and SQR detection values are equivalent when measured with such a reader.
EXAMPLE 21 : RAMAN DETECTION OF A PEROXIDASE-BASED ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) USING A SINGLE LENS RAMAN OPTICS BASED DETECTOR AND A FLUORESCENCE-BASED DETECTOR
[0304] Reagents:
• Human Tumor Necrosis Factor-a (TNF-a) ELISA kit
(Invitrogen, Catalog No. KHC 3011). • 5-aminosalicyclic acid and stabilized peroxide was prepared in a buffered solution (50 mM Imidazole, 50 mM Sodium
Phosphate, 3 mM Disodium Ethylenediaminetetraacetic acid (EDTA), pH 6.5).
[0305] Procedure:
1. ELISA was performed as indicated in package insert
instructions through the final conjugate incubation and appropriate washes.
2. The detection step was performed as set forth in Example 20 "Procedure."
[0306] Detectors, Run Protocol, and Data Analysis: see Example 20.
[0307] Results:
• A comparison between the TNF-a dose response curves
detected with the Raman detector (SV) and the Tecan fluorescence detector at 680 nm are shown in Figure 37.
• A comparison between the TNF-a dose response curves
detected with the Raman detector (SV) and the Tecan fluorescence detector at 690 nm are shown in Figure 38.
[0308] This experiment shows that the results are equivalent when measured with Raman SV and SQR and with a non-laser-based device at emission wavelength at both 680 & 690 nm.
EXAMPLE 22: COMPARISON BETWEEN RAMAN DETECTION OF A
PEROXIDASE-BASED ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) USING A FLUORESCENCE-BASED DETECTOR AND A COLORIMETRIC ASSAY
[0309] Reagents: see Example 20.
[0310] Procedure:
• For colorimetric samples: ELISA was performed as indicated in package insert instructions. • For Raman samples: ELISA was performed as set forth in Example 21.
[0311] Detector:
• Fluorescence channel microplate reader (Tecan Infinite®
M1000) set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
• Biotek Synergy 2 Multi -detection Microplate Reader for
measuring TMB.
[0312] Run Protocol and Data analysis: see Example 20.
[0313] Results:
• A comparison between the TNF-a dose response curves
detected by the tetramethyl benzidnine (TMB) colorimetric assay and the Tecan fluorescence detector at 690 nm are shown in Figure 39.
[0314] These results demonstrate the improved sensitivity of the reagents of the invention, as indicated by the leftward shift of the curve for the Raman samples compared to the colorometic samples.
EXAMPLE 23: RAMAN DETECTION OF FREE ALKALINE PHOSPHATASE USING A SINGLE-LENS-RAMAN-OPTICS-BASED DETECTOR AND A
FLUORESCENCE-BASED DETECTOR
[0315] The objective of this study was intended to demonstrate the use of a single-lens-Raman-optics-based detector and a fluorescence-based detector with increasing concentrations of alkaline phosphatase.
[0316] Reagents:
• Alkaline phosphatase:
• Calf intestine (Sigma Chemical, St. Louis, MO)
• Concentration: 10,000 Units/mL • Storage buffer (10 mM Tris, 50 mM KCI, 1 mM MgCI2, 0.1 mM ZnCI2 in 50% glycerol, pH 8.2)
• 500 Units/50 μΐ_ stored in total 2.0 ml. storage buffer
• 100 μΙ_ aliquots stored frozen at -20°C
• Concentration of each aliquot: 250,000 mU/mL DEA buffer:
• 1.0 M diethanolamine with 1.0 mM MgCI2, and 0.1 mM ZnCI2 pH 9.8 (DEA) used for dilution of phosphate substrates
• 1.0 M diethanolamine with 1.0 mM MgCI2 and 0.1 mM ZnCI2 pH 9.8 (DEA) containing 0.1% BSA used for dilution of alkaline phosphatase
4-aminoaphthylphosphate (4-ANP) synthesized according to the procedure in Masson et al., Talanta, 64:174-180 (2004).
Procedure:
• 50 μΐ_ of each alkaline phosphatase dilution was added to the wells of a 96 well plate.
• Negative control: reaction components with 0 pg/mL alkaline phosphatase DEA buffer containing 0.1 % BSA.
• 150 μΐ_ of the 4-naphthylphosphate solution in DEA buffer (0.75 mg/mL) was added to each well.
• The plate was incubated at room temperature for 60 minutes.
• 50 μΐ_ of stop solution (0.7 N NaOH) was added.
• The plate was incubated at room temperature for 60 minutes.
