Foodborne pathogens are a major cause of foodborne illness, leading to a growing food safety problem in public health. This work aims to develop a novel gold nanoparticles (AuNPs)-assisted multiplex PCR assay for rapid, simple and simultaneous detection of Salmonella typhimurium (S. typhimurium), Listeria monocytogenes (L. monocytogenes) and Escherichia coli O157:H7 (E. coli O157:H7), which are the top three foodborne pathogenic bacteria. Flower-shaped AuNPs (F-AuNPs) were used as a colorimetric sensor in this assay, based on PCR product that can help improve stability of the F-AuNPs in a certain concentration of salt solution. Detection of PCR product can be directly achieved by mixing it with F-AuNPs and NaCl, and the result is visible to the naked eye. Results showed that the optimal annealing temperature was 53.1 °C to amplify the three target pathogenic strains in multiplex PCR assay, and the optimal concentrations of the primer pairs were 0.4 μM for each of L. monocytogenes and E. coli O157:H7, and 0.2 μM for S. typhimurium. The colorimetric detection limit of PCR products by F-AuNPs was 3.125 ng μL⁻¹, and the detection time was approximately 10 min. Simultaneous detection limit of the multiplex PCR method was 10 pg μL⁻¹ for L. monocytogenes and S. typhimurium, and 50 pg μL⁻¹ for E. coli O157:H7. Compared with conventional multiplex PCR assay, the F-AuNPs-assisted assay is a convenient, rapid and simple visual detection method. The excellent performance of the colorimetric sensor shows potential application in on-site detection of foodborne pathogenic strains in food samples.

中文翻译：

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纳米金辅助多重PCR分析法同时检测鼠伤寒沙门氏菌，单核细胞增生性李斯特菌和大肠杆菌O157：H7

食源性病原体是食源性疾病的主要原因，导致公共卫生中日益严重的食品安全问题。这项工作旨在开发一种新型的金纳米颗粒（AuNPs）辅助的多重PCR检测方法，用于快速，简单和同时检测鼠伤寒沙门氏菌（S. typhimurium），单核细胞增生李斯特菌（L. monocytogenes）和大肠杆菌O157：H7（E. coli）O157：H7），是食源性致病性细菌中排名前三的细菌。在此测定中，基于PCR产物的花状AuNP（F-AuNPs）被用作比色传感器，可以帮助提高F-AuNPs在一定浓度的盐溶液中的稳定性。将PCR产物与F-AuNPs和NaCl混合可直接实现检测，结果肉眼可见。结果显示，在多重PCR分析中，最佳退火温度为53.1°C，以扩增三种目标致病菌株；单核细胞增生李斯特菌和大肠杆菌O157：H7的引物对的最佳浓度分别为0.4μM和0.2。鼠伤寒沙门氏菌为μM 。F-AuNPs对PCR产物的比色检测极限为3.125 ngμL ^-1，检测时间约为10分钟。对于单核细胞增生李斯特菌和鼠伤寒沙门氏菌，多重PCR方法的同时检测极限为10 pgμL ^{- 1，}对于大肠杆菌O157：H7，同时检测极限为50 pgμL ^-1。与传统的多重PCR检测相比，F-AuNPs辅助检测是一种便捷，快速且简单的视觉检测方法。比色传感器的出色性能显示了其在食品样品中食源性致病菌的现场检测中的潜在应用。