Photocathodic immunoassays show brilliant prospect for practical detection in biological matrix owning to the inherent strength against signal interference from potential reductive molecules. However, their exploration with advanced and efficient signaling mechanism is still barren. We herein report an enhanced photocathodic immunoassay via utilizing bilirubin oxidase (BOD) labeling to trigger an illustrious signaling mechanism of oxygen reduction reaction (ORR). The target model of prostate-specific antigen (PSA, Ag) was employed to exemplify this platform. Typically, the fabricated NiO/CdSe/Au hybrid photocathode served as the substrate to anchor capture antibody (Ab₁). In order to increase host loading, abundant BOD molecules were labeled on signal antibody (Ab₂) with the assistance of carbon nanotube (CNT), forming the Ab₂-BOD/CNT conjugate. When specific immunological recognition occurred, the BOD labeling could efficiently catalyze the reduction reaction of electron acceptor of dissolved oxygen, causing dramatically promoted cathodic photocurrent signal. By introducing this ingenious signaling mechanism triggered by BOD, enhanced photocathodic immunoassay with high sensitivity and accuracy in biological matrix was developed. This work pioneers an effective but general strategy for the design of advanced photocathodic bioassays for different targets of interest.

光阴极免疫测定法具有固有的抗潜在还原性分子信号干扰的强度，在生物基质中的实际检测显示出广阔的前景。然而，它们对具有先进而有效的信号机制的探索仍然是贫乏的。我们在这里报告通过利用胆红素氧化酶（BOD）标记来触发氧还原反应（ORR）的杰出信号传导机制的增强的光阴极免疫测定。前列腺特异性抗原（PSA，Ag）的目标模型被用来例证该平台。通常，制造的NiO / CdSe / Au杂化光电阴极用作锚定捕获抗体（Ab ₁）的底物。为了增加宿主载量，在信号抗体（Ab ₂）在碳纳米管（CNT）的帮助下形成Ab ₂ -BOD / CNT共轭物。当发生特定的免疫学识别时，BOD标记可有效催化溶解氧的电子受体的还原反应，从而显着促进阴极光电流信号。通过引入由BOD触发的这种巧妙的信号传导机制，开发了在生物基质中具有高灵敏度和准确性的增强型光阴极免疫测定法。这项工作开创了一种有效但通用的策略，可针对不同的目标设计先进的光阴极生物测定。