Photoelectrochemical response to glutathione in Au-decorated ZnO nanorod array

Metal nanoparticle assisted photoelectrochemical (PEC) biosensing has attracted attention for point-of-care testing due to its fast and low background noise signal. However the interfacial charge transfer of plasmonic-enhanced biosensing is not yet fully understood. Herein, a plasmonic-enhanced PEC platform has been demonstrated for glutathione (GSH) detection based on a hybrid structure of a well-oriented zinc oxide nanorod array (ZnO NR) with gold nanoparticles (Au NPs) as photoanode. In the PEC system, the self-powered bioanalysis is carried out at 0 V versus Ag/AgCl under simulated sunlight. In detail, the optical experiments (e.g. photoluminescence, PL) and theoretical analysis (e.g. finite-difference time-domain, FDTD) illustrate the photoresponse enhancement mechanism of the Au NPs-ZnO NRs and reaction process of GSH. The GSH oxidization and the effect of pH on the photocurrent response are demonstrated and investigated. The as-prepared surface plasmon resonance (SPR) based PEC sensor could be considered for GSH detection for early diagnosis of tumors.