Development of redox-mediated oxysilane sol-gel biosensors on carbon-film electrode substrates

Abstract

Three types of carbon-film electrodes, made from electrical resistors with 1.5-, 15-, and 140-ω nominal resistances, were used to develop redox-mediated sol-gel biosensors, and the results were compared with those from previously investigated 2-ω carbon-film electrodes. Two different redox mediators, copper hexa-cyanoferrate and poly(neutral red), were deposited onto the carbon-film electrodes, with the latter showing good electrochemical properties for electroanalytical applications, which were best on electrodes made from 15-ω carbon-film resistors. It was not possible to deposit mediator film on the carbon-film resistor electrodes of 140-ω nominal resistance. Glucose oxidase was immobilized on poly(-neutral red) modified electrodes with sol-gel encapsulation from a mixture of 3-glycidoxypropyltrime- thoxysilane and methyltrimethoxysilane precursors at a volume ratio of 2 : 1. The best sensor electrochemical properties and response to glucose in model solution were found with electrodes constructed from 15-ω resistors, although the stability under the same conditions was better in the biosensors constructed with 2-ω nominal re-sistance electrodes. © 2008 Wiley Periodicals, Inc.