Thioredoxin Reductase-Mediated Reaction Evokes In Situ Surface Polarization Effect on BiOIO3: Toward a New Sensing Strategy for Cathodic Photoelectrochemistry

We have witnessed the fast progress of cathodic photoelectrochemistry over the past decades, though its signal transduction tactic still lacks diversity. Exploring new sensing strategies for cathodic photoelectrochemistry is extremely demanding yet hugely challenging. This article puts forward a unique idea to incorporate an enzymatic reaction-invoked surface polarization effect (SPE) on the surface of BiOIO₃ to implement an innovative cathodic photoelectrochemical (PEC) bioanalysis. Specifically, the thioredoxin reductase (TrxR)-mediated reaction produced the polar glutathione (GSH), which spontaneously coordinated to the surface of BiOIO₃ and induced SPE by forming a polarized electric field, resulting in improved electron (e^-) and hole (h⁺) pair separation efficiency and an enhanced photocurrent output. Correlating this phenomenon with the detection of TrxR exhibited a high performance in terms of sensitivity and selectivity, achieving a linear range of 0.007-0.5 μM and a low detection limit of 2.0 nM (S/N = 3). This study brings refreshing inspiration for the cathodic PEC signal transduction tactic through enzyme-mediated in situ reaction to introduce SPE, which enriches the diversity of available signaling molecules. Moreover, this study unveils the potential of in situ generated SPE for extended and futuristic applications.