Glucose microbiosensor based on MnO2 and glucose oxidase modified carbon fiber microelectrode

A glucose microbiosensor has been developed using electrochemical codeposition of glucose oxidase (GOx) along with MnO2 as mediator, onto a single carbon fiber microelectrode. A two-step deposition of only MnO2 initially and then of MnO2 in the presence of GOx has been introduced to ensure appropriate activity of the mediator. Several parameters such as deposition potential and time, concentration levels etc. have been characterized and optimized. A thin Nation film was applied as an immobilization/encapsulation and interference-free protective layer. The proposed microbiosensor was employed as an amperometric glucose detector at pH 7.5 at an operating potential of +0.58 V (vs. Ag/AgCl). The microbiosensor is characterized by a well-reproducible amperometric response, linear signal-to-glucose concentration range from 1.5 mmol L-1 to 45 mmol L-1, and a limit of detection (S/N = 3) of 0.8 mmol L-1. The microbiosensor exhibits good stability over more than ten hours of continuous measurement.