Signal “on-off” photoelectrochemical biosensor for gram-positive bacteria quick detection based on vancomycin functionalized BiVO4/Au photoelectrode

Abstract

Given the increasingly grave situation of bacterial infections and antibiotic resistance, there is an urgent demand for the development of rapid, straightforward, and highly sensitive techniques for bacterial detection and imaging. Here, a highly sensitive and label-free PEC biosensor was proposed for Gram-positive bacteria detection based on the vancomycin (Van) functionalized ITO/BiVO4/Au photoelectrode. The Gram-positive bacteria can be captured by the specific recognition of Van, which was immobilized AuNPs of the ITO/BiVO4/Au photoelectrode surface, thus enabling extreme acceleration of the detection procedure. Van not only acts as a sensitizer to increase the photocurrent but also acts as a probe molecule to specifically capture Gram-positive bacteria, achieving the signal “On-Off” response with minimized background noise. In addition, electrochemical impedance spectroscopy and scanning photoelectrochemical microscopy were used to illustrate the detection mechanism. The low detection limit of the new PEC biosensor was 15 colony forming units per milliliter (CFU/mL), and the detection range was 50–5 × 107 CFU/mL. Moreover, the PEC sensor had good stability and reproducibility, which was conducive to promoting further application and providing a foothold for ultrasensitive bacterial detection in food and environment.