Classifications

• • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/52—Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/569—Immunoassay; Biospecific binding assay; Materials therefor for microorganisms, e.g. protozoa, bacteria, viruses

Definitions

• the ability to rapidly detect microorganisms is becoming an increasing problem in a wide variety of industries, includes the medical and food industries. For instance, rapid detection of a microorganism in the medical field may be crucial for proper diagnosis and treatment of an illness. Unfortunately, multiple etiologic agents may be responsible for a particular condition, thereby making it difficult to rapidly identify the cause of the condition.
• the need for selective identification of the type of microorganism is important for a variety of reasons. For example, the knowledge of which type of microorganism is present may lead one to identify the particular source of contamination and to choose an appropriate treatment. Most of the current diagnostic procedures involve culturing the microorganism for identification, a process that usually requires several days and often gives negative results.
• a method for detecting a microorganism in a sample comprises contacting the sample with an array, the array comprising a plurality of individual array addresses spaced apart in a predetermined pattern on a solid support.
• the addresses each contain a colorant so that the array produces a visually observable spectral response.
• the spectral response is detected (e.g., visually) and correlated to the presence of one or more microorganisms.
• an array for detecting a microorganism in a sample is disclosed.
• the array comprises a plurality of individual array addresses spaced apart in a predetermined pattern on a solid support.
• the addresses each contain a colorant so that the array produces a visually observable spectral response that is distinct for one or more microorganisms.
• FIG. 1 is a perspective view of an exemplary array of the present invention prior to contact with a test sample (Fig. 1A), after contact with a test sample infected with E. coli (Fig. 1 B); and after contact with a test sample infected with S. aureus (Fig. 1 C).
• the present invention is directed to a method for detecting a microorganism or class of microorganisms. More specifically, the method employs an array that contains a plurality of discrete regions (referred to as "addresses") spaced apart on a solid support in a predetermined pattern. The addresses are selected so that the array provides a distinct spectral response (e.g., pattern of colors) or "fingerprint" for a particular microorganism or class of microorganisms.
• addresses a plurality of discrete regions spaced apart on a solid support in a predetermined pattern.
• the addresses are selected so that the array provides a distinct spectral response (e.g., pattern of colors) or "fingerprint" for a particular microorganism or class of microorganisms.
• the array may provide a certain spectral response in the presence of one microorganism or class of microorganisms (e.g., gram- negative bacteria), but provide a completely different spectral response in the presence of another microorganism or class of microorganisms (e.g., gram- positive bacteria). Detection of the spectral response provided by the array may thus allow for differentiation between microorganisms.
• one microorganism or class of microorganisms e.g., gram- negative bacteria
• another microorganism or class of microorganisms e.g., gram- positive bacteria
• the array addresses contain a colorant capable of exhibiting a color change in the presence of one or more microorganisms. That is, the colorant may change from a first color to a second color, from colorless to a color, or from a color to colorless.
• colorants e.g., dyes, pigments, etc.
• pH-sensitive colorants are employed that are capable of differentiating between certain types of microorganisms. Namely, pH-sensitive colorants can detect a change in the pH of the growth medium of the microorganism.
• Bacteria may metabolize the growth medium and generate acidic compounds (e.g., CO 2 ) or basic compounds (e.g., ammonia) that lead to a change in pH.
• acidic compounds e.g., CO 2
• basic compounds e.g., ammonia
• certain microorganisms e.g., bacteria
• pH- sensitive colorants may be selected in the present invention that are tuned for the desired pH transition. In this manner, array addresses may be provided with pH- sensitive colorants that are configured to undergo a detectable color change only in the presence of microorganisms exhibiting a certain acidic/basic shift.
• Phthalein colorants constitute one class of suitable pH-sensitive colorants that may be employed in the array of the present invention.
• Phenol Red i.e., phenolsulfonephthalein
• Phenol Red exhibits a transition from yellow to red over the pH range 6.6 to 8.0. Above a pH of about 8.1 , Phenol Red turns a bright pink
• Phenol Red may also be suitable for use in the present invention, such as those substituted with chloro, bromo, methyl, sodium carboxylate, carboxylic acid, hydroxyl and amine functional groups.
• Exemplary substituted Phenol Red compounds include, for instance, Chlorophenol Red, Metacresol Purple (meta-cresolsulfonephthalein), Cresol Red (ortho- cresolsulfonephthalein), Pyrocatecol Violet (pyrocatecolsulfonephthalein), Chlorophenol Red (3',3"-dichlorophenolsulfonephthalein), Xylenol Blue (the sodium salt of para-xylenolsulfonephthalein), Xylenol Orange, Mordant Blue 3 (C.I.
• Suitable phthalein colorants are well known in the art, and may include Bromothymol Blue, Thymol Blue, Bromocresol Purple, thymolphthalein, and phenolphthalein (a common component of universal indicators).
• Chlorophenol Red exhibits a transition from yellow to red over a pH range of about 4.8 to 6.4
• Bromothymol Blue exhibits a transition from yellow to blue over a pH range of about 6.0 to 7.6
• thymolphthalein exhibits a transition from colorless to blue over a pH range of about 9.4 to 10.6
• phenolphthalein exhibits a transition from colorless to pink over a pH range of about 8.2 to 10.0
• Thymol Blue exhibits a first transition from red to yellow over a pH range of about 1.2 to 2.8 and a second transition from yellow to pH over a pH range of 8.0 to 9.6
• Bromophenol Blue exhibits a transition from yellow to violet over a pH range of about 3.0 to 4.6
• the numbers 1-8 shown in the general formula represent a location on the fused ring structure at which substitution of a functional group may occur.
