Bioinduced Surface Oxygen Vacancies on Bismuth Trioxide Nanocrystals for Photocathodic Bioassays

Abstract

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 (VO) on bismuth trioxide (Bi2O3) 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 Bi2O3 nanocrystals through forming binary Bi–O–C bonds, which breaks the initial Bi–O bonds and enables the escape of O2– from the lattice to form surface VO in situ. The surface VO 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 × 105 μM and 0.1 to 1.0 × 104 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 VO 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.