Glutamate Biosensors Based on Electrical Communication Between L-Glutamate Oxidase and a Flexible Redox Polymer

Electrical communication between the flavin adenine dinucleotide redox centers of L-glutamate oxidase and a conventional carbon electrode has been achieved using a new electron transfer relay system based on a ferrocene-modified siloxane-ethylene oxide branch copolymer. Using cyclic voltammetry and stationary potential experiments, it was shown that spectrographic graphite electrodes modified with this redox polymer and L-glutamate oxidase respond rapidly to addition of glutamate, with steady-state current responses achieved in less than 1 min. At an applied potential of +400 mV (vs. Ag/AgCl), a lower detection limit of approximately 0.01 mM and an apparent Michaelis-Menten constant, KM app, of 0.20 mM were determined.