• at least one of the functional groups is or contains a hydroxy (-OH) group.
• Other examples of functional groups that may be substituted on the fused ring structure include halogen groups (e.g., chlorine or bromine groups), sulfonyl groups (e.g., sulfonic acid salts), alkyl groups, benzyl groups, amino groups (e.g., primary, secondary, tertiary, or quaternary amines), carboxy groups, cyano groups, phosphorous groups, etc.
• hydroxyanthraquinones that may be used in the present invention, Mordant Red 11 (Alizarin), Mordant Red 3 (Alizarin Red S), Alizarin Yellow R, Alizarin Complexone, Mordant Black 13 (Alizarin Blue Black B), Mordant Violet 5 (Alizarin Violet 3R) 1 Alizarin Yellow GG, Natural Red 4 (carminic acid), amino-4-hydroxyanthraquinone,
• Emodin Nuclear Fast Red
• Natural Red 16 Purpurin
• Quinalizarin and so forth.
• carminic acid exhibits a first transition from orange to red over a pH range of about 3.0 to 5.5 and a second transition from red to purple over a pH range of about 5.5 to 7.0.
• Alizarin Yellow R exhibits a transition from yellow to orange-red over a pH range of about 10.1 to 12.0.
• R 2 is selected from the group consisting of aliphatic and aromatic groups
• X and Y are independently selected from the group consisting of hydrogen, halides, -NO 2 , -NH 2 , aryl groups, alkyl groups, alkoxy groups, sulfonate groups, - SO 3 H, -OH, -COH, -COOH, halides, etc.
• Particular examples of such azo compounds (or derivatives thereof) include Methyl Violet, Methyl Yellow, Methyl Orange, Methyl Red, and Methyl Green.
• Methyl Violet undergoes a transition from yellow to blue-violet at a pH range of about 0 to 1.6
• Methyl Yellow undergoes a transition from red to yellow at a pH range of about 2.9 to 4.0
• Methyl Orange undergoes a transition from red to yellow at a pH range of about 3.1 to 4.4
• Methyl Red undergoes a transition from red to yellow at a pH range of about 4.2 to 6.3.
• Arylmethanes e.g., diarylmethanes and triarylmethanes constitute still another class of suitable pH-sensitive colorants for use in the present invention.
• Triarylmethane leuco bases for example, have the following general structure: H
• R, R', and R" are independently selected from substituted and unsubstituted aryl groups, such as phenyl, naphthyl, anthracenyl, etc.
• the aryl groups may be substituted with functional groups, such as amino, hydroxyl, carbonyl, carboxyl, sulfonic, alkyl, and/or other known functional groups.
• triarylmethane leuco bases include Leucomalachite Green, Pararosaniline Base, Crystal Violet Lactone, Crystal Violet Leuco, Crystal Violet, Cl Basic Violet 1 , Cl Basic Violet 2, Cl Basic Blue, Cl Victoria Blue, N-benzoyl leuco- methylene, etc.
• diarylmethane leuco bases may include 4,4'-bis (dimethylamino) benzhydrol (also known as "Michler's hydrol"), Michler's hydrol leucobenzotriazole, Michler's hydrol leucomorpholine, Michler's hydrol leucobenzenesulfonamide, etc.
• the colorant is Leucomalachite Green Carbinol (Solvent Green 1 ) or an analog thereof, which is normally colorless and has the following structure:
• Malachite Green also known as Aniline Green, Basic Green 4, Diamond Green B, or Victoria Green B
• Malachite Green also known as Aniline Green, Basic Green 4, Diamond Green B, or Victoria Green B
• Malachite Green typically exhibits a transition from yellow to blue-green over a pH range 0.2 to 1.8. Above a pH of about 1.8, malachite green turns a deep green color.
• pH-sensitive colorants that may be employed in the array include Congo Red, Litmus (azolitmin), Methylene Blue, Neutral Red, Acid Fuchsin, Indigo Carmine, Brilliant Green, Picric acid, Metanil Yellow, m-Cresol Purple, Quinaldine Red, Tropaeolin 00, 2,6-dinitrophenol, Phloxine B, 2,4- dinitrophenol, 4-dimethylaminoazobenzene, 2,5-dinitrophenol, 1-Naphthyl Red, Chlorophenol Red, Hematoxylin, 4-nitrophenol, nitrazine yellow, 3-nitrophenol, Alkali Blue, Epsilon Blue, Nile Blue A, universal indicators, and so forth.
• Congo Red undergoes a transition from blue to red at a pH range of about 3.0 to 5.2
• Litmus undergoes a transition from red to blue at a pH range of about 4.5 to 8.3
• Neutral Red undergoes a transition from red to yellow at a pH range of about 11.4 to 13.0.
• metal complexing colorants may thus be employed in some embodiments of the present invention that undergo a color change in the presence of siderophores.
