A Chemical Redox\nCycling-Based Dual-Mode Biosensor\nfor Self-Powered Photoelectrochemical and Colorimetric Assay of Heat\nShock Protein

To advance the biological understanding of heat shock\nprotein (HSP)\nin different types of cancers, it is crucial to achieve its accurate\ndetermination. Herein, a dual-mode self-powered photoelectrochemical\n(PEC) and colorimetric platform was proposed by integrating enzymatic\ncatalysis and a chemical redox cycling amplification strategy. In\nthis system, ascorbic acid (AA), as the signal reporter for PEC and\ncolorimetric assay, can be regenerated during the tris(2-carboxyethyl)\nphosphine-mediated chemical redox cycling process. For PEC detection,\nthe reproduced electron donor AA could repeatedly combine with holes\ngenerated by the Bi<sub>2</sub>S<sub>3</sub>/Bi<sub>2</sub>O<sub>3</sub> photoanode to effectively separate the photogenerated electron–hole.\nBesides, an AA-involved color reaction was evoked during the colorimetric\nassay to reduce colorless tris(bathophenanthroline) iron(III) to red\ntris(bathophenanthroline) iron(II). Owing to the ingenious signal\namplification strategy, the developed dual-mode assay achieved the\nPEC and colorimetric determination of HSP90AA1 (one subtype of HSP\nfamily) in real samples. It is believed that this work will offer\na new strategy to fabricate a dual-mode biosensor, which has great\napplication prospects in the detection of various tumor biomarkers.