Sol–gel derived nanoporous cerium oxide film for application to cholesterol biosensor

Cholesterol oxidase (ChOx) has been immobilized onto sol–gel derived nano-structured cerium oxide (NS-CeO2) film deposited on indium-tin-oxide (ITO) coated glass substrate. Phase identification of sol–gel NS-CeO2 film carried out using X-ray diffraction (XRD) yields reflection peak at 29.4° corresponding to (1 1 1) plane with oriented crystallite (34 nm) along c-axis normal to the substrate. Electrochemical studies reveal that NS-CeO2 provides electroactive surface for the loading of ChOx and enhances electron transfer rate in the ChOx/NS-CeO2/ITO bioelectrode. The low value of Michaelis–Menten constant (Km) obtained as 2.08 mM indicates enhanced ChOx affinity to cholesterol. The observed results show application of sol–gel derived NS-CeO2 for biosensing without any functionalization.