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
  • C12Q1/001—Enzyme electrodes
  • C12Q1/002—Electrode membranes
• • 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
  • C12Q1/001—Enzyme electrodes
  • C12Q1/005—Enzyme electrodes involving specific analytes or enzymes
  • C12Q1/006—Enzyme electrodes involving specific analytes or enzymes for glucose

Definitions

• the present invention relates in general to a diffusion-limiting hydrogel membrane system for use in analyte detection systems. More specifically, the present invention relates to cast analyte diffusion-limiting hydrogel membranes for filtering an analyte from fluids, comprising a water soluble photopolymerizable hydrophilic hydrogel monomer, capable of limiting the amount of analyte that will react with an analyte responsive enzyme and thus, further enabling a detection device to operate on a discrete basis or continually over an extended period of time.
• the present invention provides a diffusion-limiting hydrogel membrane system for filtering analytes or other desired characteristics from a fluid.
• the hydrogel membrane system can be employed in a detection device wherein the diffusion-limiting hydrogel membrane operates to regulate the amount of analyte that is present at the sensor electrodes at any given time, thus, allowing the sensor electrodes to operate on a discrete basis or continuously over longer periods of time without substantially depleting the amount of reactant present on the sensor electrodes.
• Figure 1A illustrates a cross sectional view of an assay device containing one embodiment of a cast analyte diffusion limiting membrane according to the present invention.
• Figure IB illustrates a front view of an assay device containing one embodiment of a cast analyte diffusion limiting membrane according to the present invention.
• Figure 2 is a graph indicating the results of example 1.
• Figure 3 is a graph indicating the results of example 2.
• Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment comprises from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another embodiment.
• analyte shall mean the component that is being filtered from a liquid or gas and/or detected and/or measured in a detection device.
• the analyte can include without limitation, glucose, acetoacetate, ammonia, catecholamines, creatine, creatinine, fructose, galactose, ⁇ -hydroxybutyric acid, bilirubin, lactate, lactic acid, amino acids, urea, uric acid, salicylates, pH, magnesium, calcium, lithium, lead, potassium, sodium, chloride, iron, and any other electrolyte, vitamin, protein, nutrient, pharmaceutical compounds, or other such characteristic desired.
• electrolyte means a chemical compound that ionizes when dissolved to produce an electrically conductive medium.
• fluid means a liquid or a gas.
• biological fluid means blood serum, whole blood, interstitial fluid, lymph fluid, spinal fluid, plasma or any combinations of these fluids. "Interstitial fluid” further refers to the clear fluid that occupies the space between the cells in the body.
• biological membrane means the outer layer of an organism, such as skin or mucous membrane, the structure separating one area of an organism from another, such as a capillary wall, or the outer layer of an organism which separates the organism from its external environment, such as skin, buccal mucosa or other mucous membrane.
• hydrogel means a polymeric material that can absorb 20% or more of its weight in water while simultaneously maintaining a distinct three- dimensional structure. More specifically, the hydrogels according to the present invention can be comprised of an aerogel that dries without significant collapse of the macroscopic structure and which absorbs water into macropores without substantial macroscopic swelling or, alternatively, xerogels which absorb water by swelling. It is further envisioned by the present invention that suitable hydrogels can include dry polymers that will swell in aqueous environments.
• suitable hydrogels for use in the present invention include without limitation 2-hydroxyethyl methacrylate, N,N,-dimethacrylamide, N-vinylpyrrolidine, polyethyleneglycol dimethacrylate, and/or copolymers thereof.
• the term "cast” means a method of forming a coating over an electrode area. Representative examples can include doctor blading, spraying, and/or dipping.
• diffusion-limiting hydrogel membrane means a hydrogel that limits the flow of analytes from one space to another.
• the term “detection device” means any assay device suitable for measuring a desired characteristic of a fluid on a continual or discrete basis.
• An example of such device is that disclosed by International Patent Application No. PCT/US00/09393 which application is incorporated herein by this reference in its entirety.
• the term “sensor electrode” means an electrode suitable for detecting the concentration of various ions in an aqueous and/or gaseous environment. Examples of suitable sensor electrodes according to the present invention include without limitation platinumized carbon ink or platinum metal held at a given electrical potential to cause the reduction of an analyte.
• the present invention shows a cross-sectional view of a detection device 10 which operates on a continuous basis.
• the device 10 contains an inlet port 40 to receive fluid and a chamber 50 in fluid communication with the inlet port 40, and an outlet port 60 in fluid communication with the chamber 50, where the outlet port 60 is designed to allow the discharge of fluid.