• One particularly suitable class of metal complexing colorants are aromatic azo compounds, such as Eriochrome Black T, Eriochrome Blue SE, Eriochrome Blue
• Suitable metal complexing colorants may include Alizarin Complexone, Alizarin S, Arsenazo III, Aurintricarboxylic acid, 2,2'-Bipyidine, Bromopyrogallol Red, Calcon (Eriochrome Blue Black R), Calconcarboxylic acid, Chromotropic acid, disodium salt, Cuprizone, 5-(4-Dimethylamino- benzylidene)rhodanine, Dimethylglyoxime, 1 ,5-Diphenylcarbazide, Dithizone, Fluorescein Complexone, Hematoxylin, 8-Hydroxyquinoline, 2- Mercaptobenzothiazole, Methylthymol Blue, Murexide, 1-Nitroso-2-naphthol, 2- Nitroso-1-naphthol, Nitroso-R-s
• colorants need not be capable of independently differentiating between particular microorganisms, so long as the overall spectral response provided by the array is distinct.
• colorants may also be employed that exhibit a detectable color change in the presence of a broad spectrum of microorganisms.
• Solvatochromatic colorants for instance, are believed to exhibit a detectable color change in the presence of a broad spectrum of microorganisms. More specifically, solvatochromatic colorants may undergo a color change in a certain molecular environment based on solvent polarity and/or hydrogen bonding propensity.
• a solvatochromatic colorant may be blue in a polar environment (e.g., water), but yellow or red in a non-polar environment (e.g., lipid-rich solution).
• the color produced by the solvatochromatic colorant depends on the molecular polarity difference between the ground and excited state of the colorant.
• Merocyanine colorants e.g., mono-, di-, and tri-merocyanines
• Merocyanine colorants such as merocyanine 540, fall within the donor - simple acceptor colorant classification of Griffiths as discussed in "Colour and Constitution of Organic Molecules" Academic Press, London (1976). More specifically, merocyanine colorants have a basic nucleus and acidic nucleus separated by a conjugated chain having an even number of methine carbons. Such colorants possess a carbonyl group that acts as an electron acceptor moiety. The electron acceptor is conjugated to an electron donating group, such as a hydroxyl or amino group.
• the merocyanine colorants may be cyclic or acyclic (e.g., vinylalogous amides of cyclic merocyanine colorants).
• cyclic merocyanine colorants generally have the following structure:
• merocyanine colorants typically have a charge separated (i.e., "zwitterionic") resonance form.
• Zwitterionic colorants are those that contain both positive and negative charges and are net neutral, but highly charged. Without intending to be limited by theory, it is believed that the zwitterionic form contributes significantly to the ground state of the colorant. The color produced by such colorants thus depends on the molecular polarity difference between the ground and excited state of the colorant.
• structure 2 One particular example of a merocyanine colorant that has a ground state more polar than the excited state is set forth below as structure 2.
• the charge-separated left hand canonical 2 is a major contributor to the ground state whereas the right hand canonical 2' is a major contributor to the first excited state.
• Still other examples of suitable merocyanine colorants are set forth below in the following structures 3-13.
• R is a group, such as methyl, aikyl, aryl, phenyl, etc.
• Indigo is another example of a suitable solvatochromatic colorant for use in the present invention.
• Indigo has a ground state that is significantly less polar than the excited state.
• indigo generally has the following structure 14:
• the left hand canonical form 14 is a major contributor to the ground state of the colorant, whereas the right hand canonical 14' is a major contributor to the excited state.
• Suitable solvatochromatic colorants include those that possess a permanent zwitterionic form. That is, these colorants have formal positive and negative charges contained within a contiguous ⁇ - electron system. Contrary to the merocyanine colorants referenced above, a neutral resonance structure cannot be drawn for such permanent zwitterionic colorants.
• Exemplary colorants of this class include /V-phenolate betaine colorants, such as those having the following general structure: wherein R 1 -R 5 are independently selected from the group consisting of hydrogen, a nitro group (e.g., nitrogen), a halogen, or a linear, branched, or cyclic Ci to C 2O group (e.g., alkyl, phenyl, aryl, pyridinyl, etc.), which may be saturated or unsaturated and unsubstituted or optionally substituted at the same or at different carbon atoms with one, two or more halogen, nitro, cyano, hydroxy, alkoxy, amino, phenyl, aryl, pyridinyl, or alkylamino groups.
• the ⁇ /-phenolate betaine colorant may be 4-(2,4,6-triphenylpyridinium-1-yl)-2,6-diphenylphenolate (Reichardt's dye) having the following general structure 15:
• Reichardt's dye shows strong negative solvatochromism and may thus undergo a significant color change from blue to colorless in the presence of bacteria. That is, Reichardt's dye displays a shift in absorbance to a shorter wavelength and thus has visible color changes as solvent eluent strength (polarity) increases. Still other examples of suitable negatively solvatochromatic pyridinium /V-phenolate betaine colorants are set forth below in structures 16-23:
• R is hydrogen, -C(CH 3 ) 3 , -CF 3 , or C 6 Fi 3 .
• colorants having a permanent zwitterionic form include colorants having the following general structure 24:
• n is 0 or greater
• X is oxygen, carbon, nitrogen, sulfur, etc.
• Particular examples of the permanent zwittehonic colorant shown in structure 24 include the following structures 25 - 33.
