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

Abstract

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+ concentration increased in the range of 10 pM to 10 μM 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 environmental detection, biological analysis, and medical research.