Xu Liguang

Gold nanoparticle-based strip sensor for multiple detection of twelve Salmonella strains with a genus-specific lipopolysaccharide antibody

In this study, an innovative competitive immunochromatographic strip sensor was developed for rapid detection of Salmonella based on a genus-specific antilipopolysaccharide (LPS) monoclonal antibody (mAb) and the heterogeneous coating antigen of a LPS-bovine serum albumin conjugate. Gold nanoparticles labeled anti-LPS mAb specifically reacted with the conserved outer core of the Salmonella LPS in the sample and the color formed on the T line was negatively correlated with the number of Salmonella cells. The sensitivity of Ra mutant LPS (without O-specific chains but has the conserved outer core) was 25 ng mL–1, which explained the detection of Salmonella at the genus level. Based on the gray values on the test line, the limit of detection of Salmonella was 103 colony-forming unit (CFU) for all twelve typical strains of Salmonella. The analysis of common Gram-negative and Gram-positive bacteria demonstrated that the strip assay was specific to Salmonella. A milk sample test showed that Salmonella at a low level (1–5 CFU mL–1) was detected without complex biochemical confirmation steps, sophisticated instruments and professional training.摘要沙门氏菌属是全球关注的重要食源性致病菌之一. 本文以沙门氏菌属特异性脂多糖抗体与胶体金纳米粒子进行偶联, 并进行固相化, 装配了适合于快速、可视化分析的金标试纸传感器. 裸眼观察下, 金标试纸条可以识别浓度低至25 ng mL−1的沙门氏菌属脂多糖. 结合灰 度扫描分析, 金标试纸对受试的12种沙门氏菌的敏感性可达到103 菌落形成单位(CFU). 对牛奶样品进行12 h的富集孵育, 该金标试纸条对 沙门氏菌的检测灵敏度可达1个CFU. 金标试纸传感器无需复杂的前处理过程和专业设备, 操作简单, 有效地提高了致病菌的检测效率.