Polyacrylamide-Based Redox Polymer for Connecting Redox Centers of Enzymes to Electrodes

Enzyme electrodes based on complexing a water-soluble copolymer of acrylamide and vinylimidazole with [Os(dmebpy)₂Cl]^+/2+ (dmebpy = 4, 4'-dimethyl-2, 2'-bipyridine) and cross-linking with oxidases by water-soluble cross-linkers are described. The potential of the polyacrylamide-based redox polymer is +55 mV (SCE), a typical electron diffusion coefficient (D_e) in the redox hydrogel that results from its cross-linking is (1.3 ± 0.1) × 10-9 cm²/s. The properties of the enzyme electrodes formed when this redox hydrogel “wired” horseradish peroxidase (HRP), lactate oxidase (LOx) or glucose oxidase (GOx) depended on the thickness of the hydrogel film, the chemistry of their cross-linking, and their enzyme content At the wired HRP electrodes, H₂O₂ was electrocatalytically reduced to water at 0.0 V (SCE). Lactate and glucose were electrocatalytically oxidized at 0.16 V (SCE). The GOx electrodes, when made with 140 μg/cm² thick polymer films, were selective for glucose in the presence of physiological concentrations of urate and ascorbate.