A Chemical Redox Cycling-Based Dual-Mode Biosensor for Self-Powered Photoelectrochemical and Colorimetric Assay of Heat Shock Protein

To advance the biological understanding of heat shock protein (HSP) in different types of cancers, it is crucial to achieve its accurate determination. Herein, a dual-mode self-powered photoelectrochemical (PEC) and colorimetric platform was proposed by integrating enzymatic catalysis and a chemical redox cycling amplification strategy. In this system, ascorbic acid (AA), as the signal reporter for PEC and colorimetric assay, can be regenerated during the tris(2-carboxyethyl) phosphine-mediated chemical redox cycling process. For PEC detection, the reproduced electron donor AA could repeatedly combine with holes generated by the Bi₂S₃/Bi₂O₃ photoanode to effectively separate the photogenerated electron–hole. Besides, an AA-involved color reaction was evoked during the colorimetric assay to reduce colorless tris(bathophenanthroline) iron(III) to red tris(bathophenanthroline) iron(II). Owing to the ingenious signal amplification strategy, the developed dual-mode assay achieved the PEC and colorimetric determination of HSP90AA1 (one subtype of HSP family) in real samples. It is believed that this work will offer a new strategy to fabricate a dual-mode biosensor, which has great application prospects in the detection of various tumor biomarkers.