• the chamber 50 further comprises a first working sensor electrode 12, a second working sensor electrode 14, a reference electrode 16 and a counter electrode 18.
• a first layer of an analyte responsive enzyme 20, such as glucose oxidase, is applied to at least one of the working sensor electrodes 12 or 14.
• a second layer comprising a composition comprising a diffusion-limiting hydrogel membrane 30 is applied to at least one of the working sensor electrodes 12 or 14, wherein the first layer is in direct contact with at least one sensor electrode and the second layer is in direct contact with the first layer.
• the device 10 of the present invention may further comprise an external channel 70, wherein one end of the external channel 70 is in fluid communication with the inlet port 40 and the other end is in fluid communication with at least one liquid and/or gas.
• the analyte responsive enzyme 20 and the composition comprising a diffusion-limiting hydrogel membrane are mixed together and applied to at least one of the working sensor electrodes 12 or 14 as a mono-layer membrane system.
• Figure IB is a front view of the detection device 10 and is described the same as figure 1 A above.
• the present invention provides a diffusion limiting membrane system for filtering an analyte from a liquid, comprising: a) a first layer comprising an analyte responsive enzyme; and b) a second layer comprising a water-soluble monomer composition, wherein the first layer is in direct contact with one or more sensor electrodes and the second layer is in direct contact with the first layer.
• a diffusion-limiting hydrogel membrane system for filtering glucose from fluids comprising a glucose limiting membrane comprising a composition comprising a water soluble monomer, an enzyme, and an initiator, wherein the composition is disposed on one or more sensor electrodes and cured in the presence of sunlight or UV light.
• the present invention further provides a diffusion-limiting hydrogel membrane system for filtering glucose from fluids comprising a composition comprising a water soluble monomer, a cross-linking agent, an enzyme, and an initiator, wherein the composition is disposed on one or more sensor electrodes and cured in the presence of sunlight or UV light.
• the present invention further provides a diffusion-limiting hydrogel membrane system comprising: a) a first layer comprising an analyte responsive enzyme; and b) a second layer comprising a water-soluble monomer composition, wherein the first layer is in direct contact with one or more sensor electrodes and the second layer is in direct contact with the first layer.
• the present invention provides a diffusion-limiting hydrogel membrane for filtering an analyte from a fluid, comprising: a) a first layer comprising an analyte responsive enzyme; and b) a second layer comprising a water-soluble monomer composition, wherein the first layer is in direct contact with one or more sensor electrodes and the second layer is in direct contact with the first layer.
• Suitable analytes for use with the present invention include without limitation glucose, acetoacetate, ammonia, catecholamines, creatine, creatinine, fructose, galactose, ⁇ -hydroxybutyric acid, bilirubin, lactate, lactic acid, amino acids, urea, uric acid, salicylates, pH, magnesium, calcium, lithium, lead, potassium, sodium, chloride, iron, and any other electrolyte, vitamin, protein, nutrient, pharmaceutical compounds, or other such characteristic desired.
• Suitable analyte responsive enzymes for use in the diffusion-limiting hydrogel membranes of the present invention will be dependent upon the desired use of the invention.
• the glucose responsive enzyme is glucose oxidase, which is available from Sigma.
• any appropriate enzyme recognized for use in detecting glucose could be employed.
• the analyte responsive enzyme is dissolved in deionized water or phosphate buffered de-ionized water.
• the phosphate buffer system acts to maintain the analyte responsive enzyme at a pH value within the range of normal physiological levels.
• the analyte responsive enzyme can be dissolved in an amount of from about Img/mL to about lOOmg/mL.
• the enzyme is dissolved in an amount of from about Img/mL to about 50mg/mL.
• the enzyme can be dissolved in an amount of from about Img/mL to about lOmg/mL.
• Suitable water soluble monomers for use in the present include 2-hydroxyethyl methacrylate, N,N,-dimethacrylamide, N-vinylpyrrolidine, polyethyleneglycol dimethacrylate, and/or copolymers thereof.
• the water- soluble monomers for use in the inventive membranes are highly water permeable hydrogels, such as 2-hydroxyethyl methacrylate (HEMA).
• HEMA 2-hydroxyethyl methacrylate
• the water soluble monomer of the present invention is diluted in an aqueous medium.
• the hydrogel monomers of the present invention can be diluted in the aqueous medium at a range of dilution from about 0.01% to about 50% by volume.
• the range of dilution is from about 0.05% to about 10% by volume.
• the range of dilution is from about 0.1% to about 5% by volume.
