The sensitivity, accuracy, and stability of a photoelectrochemical (PEC) immunosensor directly depends on the type of sensing substrate and the efficiency of the recognition model in immobilizing biological elements within multilayer assemblies. In this work, a split-type PEC immunosensor integrating Ag nanoparticles-modified ZIF-8 (ZIF-8@Ag NPs)-assisted cation-exchange and Fe₂O₃/ZnIn₂S₄ nanoarrays (NAs) as well-ordered sensing substrate and photoactive material was developed for the detection of carbohydrate antigen 72–4 (CA72–4), a novel gastric cancer target. With effectively harvesting visible light, the stability signal output and the rapid carrier separation, the Z-Scheme Fe₂O₃/ZnIn₂S₄ NAs heterojunction was successfully grown on an indium tin oxide (ITO) electrode as the signal converter and sensing substrate via two-step solvothermal method. The ZIF-8@Ag NPs were employed as the signal label to release silver ions (Ag⁺), relying on the acidolysis in the 96-well plate. The released Ag⁺ initiated a cation-exchange (CE) reaction with the Fe₂O₃/ZnIn₂S₄ NAs, forming Fe₂O₃/ZnIn₂S₄/Ag₂S ternary complexes with higher photocurrent density. This resulted in a positive correlation trend between CA72–4 concentration (0.01 U/mL to 100 U/mL), and improved the recognition sensitivity of the sensor to trace target, with the limit of detection is 0.0032 U/mL. This work represents an important advancement in overcoming the limitations of multilayer assembly in constructing immunosensors, providing a valuable reference for trace detection of low-abundance disease-related biomarkers.

中文翻译：

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集成 ZIF 8@Ag NPs 辅助阳离子交换和 Fe2O3/ZnIn2S4 纳米阵列的分体式光电化学免疫传感器，用于检测碳水化合物抗原 72-4


光电化学 （PEC） 免疫传感器的灵敏度、准确性和稳定性直接取决于传感基质的类型以及识别模型在多层组件中固定生物元件的效率。在这项工作中，开发了一种分体式 PEC 免疫传感器，将 Ag 纳米颗粒修饰的 ZIF-8 （ZIF-8@Ag NPs） 辅助阳离子交换和 Fe₂O₃/ZnIn₂S₄ 纳米阵列 （NAs） 作为有序的传感底物和光活性材料集成在一起，用于检测碳水化合物抗原 72-4 （CA72-4），一种新型胃癌靶点。通过两步溶剂热法，在作为信号转换器和传感衬底的氧化铟锡 （ITO） 电极上成功生长了 Z-Scheme Fe₂O₃/ZnIn₂S₄ NAs 异质结，有效地捕获了可见光，信号输出稳定，载流子分离迅速。采用 ZIF 8@Ag NPs 作为信号标记物，依靠 96 孔板中的酸解释放银离子 （Ag⁺）。释放的 Ag⁺ 引发了与 Fe₂O₃/ZnIn₂S₄ NAs 的阳离子交换 （CE） 反应，形成具有更高光电流密度的 Fe₂O₃/ZnIn₂S₄/Ag_{2 S 三}元配合物。这导致 CA72–4 浓度 （0.01 U/mL 至 100 U/mL） 呈正相关趋势，提高了传感器对痕量目标的识别灵敏度，检测限为 0.0032 U/mL。 这项工作代表了克服构建免疫传感器时多层组装局限性的重要进展，为低丰度疾病相关生物标志物的痕量检测提供了有价值的参考。