Sensor with improved shelf life

Abstract

The present invention provides a metal electrode stabilised by a coating, the coating comprising a sulfur containing moiety in its molecular structure. The coating may also include a hydrophilic group and a spacer between the sulfur containing moiety and the hydrophilic group. Preferably, the sulfur containing moiety is selected from the group comprising thiol, disulfide and SOx, and the hydrophilic group is selected from the group comprising hydroxyl, amine, carboxyl, carbonyl, oligo (ethylene oxide) chain, and zwitterionic species. Compounds useful in the present invention include 2-mercaptoethanol, 2-mercaptoethylamine, 3-mercaptopropionic acid, thiophene, 4-carboxythiophene, cysteine, homocysteine, and cystine.

1 . A coated metal electrode, comprising:
 a metal electrode; and   a coating layer disposed on at least one side of the metal electrode, the coating layer comprising a compound, the compound consisting of a sulphur-containing moiety, a hydrophilic group, and a spacer between the sulphur-containing moiety and the hydrophilic group,   wherein a temporal stability of the coated metal electrode is greater than a temporal stability of a corresponding uncoated metal electrode.   
     
     
         2 . The coated metal electrode of  claim 1 , wherein a fill speed of the coated metal electrode is less than a fill speed of a corresponding uncoated metal electrode. 
     
     
         3 . The coated metal electrode of  claim 1 , further comprising a surfactant layer over the coating layer. 
     
     
         4 . The coated metal electrode of  claim 1 , wherein the coating is selected from the group consisting of 2-mercaptoethanol, 2-mercaptoethylamine, 3-mercaptopropionic acid, thiophene, 3-carboxythiophene, L-cysteine, L-cystine, D-cysteine, D-cystine, L-homocysteine, and L-homocystine. 
     
     
         5 . The coated metal electrode of  claim 1 , wherein the coating is a stereospecific compound. 
     
     
         6 . The coated metal electrode of  claim 5 , wherein the stereospecific compound comprises a mixture of D isomers and L isomers of said compound. 
     
     
         7 . The coated metal electrode of  claim 5 , wherein the stereospecific compound comprises a D isomer. 
     
     
         8 . The coated metal electrode of  claim 5 , wherein the stereospecific compound comprises an L isomer. 
     
     
         9 . A method of preparing a metal electrode stabilized by a coating, the method comprising:
 providing a metal electrode;   contacting the metal electrode with a substance comprising a compound, the compound consisting of a sulfur-containing moiety and a hydrophilic group, whereby a coated metal electrode is obtained, the coated metal electrode having a temporal stability greater than a temporal stability of a corresponding uncoated metal electrode; and   applying a surfactant layer to the coated metal electrode.   
     
     
         10 . The method of  claim 9 , wherein the surfactant and substance are applied simultaneously. 
     
     
         11 . The method of  claim 9 , wherein the surfactant is applied to the electrode subsequent to the application of the substance. 
     
     
         12 . The method of  claim 9 , wherein a fill speed of the coated metal electrode is less than a fill speed of a corresponding uncoated metal electrode. 
     
     
         13 . A method of preparing a metal electrode stabilized by a coating, the method comprising:
 providing a metal electrode; and   contacting the metal electrode with a substance comprising a compound, the compound consisting of a sulfur-containing moiety, a hydrophilic group, and a spacer between the sulphur-containing moiety and the hydrophilic group, whereby a coated metal electrode is obtained, the coated metal electrode having a temporal stability greater than a temporal stability of a corresponding uncoated metal electrode.   
     
     
         14 . The method of  claim 13 , further comprising the step of overcoating the substance with a surfactant. 
     
     
         15 . The method of  claim 14 , wherein the surfactant and substance are applied simultaneously. 
     
     
         16 . The method of  claim 14 , wherein the surfactant is applied to the electrode subsequent to the application of the substance. 
     
     
         17 . The method of  claim 13 , wherein a fill speed of the coated metal electrode is less than a fill speed of a corresponding uncoated metal electrode. 
     
     
         18 . A method of sensing an analyte, the method comprising:
 contacting a sample comprising an analyte to a metal electrode, the metal electrode comprising a coating, the coating comprising a compound, the compound consisting of a sulphur-containing moiety, a hydrophilic group, and a spacer between the sulphur-containing moiety and the hydrophilic group, wherein a temporal stability of the coated metal electrode is greater than a temporal stability of a corresponding uncoated metal electrode; and   obtaining a measurement indicative of a presence of the analyte in the sample.   
     
     
         19 . The method of  claim 18 , wherein the coating further comprises a surfactant layer. 
     
     
         20 . The method of  claim 18 , wherein the coating is selected from the group consisting of 2-mercaptoethanol, 2-mercaptoethylamine, 3-mercaptopropionic acid, thiophene, 3-carboxythiophene, L-cysteine, L-cystine, D-cysteine, D-cystine, L-homocysteine, and L-homocystine. 
     
     
         21 . The method of  claim 18 , wherein the coating is a stereospecific compound. 
     
     
         22 . The method of  claim 19 , wherein the stereospecific compound comprises a mixture of D isomers and L isomers. 
     
     
         23 . The coated metal electrode according to  claim 19 , wherein the stereospecific compound comprises a D isomer. 
     
     
         24 . The coated metal electrode according to  claim 19 , wherein the stereospecific compound comprises an L isomer. 
     
     
         25 . The method of  claim 18 , wherein a fill speed of the coated metal electrode is less than a fill speed of a corresponding uncoated metal electrode.