In this work, a specific and sensitive photoelectrochemical (PEC) biosensor has been constructed for the lead ion (Pb²⁺) assay by applying a silver nanoparticles@3,4,9,10-perylene tetracarboxylic acid (Ag@PTCA) Schottky junction as the signal substrate and cobalt tetraphenyl porphyrin (CoPP) as the signal quencher integrated with nucleic acid double-amplification strategies. The strong unidirectional conductivity of the Shottky junction and the surface plasmon resonance (SPR) effect of Ag NPs significantly enhanced the charge separation capability within the Ag@PTCA Schottky junction, thus providing a robust signal substrate for this biosensor. CoPP embedded within the double-strand DNA structure acted as the effective quencher. The double-amplification strategies containing rolling circle amplification (RCA) and DNAzyme-assisted Pb²⁺ cycling reaction were exquisitely designed and applied for upgrading the detection characteristics of the biosensor. The experimental findings demonstrated that the PEC signal was progressively recovered as the Pb²⁺ concentration increased from 500 fM to 5 μM, and the detection limit was 166.7 fM under optimal conditions, thus endowing the biosensor with the benefits of strong specificity and high selectivity. This method provides promising opportunities for detecting various heavy-metal ions in the fields of environmental monitoring, biological analysis, and medical research under complex conditions.

在这项工作中，通过应用银纳米颗粒@3,4,9,10-苝四羧酸（Ag@PTCA）肖特基结作为信号底物和钴四苯基卟啉（CoPP）作为信号淬灭剂，并结合核酸双扩增策略，构建了一种用于铅离子（Pbsup>2+</sup>）检测的特定且灵敏的照片电化学（PEC）生物传感器。肖特基结的强单向导电性和银纳米颗粒的表面等离子体共振（SPR）效应显著增强了Ag@PTCA肖特基结内的电荷分离能力，从而为该生物传感器提供了一个坚固的信号底物。嵌入双链DNA结构中的CoPP起到了有效的淬灭剂作用。精心设计并应用了包含滚环扩增（RCA）和DNAzyme辅助Pb<sup2+循环反应在内的双重扩增策略，以提高该生物传感器的检测性能。实验结果表明，随着Pb²⁺浓度从500 fM增加到5 μM，PEC信号逐渐恢复，在最佳条件下检出限为166.7 fM，从而赋予了该生物传感器强特异性和高选择性的优点。这种方法在环境监测、生物分析和医学研究等复杂条件下的重金属离子检测领域提供了有希望的机会。