Glucose oxidation by enzyme electrodes using genipin to crosslink chitosan, glucose oxidase and amine-containing osmium redox complexes

Genipin is used to simultaneously crosslink chitosan, amine-containing osmium redox complex and glucose oxidase on graphite disks to produce enzyme-based electrodes for glucose oxidation. The enzyme electrodes produce glucose oxidation current densities of 730 mu A cm(-2) in 50 mM phosphate buffered saline (150 mM NaCl, pH 7.4, 37 degrees C) containing 100 mM glucose at an applied potential of 0.45 V (vs. Ag/AgCl), higher than the 440 mu A cm(-2) for conventional poly(ethylene glycol) diglycidyl ether (PEGDGE) epoxy ring-opening cross-linked films. Addition of multiwalled carbon nanotubes results in current response as high as 4.9 +/- 0.3 mA cm(-2) in 100 mM glucose. The genipin cross-linked hydrogels deliver a 3 fold increase in stability for continuous amperometric current production over a 20 h period when compared to PEGDGE cross-linked hydrogels. Genipin provides an effective route for simultaneous crosslinking glucose oxidase, chitosan and the redox complex while further optimisation of the crosslinking process holds promise for application of the enzyme electrodes as fuel cell and sensor devices.