Photoelectrochemical biosensor with Au@PTCA Schottky junction and multiple sandwich structures for Hg2+sensitive detection

Herein, a novel photoelectrochemical (PEC) biosensor was built on the strength of gold nanoparticles@3,4,9,10-Perylene tetracarboxylic (Au@PTCA) Schottky junction and multiple sandwich structures caused by thymine-Hg2+-thymine (T-Hg2+-T) and base complementary pairing, realizing the highly sensitive detection of mercury ion (Hg2+). The proposed Au@PTCA Schottky junction was formed by using PTCA as carrier and Au NPs as signal enhancer, which could significantly improve photoelectric conversion efficiency, resulting in a strong initial PEC signal. The multiple sandwich structures possessed high steric hindrance effect, which could directly block external electron supply and light harvesting, giving rise to a significantly quenched PEC signal. In addition, the execution of the multiple sandwich structures could extinguish initial PEC signal produced by Au@PTCA Schottky junction, acquiring the comparison of various PEC signals, thereby fulfilling the quantitative detection of Hg2+. The experimental results showed that the PEC signal was gradually suppressed as the Hg2+ concen-tration increased in the range of 10 pM to 10 mu M and the detection limit was 3.33 pM under optimal conditions, giving the sensor the advantages of high selectivity and excellent stability. This study demonstrated a promising method for sensitive detection of Hg2+ and offered a valuable approach with potential applications in envi-ronmental detection, biological analysis, and medical research.