• Still other suitable solvatochromatic colorants may include, but are not limited to 4-dicyanmethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM); 6-propionyl-2-(dimethylamino)naphthalene (PRODAN); 9-(diethylamino)-5H- benzo[a]phenox-azin-5-one (Nile Red); 4-(dicyanovinyl)julolidine (DCVJ); phenol blue; stilbazolium colorants; coumahn colorants; ketocyanine colorants; N 1 N- dimethyl-4-nitroaniline (NDMNA) and N-methyl-2-nitroaniline (NM2NA); Nile blue; 1-anilinonaphthalene-8-sulfonic acid (1 ,8-ANS), and dapoxylbutylsulfonamide (DBS) and other dapoxyl analogs.
• DCM 4-dicyanmethylene-2-methyl-6-(p
• colorants include, but are not limited to, 4-[2-N-substituted-1 ,4-hydropyridin-4-ylidine)ethylidene]cyclohexa- 2,5-dien-1-one, red pyrazolone colorants, azomethine colorants, indoaniline colorants, and mixtures thereof.
• colorants are classified based on their mechanism of color change (e.g., pH sensitive, metal complexing, or solvatochromatic), it should be understood that the present invention is not limited to any particular mechanism for the color change. Even when a pH-sensitive colorant is employed, for instance, other mechanisms may actually be wholly or partially responsible for the color change of the colorant. For example, redox reactions between the colorant and microorganism may contribute to the color change.
• mechanism of color change e.g., pH sensitive, metal complexing, or solvatochromatic
• individual array addresses may be configured in a variety of ways to accomplish this purpose.
• individual array addresses may contain colorants that each exhibits a spectral response in the presence of a microorganism.
• one array address may employ a pH-sensitive colorant that undergoes a color change at acidic pH levels, while another array address may contain a pH-sensitive colorant that undergoes a color change at neutral or basic levels.
• the array addresses may simply contain different chemical classes of colorants, irrespective of the mechanism by which they change color.
• a first array address may contain a phthalein colorant
• a second array address may contain an aromatic azo colorant
• a third array address may contain an anthraquinone colorant
• a fourth array address may contain an arylmethane colorant.
• the spectral distinction between individual array addresses need not always be provided by the use of different colorants.
• the same colorants may be used in individual array addresses, but at a different concentration so as to produce a different spectral response.
• Certain addresses may likewise contain the same colorant at the same concentration, so long as the array as whole is capable of producing a distinct spectral response.
• the array may be selectively controlled to enhance its ability to provide a distinct spectral response.
• One factor that influences the ability of the array to produce a distinct spectral response is the number of array addresses employed. Namely, a greater number of individual array addresses may enhance the degree that the spectral response varies for different microorganisms. However, an overly large number of addresses can also lead to difficulty in visually differentiating between spectral responses.
• the array contains from 2 to 50 array addresses, in some embodiments from 3 to about 40 array addresses, and in some embodiments, from 4 to 20 array addresses. The number of addresses employed in the array will ultimately depend, at least in part, on the nature of the selected colorants.
• a larger number of addresses may be needed to provide the desired spectral response.
• Another aspect of the array that may influence its ability to provide a distinctive spectral response is the pattern (e.g., size, spacing, alignment, etc.) of the individual array addresses.
• the individual array addresses may possess a size effective to permit visual observation without unduly increasing the size of the solid support.
• the width (or diameter) of the addresses may, for example, range from about 0.01 to about 100 millimeters, in some embodiments from about 0.1 to about 50 millimeters, and in some embodiments, from about 1 to about 20 millimeters.
• the shape of the addresses may also enhance visual observation of the spectral response.
• the addresses may be in the form of stripes, bands, dots, or any other geometric shape.
• the addresses may also be spaced apart a certain distance to provide a more visible spectral response.
• the spacing between two or more individual array addresses may, for example, range from about 0.01 to about 100 millimeters, in some embodiments from about 0.1 to about 50 millimeters, and in some embodiments, from about 1 to about 20 millimeters.
• the overall pattern of the array may take on virtually any desired appearance.
• Fig. 1A an array 81 is provided that contains sixteen (16) individual addresses 83 in the form of dots spaced apart in four (4) separate rows and columns.
• each of the addresses 83 includes a colorant.
• a set of first addresses 83a may include colorants that undergo a color change in the presence of E. coli and a set of second addresses 83b may include colorants that undergo a color change in the presence of S. Aureus.
• the array of the present invention is formed on a solid support, which is subsequently contacted with the test sample of interest.
• the solid support may be formed from any of a variety materials, such as a film, paper, nonwoven web, knitted fabric, woven fabric, foam, glass, etc.
• the materials used to form the solid support may include, but are not limited to, natural, synthetic, or naturally occurring materials that are synthetically modified, such as polysaccharides (e.g., cellulose materials such as paper and cellulose derivatives, such as cellulose acetate and nitrocellulose); polyether sulfone; polyethylene; nylon; polyvinylidene fluoride (PVDF); polyester; polypropylene; silica; inorganic materials, such as deactivated alumina, diatomaceous earth, MgSO 4 , or other inorganic finely divided material uniformly dispersed in a porous polymer matrix, with polymers such as vinyl chloride, vinyl chloride-propylene copolymer, and vinyl chloride-vinyl acetate copolymer; cloth, both naturally occurring (e.g., cotton) and synthetic (e.g., nylon or rayon); porous gels, such as silica gel, agarose, dextran, and gelatin; polymeric films, such as polyacrylamide; and
• the colorant may be applied to the solid support in the form of a composition that contains a mobile carrier.
