Bioinduced Surface Oxygen Vacancies on Bismuth Trioxide Nanocrystals for Photocathodic Bioassays

Cathodic photoelectrochemistry withsuperior photostability andanti-interference capability has been shown to be appealing in thefield of bioanalysis. However, a major challenge regarding this technologyis the limited photoinduced electron transfer signal transductionmechanism. Herein, we disclose a finding of the bioinduced surfaceoxygen vacancy (V (O)) on bismuth trioxide(Bi2O3) nanocrystals, which underlies an innovativemechanism for cathodic photoelectrochemical (PEC) bioanalysis. Theprotocatechuic acid engendered from the tandem enzymatic reactionof p-hydroxybenzoate hydroxylase (PHBH) and glucose-6-phosphatedehydrogenase (G6PD) can coordinate with the surface of Bi2O3 nanocrystals through forming binary Bi-O-Cbonds, which breaks the initial Bi-O bonds and enables theescape of O2- from the lattice to form surface V (O) in situ. The surface V (O) can function as a separation center for chargecarriers, which is favorable to the generation of cathodic photocurrent.In such a system, the cathodic signal is linearly correlated withthe targets, glucose-6-phosphate (G-6-P) and G6PD, in concentrationranges of 8.0 to 8.0 x 10(5) & mu;M and 0.1 to 1.0x 10(4) U/L, achieving detection limits of 2.0 & mu;Mand 0.03 U/L, respectively. This study not only offers a way of introducingsurface V (O) in situ butalso enriches the current toolbox of cathodic PEC bioassays and promisesto stimulate further interest in exploring surface effect engineeringin other fields.