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

•Zinc oxide nanotubes synthesized by chemical process on Si/Ag substrate.•Cholesterol biosensor with immobilizing ChOx on the Si/Ag/ZNT electrode.•Fast response, high reproducibility and sensitivity with wide linear range.•The biosensor applied to analyze cholesterol concentration in serum samples.•A new platform for routine analysis of cholesterol in human blood samples.

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.