• the carrier may be a liquid, gas, gel, etc., and may be selected to provide the desired performance (time for change of color, contrast between different areas, and sensitivity) of the colorant.
• the carrier may be an aqueous solvent, such as water, as well as a non-aqueous solvent, such as glycols (e.g., propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycols, ethoxydiglycol, and dipropyleneglycol); alcohols (e.g., methanol, ethanol, n-propanol, and isopropanol); triglycerides; ethyl acetate; acetone; triacetin; acetonitrile, tetrahydrafuran; xylenes; formaldehydes (e.g., dimethylformamide, "DMF"); etc.
• glycols e.g., propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycols, ethoxydiglycol, and dipropyleneglycol
• alcohols e.g.
• additives may also be incorporated into the array addresses, either separately or in conjunction with the colorant composition.
• cyclodextrins are employed that enhance the sensitivity of the colorant and the contrast between individual array addresses. While not wishing to be bound by theory, the present inventors believe that such additives may inhibit the crystallization of the colorant and thus provide a more vivid color and also enhance detection sensitivity. That is, single colorant molecules have greater sensitivity for microorganisms because each colorant molecule is free to interact with the microbial membrane. In contrast, small crystals of colorant have to first dissolve and then penetrate the membrane.
• Suitable cyclodextrins may include, but are not limited to, hydroxypropyl- ⁇ -cyclodextrin, hydro xyethyl- ⁇ - cyclodextrin, ⁇ -cyclodextrin, hydroxypropyl- ⁇ -cyclodextrin, and hydroxyethyl- ⁇ - cyclodextrin, which are commercially available from Cerestar International of Hammond, Indiana.
• Surfactants may also help enhance the sensitivity of the colorant and the contrast between different addresses.
• Particularly desired surfactants are nonionic surfactants, such as ethoxylated alkylphenols, ethoxylated and propoxylated fatty alcohols, ethylene oxide-propylene oxide block copolymers, ethoxylated esters of fatty (Ca -de) acids, condensation products of ethylene oxide with long chain amines or amides, condensation products of ethylene oxide with alcohols, acetylenic diols, and mixtures thereof.
• nonionic surfactants such as ethoxylated alkylphenols, ethoxylated and propoxylated fatty alcohols, ethylene oxide-propylene oxide block copolymers, ethoxylated esters of fatty (Ca -de) acids, condensation products of ethylene oxide with long chain amines or amides, condensation products of ethylene oxide with alcohols, acetylenic diols,
• nonionic surfactants include, but are not limited to, methyl gluceth-10, PEG-20 methyl glucose distearate, PEG-20 methyl glucose sesquistearate, Cn -I5 pareth- 20, ceteth-8, ceteth-12, dodoxynol-12, laureth-15, PEG-20 castor oil, polysorbate 20, steareth-20, polyoxyethylene-10 cetyl ether, polyoxyethylene-10 stearyl ether, polyoxyethylene-20 cetyl ether, polyoxyethylene-10 oleyl ether, polyoxyethylene-
• oleyl ether an ethoxylated nonylphenol, ethoxylated octylphenol, ethoxylated dodecylphenol, or ethoxylated fatty (C 6 -C 22 ) alcohol, including 3 to 20 ethylene oxide moieties, polyoxyethylene-20 isohexadecyl ether, polyoxyethylene-23 glycerol laurate, polyoxy-ethylene-20 glyceryl stearate, PPG-10 methyl glucose ether, PPG-20 methyl glucose ether, polyoxyethylene-20 sorbitan monoesters, polyoxyethylene-80 castor oil, polyoxyethylene-15 tridecyl ether, polyoxy-ethylene- 6 tridecyl ether, laureth-2, laureth-3, laureth-4, PEG-3 castor oil, PEG 600 dioleate, PEG 400 dioleate, and mixtures thereof.
• nonionic surfactants may include the SURFYNOL® range of acet
• TWEEN® range of polyoxyethylene surfactants available from Fischer Scientific of Pittsburgh, Pennsylvania.
• a binder may also be employed to facilitate the immobilization of the colorant on the solid support.
• water-soluble organic polymers may be employed as binders, such as polysaccharides and derivatives thereof.
• Polysaccharides are polymers containing repeated carbohydrate units, which may be cationic, anionic, nonionic, and/or amphoteric.
• the polysaccharide is a nonionic, cationic, anionic, and/or amphoteric cellulosic ether.
• Suitable nonionic cellulosic ethers may include, but are not limited to, alkyl cellulose ethers, such as methyl cellulose and ethyl cellulose; hydroxyalkyl cellulose ethers, such as hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl hydroxybutyl cellulose, hydroxyethyl hydroxypropyl cellulose, hydroxyethyl hydroxybutyl cellulose and hydroxyethyl hydroxypropyl hydroxybutyl cellulose; alkyl hydroxyalkyl cellulose ethers, such as methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, ethyl hydroxypropyl cellulose, methyl ethyl hydroxyethyl cellulose and methyl ethyl hydroxypropyl cellulose; and so forth.
• alkyl cellulose ethers such as methyl cellulose and e
• Suitable techniques for applying the colorant composition to the solid support in the form of individual array addresses include printing, dipping, spraying, melt extruding, coating (e.g., solvent coating, powder coating, brush coating, etc.), spraying, and so forth.
