Sensitive, rapid, and reliable detection of bacteria has always been pursued due to the great threat of the bacteria to human health. In this study, a convenient one-step strategy for detecting Salmonella typhimurium was developed. Immunomagnetic nanospheres (IMNS) and immunofluorescent nanospheres (IFNS) were used to specifically capture and recognize S. typhimurium simultaneously. After magnetic separation, the sandwich immune complexes (IMNS–bacteria–IFNS) were detected under a fluorescence microscope with a detection limit as low as ca. 10 CFU/mL. When they were detected by fluorescence spectrometer, a linear range was exhibited at the concentration from 10⁵ to 10⁷ CFU/mL with R² = 0.9994. Compared with the two-step detection strategy, in which the bacteria were first captured with the IMNS and subsequently identified with the IFNS, this one-step strategy simplified the detection process and improved the sensitivity. Escherichia coli and Shigella flexneri both showed negative results with this method, indicating that this method had excellent selectivity and specificity. Moreover, this method had strong anti-interference ability, and it had been successfully used to detect S. typhimurium in synthetic samples (milk, fetal bovine serum, and urine), showing the potential application in practice.

中文翻译：

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磁性捕获和功能性纳米球的荧光识别耦合一步法检测鼠伤寒沙门氏菌

由于细菌对人类健康的巨大威胁，一直追求灵敏，快速和可靠的细菌检测。在这项研究中，开发了一种便捷的一步法检测鼠伤寒沙门氏菌。免疫磁纳米球（IMNS）和免疫荧光纳米球（IFNS）用于同时特异性捕获和识别鼠伤寒沙门氏菌。磁分离后，在荧光显微镜下检测到夹心免疫复合物（IMNS –细菌– IFNS），检出限低至约。10 CFU /毫升。当用荧光光谱仪检测它们时，在R ²为10 ⁵到10 ⁷ CFU / mL的浓度范围内表现出线性范围= 0.9994。与首先通过IMNS捕获细菌然后通过IFNS进行细菌识别的两步检测策略相比，这种单步策略简化了检测过程并提高了灵敏度。大肠杆菌和弗氏志贺氏菌均显示阴性结果，表明该方法具有优异的选择性和特异性。而且，该方法具有很强的抗干扰能力，已成功用于合成样品（牛奶，胎牛血清和尿液）中鼠伤寒沙门氏菌的检测，在实践中具有潜在的应用前景。