High performance cholesterol sensor based on ZnO nanotubes grown on Si/Ag electrodes

Zinc oxide nanotube (ZNT) arrays were grown on Si/Ag substrate by one-step chemical process in an aqueous solution and further used as a working electrode to fabricate an enzyme-based cholesterol biosensor through immobilization of cholesterol oxidase (ChOx). The fabricated biosensors exhibit high and reproducible sensitivity of 79.40 μA/mM/cm2, wide linear range from 1.0 μM to 13.0 mM, fast response time of ~ 2 s and ultra-low detection limit of 0.5 nM (S/N = 3) for cholesterol sensing. The anti-interference ability and long-term stability of the biosensor were also assessed. Finally, the biosensor was applied to analyze cholesterol concentration in human serum samples.