Highly-sensitive cholesterol biosensor based on platinum–gold hybrid functionalized ZnO nanorods

A novel scheme for the fabrication of gold/platinum hybrid functionalized ZnO nanorods (Pt–Au@ZnONRs) and multiwalled carbon nanotubes (MWCNTs) modified electrode is presented and its application for cholesterol biosensor is investigated. Firstly, Pt–Au@ZnONRs was prepared by the method of chemical synthesis. Then, the Pt–Au@ZnONRs suspension was dropped on the MWCNTs modified glass carbon electrode, and followed with cholesterol oxidase (ChOx) immobilization by the adsorbing interaction between the nano-material and ChOx as well as the electrostatic interaction between ZnONRs and ChOx molecules. The combination of MWCNTs and Pt–Au@ZnONRs provided a favorable environment for ChOx and resulted in the enhanced analytical response of the biosensor. The resulted biosensor exhibited a linear response to cholesterol in the wide range of 0.1–759.3 μM with a low detection limit of 0.03 μM and a high sensitivity of 26.8 μA mM−1. The calculated apparent Michaelis constant K M a p p was 1.84 mM, indicating a high affinity between ChOx and cholesterol.