Electrochemical hydrogen peroxide sensors fabricated using cytochrome c immobilized on macroelectrodes and ultramicroelectrodes

We report the design and fabrication of hydrogen peroxide (H2O2) sensors using heme proteins immobilized on macroelectrodes and ultramicroelectrodes (UMEs). In this sensor design, the heme centers are directly “wired” to the electrode via the use of an imidazole-terminated self-assembled monolayer. We have systematically evaluated the effect of electrode type and size on sensor performance. The limit of detection for H2O2 determined using a 10-μm gold UME is significantly lower than that obtained using a stationary macroelectrode. Our results also highlight the advantages of using UMEs for enzyme kinetics analysis; the Km determined using a 10-μm UME is similar to that obtained from a rotating disk electrode.