Nitric oxide biosensors based on the immobilization of hemoglobin on mesoporous titania electrodes

A nanocrystalline TiO2 film is an electrode material with large surface area which allows high levels of protein adsorption without loss of protein structure or activity. As an optically transparent semiconductor, titania can be used to carry out direct spectroelectrochemistry of proteins such as hemoglobin. We demonstrate that the high protein loading and the optical transparency and electrical conductivity of the Hb/TiO2 films allow the optical and/or electrochemical sensing of nitric oxide. In particular we demonstrate the nitric oxide cycle of oxyhemoglobin immobilized on TiO2 films and use it to electrochemically measure micromolar levels of nitric oxide.