为实现大肠杆菌O157∶H7早期现场的快速检测,该试验通过化学还原法与介导生长法制备了AuNPs与AuNFs作为标记探针,建立2种用于大肠杆菌O157∶H7现场快速检测的免疫层析试纸条,并对2种试纸条的的灵敏度、特异性和准确性进行检测。结果显示,所建立的2种免疫层析方法均可在15 min内检出食品中的大肠杆菌O157∶H7,其中AuNP试纸条最低检出限为3.2×105 CFU/mL,AuNFs试纸条最低检出限为3.2×104 CFU/mL,与单增李斯特菌、沙门氏菌、坂崎肠杆菌等常见食源性致病菌没有交叉反应。对人工污染果冻、牛奶和牛肉等样品AuNPs试纸条分别在前增菌5、6、5 h时检出,AuNFs试纸条分别在前增菌5、5、4 h时检出,且不受食品复杂机制的影响。结果表明,所建立的2种免疫层析试纸条灵敏度高、特异性强、操作简便,适用于大肠杆菌O157∶H7现场快速检测。
Escherichia coli O157∶H7 is a common foodborne pathogen, which can spread through fecal-oral transmission. Humans can be infected by ingesting foods and water contaminated with E. coli O157∶H7, which can cause various symptoms. Therefore, in order to detect E. coli O157∶H7 in the early stage, AuNPs and AuNFs were prepared as labeled probes by chemical reduction method and mediated growth method, and two immunochromatographic test strips for rapid detection of E. coli O157∶H7 were established. The sensitivity, specificity, and accuracy of two test strips were tested. The results showed that E. coli O157: H7 in food could be detected within 15 min by both methods. The lowest detection limits of AuNP and AuNFs were 3.2×105 and 3.2×104 CFU/mL, respectively. There was no cross reaction with common foodborne pathogens such as Listeria monocytogenes, Salmonella typhimurium, and Enterobacter sakazakii. AuNPs and AuNFs were detected in the samples of artificially contaminated jelly, milk, and beef after 5, 6 and 5 h, respectively, which were not affected by the complex mechanism of food. The results showed that both strips had high sensitivity, specificity, and simple operation, which were suitable for rapid detection of E. coli O157∶H7 on-site. This research provides a new idea for the detection of other bacteria and viruses.
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