Hemin/Au nanorods/self-doped TiO₂ nanowires as a novel photoelectrochemical bioanalysis platform

As a recently developed detection technique, photoelectrochemical (PEC) measurement has received extensive attention. However, owing to the lack of a comprehensive approach to engineer the photo-generated carriers, the performance is still limited. As an example, a significant use of PEC measurement might be in understanding the roles of glutathione in physiological and pathological processes. Here, we developed a new approach for engineering the photo-generated carriers with the aid of the synergic effect of self-doping, surface plasmon resonance, electrical field amplification effect, etc. Thus, a highly sensitive multicomponent PEC platform has been developed, in which Au nanorods are decorated on the surface of self-doped TiO₂ nanowires, followed by surface receptor functionalization with hemin for capturing glutathione. The synergic effect effectively increases generation, separation and transfer kinetics of the photo-generated carriers, which can be further increased by using a mixture of Au nanorods with different aspect ratios to tune the absorption wavelength to the entire UV-visible region. As a result, this system exhibits a broad linear range from 10 nM to 17.5 μM and low detection limit down to 8.6 nM for detecting glutathione, about 1-2 orders of magnitude lower than most existing PEC sensors.