Enzyme stabilization in electrochemical sensors

Abstract

The present invention relates to a composition for forming an electrode, an electrochemical sensor comprising the same, and a method for determining an analyte using the electrochemical sensor.

1 - 17 . (canceled) 
     
     
         18 . A composition for forming an electrode, the composition comprising an electrically conductive component having an analyte-specific enzyme covalently attached thereto, wherein the composition further comprises at least one electrically nonconductive or semiconductive component stabilizing the analyte-specific enzyme by either reacting with the analyte-specific enzyme to form a complex or conjugate with the enzyme or by converting chemical substances causing decomposition of the enzyme. 
     
     
         19 . The composition according to  claim 18 , wherein the electrically conductive component is a H 2 O 2 -decomposition catalyst. 
     
     
         20 . The composition according to  claim 18 , wherein the electrically conductive component is selected from the group consisting of activated carbon, carbon black, graphite, carbonaceous nanotubes, palladium, platinum, and hydroxides of iron oxide. 
     
     
         21 . The composition according to  claim 20 , wherein the electrically conductive component is selected from the group consisting of graphite and carbonaceous nanotubes. 
     
     
         22 . The composition according to  claim 18 , wherein the enzyme is an oxidase. 
     
     
         23 . The composition according to  claim 22 , wherein the enzyme is a glucose oxidase. 
     
     
         24 . The composition according to  claim 18 , wherein the electrically nonconductive or semiconductive enzyme-stabilizing component is a H 2 O 2 -decomposition catalyst. 
     
     
         25 . The composition according to  claim 18 , wherein the electrically nonconductive or semiconductive enzyme-stabilizing component is selected from the group consisting of an H 2 O 2 -degrading metal oxide and an H 2 O 2 -degrading enzyme. 
     
     
         26 . The composition according to  claim 25 , wherein the component is Ag 2 O, Al 2 O 3  or an oxide of a metal of the 4th period of the periodic table. 
     
     
         27 . The composition according to  claim 25 , wherein the component is peroxidase or catalase. 
     
     
         28 . The composition according to  claim 26 , wherein the oxide of a metal of the 4th period of the periodic table is MnO 2 , Mn 3 O 4  or Mn 5 O 8 , CuO or ZnO. 
     
     
         29 . The composition according to  claim 18 , wherein the analyte-specific enzyme is covalently attached to the electrically nonconductive or semiconductive enzyme-stabilizing component. 
     
     
         30 . The composition according to  claim 18 , wherein the electrically conductive component and/or the electrically nonconductive or semiconductive enzyme-stabilizing component is provided in the form of nanoparticles. 
     
     
         31 . The composition according to  claim 18 , further comprising at least one binder selected from the group consisting of fluorinated hydrocarbons, polycarbonates, polyisoprene, polyurethanes, acrylic resins, polyvinyl resins and silicones. 
     
     
         32 . The composition according to  claim 18 , wherein the electrically conductive component and/or the electrically nonconductive or semiconductive enzyme-stabilizing component is homogeneously dispersed in the composition. 
     
     
         33 . The composition according to  claim 18 , wherein the enzyme has a residual activity of at least 90% after storing the composition for at least 4 weeks at a temperature of 4° C., based on the total activity of the enzyme before storage. 
     
     
         34 . The composition according to  claim 33 , wherein the enzyme has a residual activity of at least 90% after storing the composition for at least 28 weeks at a temperature of 4° C., based on the total activity of the enzyme before storage. 
     
     
         35 . An electrochemical sensor for determining an analyte, the sensor comprising at least one working electrode and at least one reference electrode, wherein the working electrode comprises the composition according to  claim 18 . 
     
     
         36 . The electrochemical sensor according to  claim 35 , wherein it comprises a biocompatible coating covering the working electrode and the reference electrode. 
     
     
         37 . The electrochemical sensor according to  claim 35  for determining an analyte in a body fluid. 
     
     
         38 . The electrochemical sensor according to  claim 35  for determining an analyte selected from the group consisting of malic acid, alcohol, ammonium, ascorbic acid, cholesterol, cysteine, glucose, glutathione, glycerol, urea, 3-hydroxybutyrate, lactic acid, 5′ nucleotidase, peptides, pyruvate, salicylate and triglycerides. 
     
     
         39 . The electrochemical sensor according to  claim 38  for determining glucose. 
     
     
         40 . A method for determining an analyte, comprising the steps:
 (a) contacting a sample containing the analyte with an electrochemical sensor according to  claim 35 , and   (b) determining the presence and/or the amount of the analyte.