Self-Powered Photoelectrochemical Aptasensor with a TiO₂/CdTe/PEDOT-Sensitized Photoanode and a RGO-Enhanced Sensing Cathode for Thrombin Detection

Self-powered photoelectrochemical (PEC) sensing platforms, which integrate a photoanode with a sensing cathode, have emerged as transformative strategies for analyzing biological samples due to their robust photocurrent responses and outstanding anti-interference capabilities. Building on this concept, a self-powered PEC aptasensor was designed to achieve the highly accurate and selective detection of thrombin (TB). The photoanode was constructed by sequentially modifying a bare indium tin oxide (ITO) electrode with titanium dioxide (TiO2) powder, aqueous cadmium telluride quantum dots (CdTe QDs), and poly(3,4-ethylenedioxythiophene) (PEDOT), resulting in a cosensitized TiO2/CdTe/PEDOT structure. The sensing cathode was prepared by electrodepositing reduced graphene oxide (RGO) onto an ITO substrate, followed by the immobilization of a TB-specific aptamer on the ITO/RGO surface. This spatial separation of the photoanode and cathode offers two key advantages: enhanced photoresponse and stable photocurrent compared to traditional cathodic PEC systems, as well as excellent sensitivity and selectivity with strong resistance to interference from reductive species and photoexcitation of the cathode. This self-powered PEC aptasensor demonstrates a highly reliable and efficient platform for target analyte detection, showcasing a superior performance and significant potential for diverse applications in biomolecular sensing.