Studies on Glucose Biosensors Based on Nonmediated and Mediated Electrochemical Oxidation of Reduced Glucose Oxidase Encapsulated Within Organically Modified Sol-Gel Glasses

Abstract

A new, organically modified sol‐gel glass electrode is reported using 3‐aminopropyltriethoxy silane and 2‐(3,4‐epoxycyclohexyl)‐ethyltrimethoxy silane as sol‐gel precursors for the construction of electrochemical biosensors. Four different systems of new sol‐gel glass modified glucose electrodes are made in acidic medium having common sol‐gel precursors and: 1) glucose oxidase, 2) glucose oxidase along with polyethylene glycol, 3) glucose oxidase and graphite powder, and 4) glucose oxidase along with polyethylene glycol and graphite powder. Both nonmediated and mediated electrochemical regeneration of immobilized glucose oxidase within sol‐gel glasses are studied in these four systems. The nonmediated regeneration is achieved in the presence of oxygen as electron donor whereas mediated regeneration involves soluble ferrocene monocarboxylic acid as electron donor in each system. The electrochemical performance of sol‐gel glass based biosensors is compared on the basis of cyclic voltammetry and amperometry. This leads to the observations: i) all four systems reach a diffusion limited condition associated with the transport of soluble ferrocene monocarboxylic acid as well as for dissolved oxygen within the sol‐gel matrix, ii) the relative rate of diffusion of these analytes increases from system 1 to system 4, iii) both nonmediated and mediated amperometric responses at suitable potentials are based on the oxidation of H2O2 and enzymatically reduced soluble ferrocene with relatively amplified electrochemical signal of system 4. Data on the reduction of oxygen at conventional graphite disk electrode and at typical sol‐gel glass modified electrode are reported.

A Novel Ferrocene-Encapsulated Palladium-Linked Ormosil-Based Electrocatalytic Biosensor. The Role of the Reactive Functional Group

“…The electrode body used for the construction of ormosil modified electrode and subsequently the electrocatalytic glucose biosensor was the same as described in earlier publications [19,20].…”

“…There is great potential to study ferrocene encapsulated=linked sol-gel glasses for mediated biosensor applications. We recently reported on glucose biosensors [9,10,20] based on a sol-gel matrix of controlled porosity followed by an enzyme layer and subsequently above another layer of sol-gel glass of controlled porosity using 3-aminopropyltriethoxysilane and 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane as sol-gel glass precursors [9]. We studied both mediated and nonmediated response of glucose biosensor.…”

A Novel Ormosil Based Electrocatalytic Biosensor for Glucose/Ethanol Based on Dehydrogenase Modified Electrode

“…There is great potential to study ferrocene encapsulatedalinked sol-gel glasses for mediated biosensors applications. We have recently reported a glucose biosensor [19,20,30] based on a sol-gel matrix of controlled porosity followed by putting an enzyme layer and subsequently over that another layer of sol-gel glass of controlled porosity using 3-aminopropyltriethoxysilane and 2-(3,4-epoxycyclohexyl)-ethyltrimethoxy silane as sol-gel glass precursors [9]. We studied both mediated and nonmediated response of the glucose biosensor.…”

Library of electrocatalytic sites in nano-structured domains: Electrocatalysis of hydrogen peroxide

“…These contributions justify the necessity of nano-structured domain in electrocatalysis of hydrogen peroxide. We have studied in details on such systems encapsulating redox active moieties within ormosil network derived from 3-aminopropyltrimethoxysilane and 2-3-epoxycyclohexylpropyltrimethoxysilane (Pandey et al, 1999a(Pandey et al, , 1999b(Pandey et al, , 1999c(Pandey et al, , 2001a(Pandey et al, , 2001b(Pandey et al, , 2003a(Pandey et al, , 2003b(Pandey et al, , 2004a(Pandey et al, , 2004b(Pandey et al, , 2007Pandey and Upadhyay, 2005). Further introduction of 3-glycidoxypropyltrimethoxysilane into such matrix has an extra advantage for enhancing the material property in two different orientations; (i) structural densification, and (ii) possibility of introducing some novel electrocatalysts into nano-structured network.…”