Development and surface characterization of a glucose biosensor based on a nanocolumnar ZnO film

Highlights: • Glucose biosensor based on self-assembled nanocolumnar ZnO deposited on stainless steel. • XPS applied to investigate the GOx immobilization on the ZnO nanocolumns surface. • Observable chemical shifts on O1s and Zn2p corroborates enzime immobilization. - Abstract: Highly oriented nanostructured ZnO films were grown on the surface of stainless steel plates (ZnO/SS) by chemical bath deposition (CBD). The films consisted of vertically aligned ZnO nanocolumns, ∼1 μm long and ∼80 nm wide, as observed by SEM (scanning electron microscopy) and FIB (focused ion beam). XRD (X-ray diffraction) confirmed the c-axis preferred orientation of the ZnO columns, which were functionalized with the glucose oxidase (GOx) enzyme into a biosensor of glucose. The electrochemical response studied by CV (cyclic voltammetry) proved that the biosensor was capable of detecting glucose from 1.5 up to 16 mM concentration range. XPS (X-ray photoelectron spectroscopy) analysis, excited with synchrotron radiation, probed the atom specific chemical environment at the electrode's surface and shed some light on the nature of the ZnO-GOx interaction.