Using an In₂O₃/WO₃ type-II heterojunction modified fluorine-doped tin oxide (FTO) electrode as the photoanode and CdS quantum dots (QDs)-polydopamine nanospheres (PDA NSs) as the secondary antibody (Ab₂) label, the photoelectrochemistry (PEC) sandwich immunosensing of the lung cancer marker CYFRA21-1 was studied. WO₃ nanoplates were prepared by a hydrothermal method, In₂O₃ nanoporous spheres were prepared by a hydrothermal method followed by calcination, and the In₂O₃/WO₃ type-II heterojunction with high PEC activity was prepared by ultrasonic mixing and cast-coating. PDA NSs with a high surface area can be loaded with abundant Ab₂ molecules and many CdS QDs with an energy level well matched with the heterojunction, so the photocurrent signal can be amplified by the formation of a sandwich immunostructure. Through the simulation experiments of photoelectrode-modified chitosan films of varying thickness, the effective transport distance of photogenerated charges is preliminarily discussed. Under the optimized conditions, the photocurrent was linear with the common logarithm of CYFRA21-1 concentration from 100 fg mL⁻¹ to 50 ng mL⁻¹, with a limit of detection of 56 fg mL⁻¹ (S/N = 3). The immunoassay of CYFRA21-1 in human serum samples gave satisfactory recovery results.

中文翻译：

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基于In2O3/WO3 II型异质结和CdS量子点-聚多巴胺纳米球标记的CYFRA21-1光电化学夹心免疫分析

以In ₂ O ₃ /WO ₃ II型异质结修饰的氟掺杂氧化锡(FTO)电极为光阳极，以CdS量子点(QDs)-聚多巴胺纳米球(PDA NSs)为二抗(Ab ₂ )标记，研究了肺癌标志物CYFRA21-1的光电化学（PEC）夹心免疫传感。采用水热法制备WO ₃纳米片，采用水热法制备In ₂ O ₃纳米多孔球后煅烧，In ₂ O ₃ /WO ₃采用超声混合和铸涂法制备了具有高 PEC 活性的 II 型异质结。具有高表面积的PDA NSs可以负载丰富的Ab ₂分子和许多能级与异质结匹配的CdS量子点，因此可以通过形成夹心免疫结构来放大光电流信号。通过不同厚度的光电极修饰壳聚糖膜的模拟实验，初步探讨了光生电荷的有效传输距离。在优化条件下，光电流与CYFRA21-1浓度的常用对数从100 fg mL ^-1到50 ng mL ^-1呈线性关系，检测限为56 fg mL ^-1（信噪比 = 3）。人血清样品中 CYFRA21-1 的免疫测定给出了令人满意的回收结果。