• Printing techniques may include, for instance, gravure printing, flexographic printing, screen printing, laser printing, thermal ribbon printing, piston printing, etc.
• ink-jet printing techniques are employed to form the array on the support. Ink-jet printing is a non-contact printing technique that involves forcing an ink through a tiny nozzle (or a series of nozzles) to form droplets that are directed toward the support.
• DOD Drop-On-Demand
• continuous ink-jet printing Two techniques are generally utilized, i.e., "DOD" (Drop-On-Demand) or “continuous” ink-jet printing.
• DOD systems use a pressurization actuator at each orifice to break the ink into droplets.
• the pressurization actuator in each system may be a piezoelectric crystal, an acoustic device, a thermal device, etc.
• the selection of the type of ink jet system varies on the type of material to be printed from the print head. For example, conductive materials are sometimes required for continuous systems because the droplets are deflected electrostatically. Thus, when the sample channel is formed from a dielectric material, DOD printing techniques may be more desirable.
• the colorant composition may be formed as a printing ink using any of a variety of known components and/or methods.
• the printing ink may contain water as a carrier, and particularly deionized water.
• Various co-carriers may also be included in the ink, such as lactam, N-methyl pyrrolidone, N- methylacetamide, N-methylmorpholine-N-oxide, N,N-dimethylacetamide, N-methyl formamide, propyleneglycol-monomethylether, tetramethylene sulfone, tripropyleneglycolmonomethylether, propylene glycol, and triethanolamine (TEA).
• Humectants may also be utilized, such as ethylene glycol; diethylene glycol; glycerine; polyethylene glycol 200, 300, 400, and 600; propane 1 ,3 diol; propylene- glycolmonomethyl ethers, such as Dowanol PM (Gallade Chemical Inc., Santa Ana, CA); polyhydric alcohols; or combinations thereof.
• Other additives may also be included to improve ink performance, such as a chelating agent to sequester metal ions that could become involved in chemical reactions over time, a corrosion inhibitor to help protect metal components of the printer or ink delivery system, and a surfactant to adjust the ink surface tension.
• the exact quantity of a colorant employed within an array address may vary based on a variety of factors, including the sensitivity of the colorant, the presence of other additives, the desired degree of detectability (e.g., with an unaided eye), the suspected concentration of the microorganism, etc. In some cases, it is desirable to only detect the presence of microorganisms at concentrations that are certain threshold concentrations (e.g., pathogenic).
• a concentration of about 1 x 10 3 colony forming units ("CFU") per milliliter of a test sample or more, in some embodiments about 1 x 10 5 CFU/ml or more, in some embodiments about 1 x 10 6 CFU/ml or more, and in some embodiments, about 1 x 10 7 CFU/ml or more of a microorganism may be detected in the present invention.
• colorants may be employed in an amount sufficient to undergo a detectable color change in the presence of a microorganism at a concentration of at least about 1 x 10 3 CFU per milliliter of the test sample.
• the colorant may be applied at a concentration from about 0.1 to about 100 milligrams per milliliter of carrier, in some embodiments from about 0.5 to about 60 milligrams per milliliter of carrier, and in some embodiments, from about 1 to about 40 milligrams per milliliter of carrier.
• the spectral response of the array of the present invention provides information regarding the presence of a microorganism to which it is exposed. If desired, the response of a reacted array may be compared (e.g., visually or with the aid of an instrument) to a control array, which is formed in a manner that is the same or similar to the test array with respect to its responsiveness to microorganisms.
• control arrays may likewise be employed that correspond to different types of microorganisms at a certain concentration.
• the microorganism may be identified by selecting the control array having a spectral response that is the same or substantially similar to the response of the reacted test array, and then correlating the selected control array to a particular microorganisms or class of microorganisms.
• the array itself may contain one or more colorants that do not generally undergo a detectable color change in the presence of the microorganism so that the colorant(s) may be used for comparative or control purposes.
• the spectral response of the array may be determined either visually or using instrumentation.
• color intensity is measured with an optical reader.
• the actual configuration and structure of the optical reader may generally vary as is readily understood by those skilled in the art.
• the optical reader contains an illumination source that is capable of emitting electromagnetic radiation and a detector that is capable of registering a signal
• the illumination source may be any device known in the art that is capable of providing electromagnetic radiation, such as light in the visible or near-visible range (e.g., infrared or ultraviolet light).
• suitable illumination sources include, but are not limited to, light emitting diodes (LED), flashlamps, cold-cathode fluorescent lamps, electroluminescent lamps, and so forth.
• the illumination may be multiplexed and/or collimated. In some cases, the illumination may be pulsed to reduce any background interference.
• illumination may be continuous or may combine continuous wave (CW) and pulsed illumination where multiple illumination beams are multiplexed (e.g., a pulsed beam is multiplexed with a CW beam), permitting signal discrimination between a signal induced by the CW source and a signal induced by the pulsed source.
• LEDs e.g., aluminum gallium arsenide red diodes, gallium phosphide green diodes, gallium arsenide phosphide green diodes, or indium gallium nitride violet/blue/ultraviolet (UV) diodes
• UV ultraviolet
• UV LED excitation diode suitable for use in the present invention is Model NSHU55OE (Nichia Corporation), which emits 750 to 1000 microwatts of optical power at a forward current of 10 milliamps (3.5-3.9 volts) into a beam with a full-width at half maximum of 10 degrees, a peak wavelength of 370-375 nanometers, and a spectral half-width of 12 nanometers.
