Herein we designed a novel photoelectrochemical sensing platform based on Fe³⁺ doped ZnO-Ag photocatalyst (Fe³⁺/ZnO-Ag) for ultrasensitive Hg²⁺ detection by using exonuclease III-assisted target recycling and DNAzyme-catalyzed amplification. Firstly, Fe³⁺/ZnO-Ag was synthesized to provide photocurrent under visible light irradiation. Secondly, target Hg²⁺ was determined by hairpin DNA probes on the Fe³⁺/ZnO-Ag modified ITO based on T-Hg²⁺-T, and then Hg²⁺ was released by the digestion of exonuclease III to double-stranded DNA. Finally, the photocurrent markedly decreased due to catalysis of hemin/G-quadruplex toward 4-chloro-1-naphthol. Under optimal conditions, the photocurrents were linearly related to Hg²⁺ concentrations form 0. 5 nM to 100 nM with a detection limit of 0. 1 nM at the 3S_blank criterion. More importantly, the developed biosensor exhibited good selectivity, repeatability, and stability, meanwhile, this analysis platform held great potential for testing real water samples in future.

本文中，我们设计了一种新型的基于Fe ³⁺掺杂的ZnO-Ag光催化剂（Fe ³⁺ / ZnO-Ag）的光电化学传感平台，通过使用核酸外切酶III辅助的靶标回收和DNAzyme催化的扩增对Hg ²⁺进行超灵敏检测。首先，合成Fe ³⁺ / ZnO-Ag在可见光照射下提供光电流。其次，通过发夹DNA探针在T 3 H ²⁺ -T上的Fe ³⁺ / ZnO-Ag修饰的ITO上确定目标Hg ²⁺，然后确定Hg ²⁺通过将核酸外切酶III消化成双链DNA而释放出β-内酰胺。最后，由于血红素/ G-四链体向4-氯-1-萘酚的催化作用，光电流显着降低。在最佳条件下，光电流与Hg ²⁺浓度从0. 5 nM到100 nM呈线性关系，在3 S_空白标准下检测限为0. 1 nM 。更重要的是，开发的生物传感器具有良好的选择性，可重复性和稳定性，同时，该分析平台在将来测试实际水样方面具有巨大的潜力。