Chemical cross-talk in flow-type integrated enzyme sensors

In flow-type integrated enzyme sensors, hydrogen peroxide produced at an upstream electrode is transported to downstream electrodes, and causes non-specific responses which are called as “chemical cross talks (CCTs)”. In this study, the relationship between CCTs and enzyme immobilization methods, namely an electrochemical pyrrole polymerization, a gelatin–glutaraldehyde crosslinking, and a photocrosslinkable prepolymer (PVA-SbQ) method, was investigated. The flow rate dependency and the substrate concentration dependency of CCTs were dependent on the enzyme immobilization methods. Therefore, the effects of the membrane permeability and enzyme density of bioselective layers on upstream and downstream electrodes, on CCT were investigated by using a gelatin–glutaraldehyde crosslinking method as an enzyme immobilization method. The CCTs correspond to the membrane permeability and enzyme density of a bioselective layer on an upstream electrode. Based on these results, an elimination method for CCT was proposed.