Extracellular respiring bacteria (ERB) are a group of bacteria capable of transferring electrons to extracellular acceptors and have important application in environmental remediation. In this study, a decomposable quantum-dots (QDs)/DNA nanosphere probe was developed for rapid and ultrasensitive detection of ERB. The QDs/DNA nanosphere was self-assembled from QDs-streptavidin conjugate (QDs-SA) and Y-shaped DNA nanostructure that is constructed based on toehold-mediated strand displacement. It can release numerous fluorescent QDs-SA in immunomagnetic separation (IMS)-based immunoassay via simple biotin displacement, which remarkably amplifies the signal of antigen-antibody recognizing event. This QDs/DNA-nanosphere-based IMS-fluorescent immunoassay is ultrasensitive for model ERB Shewanella oneidensis, showing a wide detection range between 1.0 cfu/mL and 1.0 × 10⁸ cfu/mL with a low detection limit of 1.37 cfu/mL. Moreover, the proposed IMS-fluorescent immunoassay exhibits high specificity, acceptable reproducibility and stability. Furthermore, the proposed method shows acceptable recovery (92.4–101.4%) for detection of S. oneidensis spiked in river water samples. The proposed IMS-fluorescent immunoassay advances an intelligent strategy for rapid and ultrasensitive quantitation of low-abundance analyte and thus holds promising potential in food, medical and environmental applications.

细胞外呼吸细菌（ERB）是一组能够将电子转移到细胞外受体的细菌，在环境修复中具有重要的应用。在这项研究中，可分解的量子点（QDs）/ DNA纳米球探针被开发用于快速和超灵敏的ERB检测。QDs / DNA纳米球由QDs-链霉亲和素共轭物（QDs-SA）和基于脚趾介导的链置换构建的Y形DNA纳米结构自组装而成。它可以通过简单的生物素置换在基于免疫磁分离（IMS）的免疫分析中释放大量荧光QDs-SA，从而显着放大抗原抗体识别事件的信号。基于QDs / DNA-Nanosphere的IMS荧光免疫测定法对模型ERB沙瓦氏假单胞菌超敏感的检测范围在1.0 cfu / mL到1.0×10 ⁸ cfu / mL之间，检测下限为1.37 cfu / mL。而且，所提出的IMS-荧光免疫测定法显示出高特异性，可接受的再现性和稳定性。此外，用于检测的所提出的方法示出了可接受的回收率（92.4-101.4％）S. oneidensis中掺入河水样品英寸 拟议的IMS荧光免疫测定技术为快速，超灵敏定量低丰度分析物提供了一种智能策略，因此在食品，医疗和环境应用中具有广阔的前景。