• The plate was read in the indicated detectors. [0318] Detectors:
• Fluorescence channel microplate reader (Tecan Infinite®
M1000) set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
• Single lens Raman optics based spectroscopic detector
("Raman")
[0319] Run Protocol
Label: 530 EM Scan
Mode Fluorescence Top Reading
Emission Wavelength Start 580 nm
Emission Wavelength End 800 nm
Emission Wavelength Step Size 10 nm
Emission Scan Number 23
Excitation Wavelength 530 nm
Bandwidth (Em) 280...850: 20 nm
Bandwidth (Ex) (Range 1) 230...300: 2.5 nm
Bandwidth (Ex) (Range 2) 301...850: 5 nm
Gain 150 Manual
Settle Time 0 ms
Z-Position (Manual) 21000 μιτι
[0320] Data analysis:
[0321] Each sample concentration was measured in multiple replicates. The mean signal of the replicates was plotted against the concentration, and the resulting curve was fitted to a four parameter logistics (4PL) curve using the following equation:
I = V + Y = Assay Output (Raman Signal, Absorbance)
X = Sample Concentration
A, B, C and D = 4PL Curve Parameters
[0322] The analytical limit of detection (LOD) was estimated as the concentration read from the fitted 4PL curve corresponding to the mean signal of the negative control + 2 standard deviation (SD) units (associated with the negative measurement). This evaluation included: evaluation of the shape of the standard curve, estimation of the LOD, and graphical estimation of standard curve shift due to Raman detection.
[0323] The Raman signal was measured as: (i) the magnitude of the shifted backscatter signal at a single Raman shift number at 1583 cm"1 (Raman SV); (ii) a sample to negative ratio of the measured values (S/N); or (iii) an "area under the curve" measurement designated as "single quantifiable result" or "SQR" value (1500- 2501 cm-1). The latter value quantitates the difference between the Raman spectra of a reactive sample and its respective background (negative sample) over a specified Raman shift range.
[0324] Results:
• Figure 40 shows the response of alkaline phosphatase on Tecan fluorescence detector at different wavelengths. The data indicated highest signal at 580 nm.
Table 24 shows the mean Tecan signal at 580 nm TABLE 24
Tecan Results at 580 nm
Alk Phos Mean 580
SD N %CV SE Mean S/N (mU/mL) nm
0.00 517 58 4 11.3 29 1.00
0.30 879 113 4 12.8 56 1.70
0.60 1 ,111 70 4 6.3 35 2.15
1.20 2,484 304 4 12.2 152 4.80
2.40 5,282 239 4 4.5 120 10.22
4.90 14,265 3,433 4 24.1 1 ,716 27.59
9.80 20,839 1 ,651 4 7.9 825 40.31
19.50 34,666 4,828 3 13.9 2,788 67.05
Tables 25 and 26 show the results derived from the same microtiter plate on a Raman reader.
TABLE 25
Raman Results at SV 1583 cm-1
Alk Phos Mean Mean
SD N %CV SE
(mU/mL) SV S/N
0.00 1 ,873 433 4 23.1 217 1.00
0.30 2,154 249 4 11.6 125 1.15
0.60 2,733 185 4 6.8 92 1.46
1.20 4,925 283 4 5.7 142 2.63
2.40 13,338 2,421 4 18.2 1 ,211 7.12
4.90 33,739 9,085 4 26.9 4,542 18.01
9.80 58,663 4,307 4 7.3 2,154 31.32
19.50 64,494 0 4 0.0 0 34.43
TABLE 26
Raman SQR Results (1500-2501)
Alk Phos Mean Mean
SD N %CV SE
(mU/mL) SQR S/N
0.00 4,880 7,701 4 157.8 3,850 1.00
0.30 6,279 4,268 4 68.0 2,134 1.29
0.60 13,833 2,068 4 14.9 1 ,034 2.83
1.20 41 ,358 4,210 4 10.2 2,105 8.47
2.40 146,415 29,154 4 19.9 14,577 30.00
4.90 403,321 114,082 4 28.3 57,041 82.64
9.80 733,237 57,577 4 7.9 28,789 150.24
19.50 1 ,021 ,495 48,727 4 4.8 24,363 209.30
[0325] These results demonstrate that alkaline phosphatase can be quantitated using a laser-based Raman reader at an excitation of 530 nm and read as SV 1583 cm"1 and SQR at 1500-2501 cm"1 as well as with a non-laser-based reader at an excitation of 530 nm and measured at wavelength at 580 nm.