• the water soluble monomer of the present invention can further comprise one or more initiators.
• Any water soluble UV or thermal initiators known in the art can be used with the present invention.
• suitable initiators for use in the invention include 2,2 dimethoxy-2- phenylacetophenone, Vazo 52®, available from DuPont, and Vazo 64®, also available from DuPont.
• the initiator is introduced into the water soluble monomer in an amount of from about 1 to about 10% by weight. In another embodiment, the initiator is introduced into the water soluble monomer in an amount of from about 2 to about 5% by weight.
• the water soluble monomer of the present invention can be cast or cured directly onto an electrode in the presence of sunlight or ultraviolet light without requiring the use of an adhesive or special processing to further protect an enzyme within the system.
• the water soluble monomer composition further comprises water soluble cross-linking agents.
• the cross-linking agent can participate in the polymerization of the water soluble monomer and thus facilitate the formation of the desired hydrogel membrane.
• suitable cross- linking agents include without limitation polytheyleneglycol dimethacryalate and/or gluteraldehyde.
• any water soluble free radical cross-linking agents can be used in the present invention.
• the cross-linking agents can be introduced into the water soluble monomer in an amount of from about 1 to about 10% by volume.
• the cross-linking agent can be introduced into the water soluble monomer in an amount of from about 2 to about 5% by volume.
• the thickness of the membranes of the present invention is from about 2 to about 50 micrometers. In another embodiment, the thickness of the membrane is from about 2 to about 25 micrometers. In still a further embodiment, the thickness of the membrane is from about 2 to about 20 micrometers.
• Example 1 relates to a bi-layer diffusion-limiting hydrogel membrane system for filtering glucose from biological fluids.
• solution 1 was prepared, and consisted of 1000 ⁇ l of 2-hydroxyethyl methacrylate and 4% by weight of a UV initiator, 2,2 Dimethoxy-2-phenylacetophenone .
• a detection device 10 such as the one shown in figure 1 A, a 0.5 ⁇ l drop of solution 2, comprised of 495 ⁇ l of a phosphate buffer system (PBS), lO ⁇ l of gluteraldehyde, 4 mg of Glucose Oxidase, and 30 mg of bovine serum albumin (BSA), was placed on at least one of the working sensor electrodes 12 or 14.
• PBS phosphate buffer system
• BSA bovine serum albumin
• This drop was allowed to dry for 12hrs after which a l ⁇ l drop of solution 3, which contained 495 ⁇ l of PBS and lO ⁇ l of solution 1, was placed on top of the drop on the at least one working sensor electrode 12 or 14.
• This second drop was exposed to long wave U V radiation for 0.5 hrs, wherein the radiation value was approximately 415nm tc approximately 430nm.
• the cured hydrogel membrane was then placed in a solution of de-ionized water and PBS and tested against a series of glucose levels as seen in figure 2.
• the results for this bi-layer hydrogel membrane system are set forth in said figure 2, wherein it illustrates that the bi-layer diffusion limiting hydrogel membrane system of example 1 was suitable for accurately detecting glucose levels at concentrations of up to approximately 25 to 30mM.
• Example 2 relates to a single layer diffusion-limiting hydrogel membrane system for filtering glucose from biological fluids.
• solution 1 was prepared, and consisted of 1000 ⁇ l of 2-hydroxyethyl methacrylate and 4% by weight of 2,2 Dimethoxy-2-phenylacetophenone.
• a detection device 10 such as the one shown in figure 1A
• a 0.5 ⁇ l drop of solution 2 which contained 495 ⁇ l of PBS, 4 mg of Glucose Oxidase, and 10 ⁇ l of solution 1
• This 0.5 ⁇ l drop was exposed to long wave UV radiation for 0.5 hrs, wherein the radiation value was approximately 415nm to approximately 430nm.

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• 2001
  • 2001-02-01 WO PCT/US2001/003304 patent/WO2001057241A2/en not_active Application Discontinuation
  • 2001-02-01 CA CA002398810A patent/CA2398810A1/en not_active Abandoned
  • 2001-02-01 AU AU36612/01A patent/AU3661201A/en not_active Abandoned
  • 2001-02-01 BR BR0108042-3A patent/BR0108042A/pt not_active Application Discontinuation
  • 2001-02-01 JP JP2001555864A patent/JP2003521248A/ja active Pending
  • 2001-02-01 MX MXPA02007447A patent/MXPA02007447A/es unknown
  • 2001-02-01 EP EP01908778A patent/EP1252509A2/de not_active Withdrawn

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