• the illumination source may provide diffuse illumination to the colorant.
• an array of multiple point light sources e.g., LEDs
• Another particularly desired illumination source that is capable of providing diffuse illumination in a relatively inexpensive manner is an electroluminescent (EL) device.
• An EL device is generally a capacitor structure that utilizes a luminescent material (e.g., phosphor particles) sandwiched between electrodes, at least one of which is transparent to allow light to escape. Application of a voltage across the electrodes generates a changing electric field within the luminescent material that causes it to emit light.
• the detector may generally be any device known in the art that is capable of sensing a signal.
• the detector may be an electronic imaging detector that is configured for spatial discrimination.
• electronic imaging sensors include high speed, linear charge-coupled devices (CCD), charge-injection devices (CID), complementary-metal-oxide-semiconductor (CMOS) devices, and so forth.
• CCD linear charge-coupled devices
• CID charge-injection devices
• CMOS complementary-metal-oxide-semiconductor
• image detectors for instance, are generally two-dimensional arrays of electronic light sensors, although linear imaging detectors (e.g., linear CCD detectors) that include a single line of detector pixels or light sensors, such as, for example, those used for scanning images, may also be used.
• Each array includes a set of known, unique positions that may be referred to as "addresses.”
• Each address in an image detector is occupied by a sensor that covers an area (e.g., an area typically shaped as a box or a rectangle). This area is generally referred to as a "pixel" or pixel area.
• a detector pixel for instance, may be a CCD, CID, or a CMOS sensor, or any other device or sensor that detects or measures light.
• the size of detector pixels may vary widely, and may in some cases have a diameter or length as low as 0.2 micrometers.
• the detector may be a light sensor that lacks spatial discrimination capabilities.
• examples of such light sensors may include photomultiplier devices, photodiodes, such as avalanche photodiodes or silicon photodiodes, and so forth.
• Silicon photodiodes are sometimes advantageous in that they are inexpensive, sensitive, capable of high-speed operation (short risetime / high bandwidth), and easily integrated into most other semiconductor technology and monolithic circuitry.
• silicon photodiodes are physically small, which enables them to be readily incorporated into various types of detection systems. If silicon photodiodes are used, then the wavelength range of the emitted signal may be within their range of sensitivity, which is 400 to 1100 nanometers.
• Optical readers may generally employ any known detection technique, including, for instance, luminescence (e.g., fluorescence, phosphorescence, etc.), absorbance (e.g., fluorescent or non-fluorescent), diffraction, etc.
• the optical reader measures color intensity as a function of absorbance.
• absorbance readings are measured using a microplate reader from Dynex Technologies of Chantilly, Virginia (Model # MRX).
• absorbance readings are measured using a conventional test known as "CIELAB", which is discussed in Pocket Guide to
• CIELAB color space is somewhat visually uniform, a single number may be calculated that represents the difference between two colors as perceived by a human. This difference is termed ⁇ E and calculated by taking the square root of the sum of the squares of the three differences ( ⁇ L * , ⁇ a * , and ⁇ b * ) between the two colors.
• ⁇ E the difference between two colors as perceived by a human.
• each ⁇ E unit is approximately equal to a "just noticeable" difference between two colors.
• CIELAB is therefore a good measure for an objective device-independent color specification system that may be used as a reference color space for the purpose of color management and expression of changes in color.
• color intensities (L * , a * , and b * ) may thus be measured using, for instance, a handheld spectrophotometer from Minolta Co. Ltd. of Osaka, Japan (Model # CM2600d).
• This instrument utilizes the D/8 geometry conforming to CIE No.15, ISO 7724/1 , ASTME1164 and JIS Z8722- 1982 (diffused illumination/ 8-degree viewing system.
• the D65 light reflected by the specimen surface at an angle of 8 degrees to the normal of the surface is received by the specimen-measuring optical system.
• Still another suitable optical reader is the reflectance spectrophotometer described in U.S. Patent App. Pub. No. 2003/0119202 to Kaylor, et al., which is incorporated herein in its entirety by reference thereto for all purposes.
• transmission-mode detection systems may also be used in the present invention.
• microorganism contamination may be detected through the use of a array that produces a distinct spectral response for a microorganism or class or microorganisms.
• the microorganisms that may be detected in accordance with the present invention are not particularly limited, and may include bacteria, yeast, fungi, mold, protozoa, viruses, etc.
• Several relevant bacterial groups that may be detected in the present invention include, for instance, gram negative rods (e.g., Entereobacteria); gram negative curved rods (e.g., vibious, Heliobacter, Campylobacter, etc.); gram negative cocci (e.g., Neisseria); gram positive rods
• bacteria e.g., Bacillus, Clostridium, etc.
• gram positive cocci e.g., Staphylococcus, Streptococcus, etc.
• obligate intracellular parasites e.g.. Ricckettsia and Chlamydia
• acid fast rods e.g., Myobacterium, Nocardia, etc.
• spirochetes e.g., Treponema, Borellia, etc.
• mycoplasmas i.e., tiny bacteria that lack a cell wall.
