Dependence of catalytic activity and long-term stability of enzyme hydrogel films on curing time

Enzyme hydrogels were prepared on carbon film electrodes using glucose oxidase and an epoxide crosslinking agent. The catalytic activity of the gels was found to depend strongly on curing time. The competing effects of increased mechanical stability and decreased enzyme activity as curing time increases resulted in the highest catalytic activity for films cured for 24h at 25 degrees C. Weekly electrochemical measurements established that the long-term stabilities of all hydrogels cured for 24-72 h were similar, with close to half of the initial catalytic activity being retained after immersion for 3 months in agitated phosphate buffer solution at 25 degrees C.