Use of microperoxidase-11 to functionalize tin dioxide electrodes for the optical and electrochemical sensing of hydrogen peroxide

In this paper, we employ microperoxidase MP-11 immobilized on mesoporous SnO2 electrodes in order to study its peroxidase activity and reaction mechanism. We demonstrate the catalytic redox chemistry of the immobilized MP-11 via direct interfacial electron transfer without the use of electron mediators. By taking advantage from the optical transparency of the SnO2 electrodes, optical absorbance spectroscopy is used in order to compliment the data information obtained from electrochemical techniques. The catalytic activity of the immobilized MP-11 is found to proceed via the Fenton reaction, yielding OH radical intermediates. We also demonstrate the viability of using this electrode system as a potential H2O2 biosensor with a sensitivity range of 0.05–30 μM.