EXAMPLE 24: RAMAN DETECTION OF FREE ALKALINE PHOSPHATASE USING A SINGLE-LENS-RAMAN-OPTICS-BASED DETECTOR AND A
FLUORESCENCE-BASED DETECTOR
[0326] The objective of this study was intended to evaluate optimum wavelength for detection of alkaline phosphatase using a single-lens-Raman-optics- based detector and a fluorescence-based detector.
[0327] Reagents:
• Alkaline phosphatase: • Concentration of each aliquot: 250,000 mU/mL
• DEA buffer:
• 1.0 M diethanolamine with 1.0 mM MgCI2, and 0.1 mM ZnCI2 pH 9.8 (DEA) used for dilution of phosphate substrates
• 1.0 M diethanolamine with 1.0 mM MgCI2 and 0.1 mM ZnCI2 pH 9.8 (DEA) containing 0.1 % BSA used for dilution of alkaline phosphatase
• 4-aminoaphthylphosphate (4-ANP) synthesized according to the procedure in Masson et al., Talanta, 64:174-180 (2004).
[0328] Procedure:
• 50 μΐ_ of each alkaline .phosphatase dilution was added to the wells of a 96 well plate.
• Negative control: reaction components with 0 pg/mL alkaline phosphatase DEA buffer containing 0.1 % BSA.
• 150 pL of the 4-naphthylphosphate solution in DEA buffer (0.75 mg/mL) was added to each well.
• The plate was incubated at room temperature for 60 minutes.
• 40 pL of stop solution (0.7 N NaOH) was added.
• The plate was incubated at room temperature for 60 minutes.
• The plate was read in the indicated detectors at 30, 45, ,and 60 minutes.
[0329] Detectors:
• Fluorescence channel microplate reader (Tecan Infinite®
M1000) set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan"). Single lens Raman optics based spectroscopic detector ("Raman")
[0330] Run Protocol:
Label: EM Scan
Mode Fluorescence Top Reading
Emission Wavelength Start 570 nm
Emission Wavelength End 590 nm
Emission Wavelength Step Size 2 nm
Emission Scan Number 1 1
Excitation Wavelength Start 540 nm
Excitation Wavelength End 560 nm
Excitation Wavelength Step Size 2 nm
Excitation Scan Number 1 1
Bandwidth (Em) 280...850: 5 nm
Bandwidth (Ex) (Range 1) 230...300: 2.5 nm
Bandwidth (Ex) (Range 2) 301...850: 5 nm
Gain 255 Calculated From: D6 (100%)
Number of Flashes 50
Flash Frequency 400 Hz
Integration Time 20 ps
Lag Time 0 ps
Settle Time 0 ms
Z-Position (Calculated From: D6) 21308 pm
[0331] Data analysis: see Example 23.
[0332] Results:
Figure 41 shows the results of the scan with alkaline phosphatase. This data indicated that an excitation wavelength of 550 nm ± 4 nm and emission wavelength of 580 nm ± 4 nm seem_optimum seem to be optimum for use in the measurement of alkaline phosphatase
[0333] These results demonstrate the optimization of exitation and emission wavelengths for the quantitation of alkaline phosphatase.
EXAMPLE 25: RAMAN DETECTION OF FREE ALKALINE PHOSPHATASE FROM BACTERIA AND CALF INTESTINE USING SINGLE A FLUORESCENCE- BASED DETECTOR
[0334] The objective of this study was to use 4-aminoaphthylphosphate as a substrate for quantitation of alkaline phosphatase from bacteria and calf intestine using a single-lens-Raman-optics-based detector and a fluorescence-based detector.
[0335] Reagents:
• Alkaline phosphatase:
• Concentration of each aliquot: 2500,000 mU/mL
• E. coli (Sigma Chemicals, St. Louis, MO)
• Concentration of 175,439 mU/mL in 2 N ammonium sulphate suspension
• DEA buffer:
• 1.0 M diethanolamine with 1 .0 mM MgCI2, and 0.1 mM ZnCI2 pH 9.8 (DEA) used for dilution of phosphate substrates
• 1.0 M diethanolamine with 1.0 mM MgCI2 and 0.1 mM ZnCI2 pH 9.8 (DEA) containing 0.1 % BSA used for dilution of alkaline phosphatase
• 4-aminoaphthylphosphate (4-ANP) synthesized according to the procedure in Masson et al., Talanta, 64: 174-180 (2004).
[0336] Procedure:
• 50 μΙ_ of each alkaline phosphatase dilution was added to the wells of a 96 well plate.
