Enhanced biosensing platform constructed using urchin-like ZnO-Au@CdS microspheres based on the combination of photoelectrochemical and bioetching strategies

Recently, photoelectrochemical (PEC) biosensing has received considerable attention with wide applications in biotechnology and biomedicine. Here we report a novel PEC biosensing platform constructed via the combined strategy of both PEC analysis and bioetching. Urchin-like ZnO-Au@CdS microspheres were obtained by depositing Au nanoparticles (NPs) and CdS NPs on the surface of urchin-like ZnO microspheres. The introduction of intermediate electrotransfer of Au NPs to isolated ZnO and CdS systems significantly enhances the PEC property. CdS NPs can be irreversibly bioetched by an enzymatic reaction catalyzed by horseradish peroxidase (HRP) and H2O2. As a result, H2O2 detection is realized based on the decrease of the intensity of the PEC signal. This mediator-free and interference-free sensing platform has a linear range from 0.15 to 100 μM with a detection limit of 0.04 μM H2O2 at S/N = 3. Furthermore, glucose oxidase (GOD) was successfully immobilized on ZnO-Au@CdS microspheres to construct a glucose biosensor with a detection limit of 0.18 μM at S/N = 3. The PEC biosensor shows good sensing performance with low detection limit, mediator-free and accuracy, strong anti-interference, promising its application in PEC biosensing.