Bioinduced Surface Oxygen Vacancies on Bismuth Trioxide Nanocrystals for Photocathodic Bioassays

Cathodic photoelectrochemistry with superior photostability and anti-interference capability has been shown to be appealing in the field of bioanalysis. However, a major challenge regarding this technology is the limited photoinduced electron transfer signal transduction mechanism. Herein, we disclose a finding of the bioinduced surface oxygen vacancy ( V O ) on bismuth trioxide (Bi 2 O 3 ) nanocrystals, which underlies an innovative mechanism for cathodic photoelectrochemical (PEC) bioanalysis. The protocatechuic acid engendered from the tandem enzymatic reaction of p -hydroxybenzoate hydroxylase (PHBH) and glucose-6-phosphate dehydrogenase (G6PD) can coordinate with the surface of Bi 2 O 3 nanocrystals through forming binary Bi–O–C bonds, which breaks the initial Bi–O bonds and enables the escape of O 2– from the lattice to form surface V O in situ . The surface V O can function as a separation center for charge carriers, which is favorable to the generation of cathodic photocurrent. In such a system, the cathodic signal is linearly correlated with the targets, glucose-6-phosphate (G-6-P) and G6PD, in concentration ranges of 8.0 to 8.0 × 10 5 μM and 0.1 to 1.0 × 10 4 U/L, achieving detection limits of 2.0 μM and 0.03 U/L, respectively. This study not only offers a way of introducing surface V O in situ but also enriches the current toolbox of cathodic PEC bioassays and promises to stimulate further interest in exploring surface effect engineering in other fields.