• Negative control: reaction components with 0 pg/mL alkaline phosphatase DEA buffer containing 0.1 % BSA.
• 150 μί of the 4-naphthylphosphate solution in DEA buffer (1 mg/mL) was added to each well.
• The plate was incubated at room temperature for 60 minutes.
40 μΙ_ of stop solution (0.7 N NaOH) was added. The plate was incubated at room temperature for 60 minutes.
The plate was read in the indicated detectors at 30, 45, ,and 60 minutes.
[0337] Detectors:
• Fluorescence channel microplate reader (Tecan Infinite®
M1000) set to read at increments of 10 nm from 580 nm to 800 nm ("Tecan").
[0338] Run Protocol:
Label:EM Scan
Mode Fluorescence Top Reading
Excitation Wavelength 552 nm
Emission Wavelength 580 nm
Excitation Bandwidth 5 nm
Emission Bandwidth 5 nm
Gain 208 Calculated From: D6 (100%)
Number of Flashes 25
Flash Frequency 100 Hz
Integration Time 20 με
Lag Time 0 με
Settle Time 0 ms
Z-Position (Calculated From: D6) 22926 μπ\
[0339] Data Analysis: see Example 23.
[0340] Results:
• The results from alkaline phosphatase from calf intestine for 45 minute reading at excitation wavelength 550 nm and emission at 580 nm is shown in Table 27 and Figure 42 (the results from 30 and 60 minutes were similar).
TABLE 27
• The results from alkaline phosphatase from E. coli for 45 minute reading at excitation wavelength 550 nm and emission at 580 nm are shown in Table 28 and Figure 43 (the results from 30 and 60 minutes were similar)
TABLE 28
• The Limit of Detection (LOD) and Limit of Quantitation (LOQ) of alkaline phosphatase from calf intestine and E. coli were calculated by 4PLC and the results are shown in Table 29 TABLE 29
LOO from PI Calf Intestine Alkaline Phosphatase after 15 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
3489.13 317.7535 9.1 % 4125 0.64
LOQ Estimate (Concentration at Mean + 10xSD) => 3.10
LOD from Pic Calf Intestine Alkaline Phosphatase after 30 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
2382.25 121.8181 5.1 % 2626 0.52
LOQ Estimate (Concentration at Mean + 10xSD) => 1.75
LOD from Plo Calf Intestine Alkaline Phosphatase after 45 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
2509.25 1 13.7789 4.5 % 2737 0.48
LOQ Estimate (Concentration at Mean + 10xSD) => 1.63
LOD from Plo Calf Intestine Alkaline Phosphatase after 45 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
2920.88 216.6409 7.4 % 3354 0.86
LOQ Estimate (Concentration at Mean + 10xSD) => 2.77
LOD from Plo Bacterial Alkaline Phosphatase after 15 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
2067.29 453.4059 21.9 % 2974 0.73
LOQ Estimate (Concentration at Mean + 10xSD) => 2.52
LOD from Plo Bacterial Alkaline Phosphatase after 30 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
1823.43 93.5073 5.1 % 2010 0.19
LOQ Estimate (Concentration at Mean + 10xSD) => 0.70
LOD from Plo Bacterial Alkaline Phosphatase after 45 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
1689.14 206.381 1 12.2 % 2102 0.60
LOQ Estimate (Concentration at Mean + 10xSD) => 1.84
LOD from Plo Bacterial Alkaline Phosphatase after 60 Min Reaction
Mean BKG SD of BKG % CV Mean + 2 x SD LOD
1566.43 52.4209 3.3 % 1671 0.25
LOQ Estimate (Concentration at Mean + 10xSD) => 0.75
[0341] These results demonstrate that 4-aminnaphthylphosphate can be suitably used for the quantitation of alkaline phosphate from bacteria as well as calf intestine in a non-laser based detector. In addition, these results show good dose responses with both alkaline phosphatases in a non-laser based detector. These results also show that the non-laser based detector provided a low Limit of Detection (LOD) and Limit of Quantitation (LOQ) as measured by 4PLC measured at different times gave similar values. EXAMPLE 26: OPTIMIZED PROCEDURE FOR USE IN QUANTITATION OF
ALKALINE PHOSPHATE AND ALKALINE-BASED ELISA METHODS
1. Add 150 ί of 4-naphthylphosphate solution in DEA buffer (1.0 mg/mL) to each well.
2. Incubate the plate at room temperature for 60 minutes.
3. Add 40 L of stop solution (0.60 N NaOH).
4. Incubate the plate at room temperature for 30-45 minutes.
5. Read the plate at excitation wavelength 550 ± 4 nm and emission at 582 ± 4 nm at 30-45 minutes using a single-lens-Raman-optics-based detector and/or a fluorescence-based detector.