• Particularly relevant bacteria include E.
• coli gram negative rod
• Klebsiella pneumonia gram negative rod
• Streptococcus gram positive cocci
• Salmonella choleraesuis gram negative rod
• Staphyloccus aureus gram positive cocci
• P. aeruginosa gram negative rod
• other microorganisms of interest include molds and yeasts (e.g., Candida albicans), which belong to the Fungi kingdom.
• Zygomycota for example, is a class of fungi that includes black bread mold and other molds that exhibit a symbiotic relationship with plants and animals.
• Ascomycota is another class of fungi, which includes yeasts, powdery mildews, black and blue-green molds, and some species that cause diseases such as Dutch elm disease, apple scab, and ergot. The life cycle of these fungi combines both sexual and asexual reproduction, and the hyphae are subdivided into porous walls that allow for passage of the nuclei and cytoplasm.
• Deuteromycota is another class of fungi that includes a miscellaneous collection of fungi that do not fit easily into the aforementioned classes or the Basidiomycota class (which includes most mushrooms, pore fungi, and puffball fungi).
• Deuteromycetes include the species that create cheese and penicillin, but also includes disease-causing members such as those that lead to athlete's foot and ringworm.
• the spectral response of the array of the present invention is rapid and may be detected within a relatively short period of time.
• the spectral response may occur in about 20 minutes or less, in some embodiments about 10 minutes or less, in some embodiments about 5 minutes or less, in some embodiments about 3 minutes or less, and in some embodiments, from about 10 seconds to about 2 minutes.
• the array may provide a "real-time" indication of the presence or absence of a microorganism or class of microorganisms.
• Escherichia coll ATCC #8739 (E coli)
• Psuedomonas aeruginosa ATCC #9027 (P aeruginosa)
• Klebsiella pneumoniae (ATCC #4352) (K pneumoniae) Proteus mirabilis (ATCC #7002) (P mirabilis) Haemophilus influenzae (ATCC #49247) (H influenzae) Moraxella lacunata (ATCC #17972) (M lacunata)
• Staphylococcus aureus (ATCC #6538) (S aureus) Lactobacillus acidophilus (ATCC #1197 ' 5) (L acidophilus) Staphylococcus epidermidis (ATCC #12228) (S epidermidis) Bacillus subtilis (ATCC #19659) (B subtilis) Enterococcus faecalis (ATCC #29212) (E faecalis) Streptococcus pyogenes (ATCC #10782) (S pyogenes) Streptococcus pneumoniae (ATCC #10015) (S pneumoniae)
• Candida albicans ATCC #10231 (C albicans) (C albicans)
• Aureobasidium pullulans (ATCC #16622) (A pullulans) Penicillium janthinellum (ATCC #10069) (P janthmellum)
• the colorants were dissolved in dimethylformamide (DMF).
• the colorant solutions were then pipetted onto 15-cm filter paper (available from VWR International - Catalog No. 28306-153) and allowed to dry.
• the filter paper was sectioned into quadrants to test four (4) samples - i.e., S. aureus, E. coli, C. albicans, and sterile water.
• 100 microliters of 10 7 CFU/mL of S. aureus was pipetted onto the filter paper in one quadrant, 100 microliters of 10 7 CFU/mL of E. coli was pipetted onto the filter paper in a second quadrant, 100 microliters of 10 6 CFU/mL of C.
• albicans was pipetted onto the filter paper in a third quadrant, and sterile water was pipetted in the final quadrant. Color changes in the colorants were observed and recorded for each of the samples tested. The color was recorded immediately after the color change to inhibit the fading (or loss of intensity) of the colors as the samples dried. Table 2 presents the observations from the experiment.
• the gram-negative microorganisms tested were £. coli, P. aeruginosa, K. pneumoniae, and P. mirabilis.
• the colorant samples were prepared in a manner similar to Example 1. Unless otherwise specified, the colorants were dissolved in dimethylformamide (DMF). Each of the colorant solutions were pipetted onto two separate pieces of VWR filter paper and allowed to dry. One filter paper sample with the dried colorant was sectioned into five approximately equal sections to test the five gram- positive microorganisms. The other filter paper sample was sectioned into quadrants to test the four gram negative microorganisms. 100 microliters of 10 7 CFU/mL of each microorganism sample was pipetted into their respective section of the sample of filter paper. Table 5 presents the observations from the gram positive microorganisms and Table 6 presents the observations from the gram negative microorganisms.
• DMF dimethylformamide
• the ability to rapidly detect upper respiratory pathogens utilizing a group of colorants was demonstrated.
• the colorants tested were Alizarin Red S, Universal Indicator 3-10, Nile Red, Plasmocorinth B, Iron III Porphyrin, Eriochrome Blue Black B, Chrome Azurol S, Orcein, Alizarin Complexone, Phenol Red, Carminic Acid, Methyl Orange, and TMPD.
• the upper respiratory infection pathogens tested were H. influenzae, M. lacunata, S. pyogenes, S. pneumoniae, A. pullulans, and P. janthinellum.
• the colorant samples were prepared in a manner similar to Example 1. Unless otherwise specified, the colorants were dissolved in dimethylformamide (DMF). Color changes in the colorants were observed and recorded for each of the samples tested. Table 7 presents the observations from the upper respiratory infection pathogens.
• DMF dimethylformamide

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