Accurate detection of L-Cysteine (Cyst) is critical because it is a recognized marker associated with diseases such as liver damage and kidney failure. Photoelectrochemical (PEC) sensor is an emerging strategy for biochemical analysis. However, the sensitivity of PEC sensor is limited by the high recombination rate of photogenerated electron-hole pairs. In this study, Au-mediated Z-scheme TiO₂-Au-BiOI (HTNTs-Au-BOI) photoelectrochemical sensing platform for Cyst detection is proposed. Au NPs with plasmon resonance effect not only boost the light absorption but also facilitate the formation of Z-heterojunction HTNTs-Au-BOI through its own mediating effect. The Z-heterostructure with built-in electric field dramatically suppress the recombination of photogenerated electron-hole pairs and improve the sensitivity of the sensor. Meanwhile, the dual-specificity of Bi-S and Au-S bonds achieves a highly selective and sensitive detection of Cyst. The PEC sensor shows a wide linearity detection range of 80 nM-200 μM with a detection limit of 70 nM. The sensor also shows good results in the detection of serum samples, with a relative standard deviation (RSD) of 0.68–7.3 %.

L-半胱氨酸（Cyst）的准确检测至关重要，因为它是与肝损伤和肾衰竭等疾病相关的公认标志物。光电化学（PEC）传感器是一种新兴的生化分析策略。然而，PEC传感器的灵敏度受到光生电子-空穴对的高复合率的限制。在本研究中，提出了用于囊肿检测的Au介导的Z型TiO _{2 -Au-BiOI（HTNTs-Au-BOI）光电化学传感平台。}具有等离子体激元的金纳米粒子共振效应不仅促进光吸收，而且通过其自身的中介作用促进Z异质结HTNTs-Au-BOI的形成。具有内置电场的Z异质结构极大地抑制了光生电子空穴对的复合，提高了传感器的灵敏度。同时，Bi-S和Au-S键的双重特异性实现了Cyst的高选择性和灵敏检测。PEC 传感器具有 80 nM-200 μM 的宽线性检测范围，检测限为 70 nM。该传感器在血清样品的检测中也显示出良好的结果，相对标准偏差（RSD）为0.68-7.3%。