Claims

CLAIMS We claim:
1. A method for detecting the activity of at least one enzyme in a sample comprising:
a) preparing a mixture comprising the sample and at least one aromatic compound comprising at least one phosphate group;
b) incubating the mixture to form at least one Raman-active product; i) optionally adding an oxidizing agent; and ii) optionally adding a base;
c) detecting the at least one Raman-active product using at least one non-laser-based light source.
2. The method of claim 1 , wherein the device comprises at least one fluorescence detection channel.
3. The method of claim 2, wherein the device detects Raman-scattered light.
4. The method of claim 1 , wherein the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH;
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH; and
Z is H, OH, CI, Br, NH2, S03H, P04, or COOH.
5. The method of claim 1 , wherein the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH;
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH; and
Z is H, OH, CI, Br, NH2, S03H, P04, or COOH.
6. The method of claim 1 , wherein the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH; and
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH.
7. The method of claim 1 , wherein the at least one aromatic compound comprises:
wherein
X is H, OH, CI, Br, N02, NH2, S03H, P04, or COOH; and
Y is H, OH, CI, Br, N02, NH2, S03H, or COOH.
8. The method of claim 1 , wherein the at least one aromatic compound comprises:
z
wherein each of X, Y, Z, and W are each independently H or OH.
9. The method of claim 1 , wherein the at least one enzyme comprises a phosphatase.
10. The method of claim 9, wherein the phosphatase is alkaline phosphatase.
1 1. The method of claim 10, wherein the alkaline phosphatase is conjugated to an antibody, avidin, streptavidin, or a biotin-binding protein.
12. The method of claim 1 , wherein the at least one aromatic compound comprises 4-amino-1-phenyl-1 -phosphate.
13. The method of claim 1 , wherein the at least one aromatic compound comprises 4-hydroxy-1 -naphthyl-1 -phosphate.
1 . The method of claim 1 , wherein the at least one aromatic compound comprises 4-amino-1 -naphthyl-1 -phosphate.
15. The method of claim 1 , wherein the at least one aromatic compound comprises hydroquinone diphosphate.
16. The method of claim 1 , wherein the base is sodium hydroxide.
17. The method of claim 1 , wherein the oxidizing agent is sodium metaperiodate.
18. A method for detecting at least one target in a sample comprising: a) preparing a mixture comprising the at least one target;
b) incubating the mixture with at least one ligand specific for the at least one target, wherein the at least one ligand comprises a phosphatase;
c) providing to the mixture at least one aromatic compound comprising a phosphate; d) incubating the mixture to form at least one Raman-active product;
i) optionally adding an oxidizing agent; and ii) optionally adding a base; and
e) detecting the at least one Raman-active product using a device that utilizes at least one non-laser-based light source.
19. The method of claim 18, wherein the at least one aromatic compound is the aromatic compound of claim 4.
20. The method of claim 18, wherein the at least one aromatic compound is the aromatic compound of claim 5.
21. The method of claim 8, wherein the at least one aromatic compound is the aromatic compound of claim 6.
22. The method of claim 18, wherein the at least one aromatic compound is the aromatic compound of claim 7.
23 The method of claim 18, wherein the at least one aromatic compound is the aromatic compound of claim 8.
24. The method of claim 18, wherein the detection system comprises a device that is capable of detecting Raman light scattering using a fluorescence detection channel.
25. The method of claim 18, wherein the at least one target is an organism.
26. The method of claim 25, wherein the organism is E. coli, Listeria, Salmonella, Vibrio, Camphelbacter, Staphylococcus, HIV, Hepatitis, Adenovirus, Rhino virus, or Human papilloma virus.
27. The method of claim 18, wherein the target is a protein, amino acids, nucleic acids, nucleotides, carbohydrates, metabolites, hormones, or metabolic intermediates.
28. The method of claim 27, wherein the protein is IL-2, C-reactive protein, Tumor Necrosis Factor Receptor II, or Human Cardiac Troponin I.
29. The method of claim 18, wherein the at least one ligand is an antibody.
30. The method of claim 18, wherein the device comprises a fluorescence detection channel.
31. The method of claim 30, wherein the device detects Raman-scattered light.
EP11714460A 2010-03-28 2011-03-28 Methods for detecting raman scattering using aromatic compounds comprising phosphate and at least one non-laser light source Withdrawn EP2553117A1 (en)

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