Au nanoparticles-ZnO composite nanotubes using natural silk fibroin fiber as template for electrochemical non-enzymatic sensing of hydrogen peroxide

A novel electrochemical sensor based on the composite of gold nanoparticles/zinc oxide nanotube (AuNPs/ZnO-NTs) was constructed and its application as hydrogen peroxide (H₂O₂) non-enzymatic sensor was investigated. ZnO-NTs were prepared by a biomineralization strategy in which silk fibroin fiber (SFF) was used as template, and thus the ZnO-NTs inherited the advantages of SFF such as mechanical stability, flexible biomimetic morphology and biocompatibility. The AuNPs/ZnO-NTs was further prepared by the electrostatic absorption of AuNPs onto the surface of ZnO-NTs, and found to be capable to catalyze the reduction of H₂O₂. The working potential was 0.05 V, which was far higher than those in literatures, indicating the strong anti-interference ability in the real application. The catalytic current was linearly proportional in the concentration range of 1 μM–3.0 mM with a sensitivity of 1336.7 μA mM⁻¹ cm⁻². The detection limit was estimated to be 0.1 μM (S/N = 3). Such a high sensitivity was attributed to the electrocatalytic property of ZnO and high electron transfer ability of AuNPs/ZnO-NTs structure. Moreover, the final detection results of H₂O₂ in real samples showed the acceptable accuracy compared with the traditional potassium permanganate titration, exhibiting the prospect to be used as an applicable sensor in actual detections.