Direct electron transfer of myoglobin in mesoporous silica KIT-6 modified on screen-printed electrode

A disposable hydrogen peroxide biosensor was developed based on the direct electron transfer of myoglobin (Mb) on mesopores KIT-6 modified screen-printed electrode (SPE) which was manually performed to fabricate the planar carbon electrodes. KIT-6 is a new material which can absorb abundant of Mb molecules. A mixture of Mb and KIT-6 was immobilized with nafion on electrode. The cyclic voltammetry experiment indicated that a pair of stable and well-defined reduction peaks with a formal potentials of −0.35, and −0.28 V versus saturated calomel electrode (SCE) was obtained, using the present modified electrode in phosphate buffer saline (0.05 M, pH 7.0) at scan rate of 100 mV s−1, characteristic of Mb heme Fe(III)/Fe(II) redox couple. The heterogeneous electron transfer rate constant ks was estimated to be 16.93 s−1. And the formal potential was pH-dependent, having two slopes of −54.7 and −49.3 mV/pH which illustrated one electron transfer. This modified electrode was applied to detect H2O2 with sensitivity of 55.68 mA M−1 cm−2. Infrared spectrum and UV–vis absorption spectra of immobilized Mb film were recorded. In conclusion, KIT-6 increases the electron transfer activity of Mb and this kind of H2O2 biosensor is low cost for using disposable.