Salmonella screening is a key to ensure food safety in poultry supply chains. Currently available Salmonella detection methods including culture, polymerase chain reaction and enzyme-linked immuno-sorbent assay could not achieve rapid, sensitive, and in-field detection. In this study, different strategies for separation and detection of Salmonella were proposed, compared, and improved based on our previous studies on immunomagnetic separation and impedance biosensor. First, the coaxial capillary for immunomagnetic separation of target bacteria was improved with less contamination, and 3 strategies based on the improved capillary and immunomagnetic nanoparticles were compared to separate the target bacteria from sample and form the magnetic bacteria. The experimental results showed that the strategy of capture in tube and separation in capillary was the most suitable with separation efficiency of approximately 88%. Then, the immune gold nanoparticles coated with urease were used to label the magnetic bacteria, resulting in the formation of enzymatic bacteria, which were injected into the capillary. After the urea was catalyzed by the urease on the enzymatic bacteria in the capillary, different electrodes were compared to measure the impedance of the catalysate and the screen-printed electrode with higher sensitivity and better stability was the most suitable. This impedance biosensor-based bacterial detection strategy was able to detect Salmonella as low as 102 CFU/mL in 2 h without complex operations. Compared to the gold standard culture method for practical screening of Salmonella in poultry supply chains, this proposed strategy had an accuracy of approximately 90% for 75 real poultry samples.

中文翻译：

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将阻抗生物传感器与免疫磁性分离相结合，用于快速筛查家禽供应链中的沙门氏菌。

沙门氏菌筛查是确保家禽供应链食品安全的关键。目前沙门氏菌检测方法包括培养法、聚合酶链反应法、酶联免疫吸附法等，无法实现快速、灵敏、现场检测。本研究在前期免疫磁分离和阻抗生物传感器研究的基础上，提出、比较和改进了沙门氏菌的不同分离和检测策略。首先，改进了用于目标细菌免疫磁性分离的同轴毛细管，污染更少，并比较了基于改进毛细管和免疫磁性纳米粒子的3种策略，以从样品中分离目标细菌并形成磁性细菌。实验结果表明，管内捕获、毛细管分离的策略最为合适，分离效率约为88%。然后，用包被脲酶的免疫金纳米粒子标记磁性细菌，形成酶细菌，并将其注射到毛细血管中。尿素在毛细管内的酶菌上被尿素酶催化后，通过比较不同的电极来测量催化剂的阻抗，以灵敏度较高、稳定性较好的丝网印刷电极最为合适。这种基于阻抗生物传感器的细菌检测策略能够在 2 小时内检测出低至 102 CFU/mL 的沙门氏菌，无需复杂的操作。与在家禽供应链中实际筛查沙门氏菌的金标准培养方法相比，该策略对 75 个真实家禽样本的准确度约为 90%。