Xu Meng, Wang Ronghui, Li Yanbin
Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA; Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
Talanta. 2016;148:200-8. doi: 10.1016/j.talanta.2015.10.082. Epub 2015 Oct 28.
Foodborne pathogens have continuously been a serious food safety issue and there is a growing demand for a rapid and sensitive method to screen the pathogens for on-line or in-field applications. Therefore, an impedimetric immunosensor based on the use of magnetic beads (MBs) for separation and a screen-printed interdigitated microelectrode (SP-IDME) for measurement was studied for the rapid detection of Escherichia coli O157:H7 and Salmonella Typhimurium in foods. Streptavidin coated MBs were functionalized with corresponding biotinylated antibodies (Ab) to capture the target bacteria. The glucose oxidase (GOx)-Ab conjugates were employed to label the MBs-Ab-cell complexes. The yielded MBs-Ab-cell-Ab-GOx biomass was mixed with the glucose solution to trigger an enzymatic reaction which produced gluconic acid. This increased the ion strength of the solution, thus decreasing the impedance of the solution measured on the SP-IDME. Our results showed that the immunosensor was capable of specifically detecting E. coli O157:H7 and S. Typhimurium within the range of 10(2)-10(6) cfu ml(-1) in the pure culture samples. E. coli O157:H7 in ground beef and S. Typhimurium in chicken rinse water were also examined. The limits of detection (LODs) for the two bacteria in foods were 2.05×10(3) cfu g(-1) and 1.04×10(3) cfu ml(-1), respectively. This immunosensor required only a bare electrode to measure the impedance changes, and no surficial modification on the electrode was needed. It was low-cost, reproducible, easy-to-operate, and easy-to-preserve. All these merits demonstrated this immunosensor has great potential for the rapid and on-site detection of pathogenic bacteria in foods.
食源性病原体一直是一个严重的食品安全问题，对于一种能够快速、灵敏地筛选病原体以用于在线或现场应用的方法的需求也在不断增长。因此，研究了一种基于使用磁珠（MBs）进行分离和丝网印刷叉指微电极（SP-IDME）进行测量的阻抗免疫传感器，用于快速检测食品中的大肠杆菌O157:H7和鼠伤寒沙门氏菌。用相应的生物素化抗体（Ab）对链霉亲和素包被的磁珠进行功能化，以捕获目标细菌。使用葡萄糖氧化酶（GOx）-Ab缀合物标记磁珠-Ab-细胞复合物。将产生的磁珠-Ab-细胞-Ab-GOx生物量与葡萄糖溶液混合，引发酶促反应，产生葡萄糖酸。这增加了溶液的离子强度，从而降低了在SP-IDME上测量的溶液阻抗。我们的结果表明，该免疫传感器能够在纯培养样品中特异性检测10(2)-10(6) cfu ml(-1)范围内的大肠杆菌O157:H7和鼠伤寒沙门氏菌。还检测了碎牛肉中的大肠杆菌O157:H7和鸡肉冲洗水中的鼠伤寒沙门氏菌。食品中这两种细菌的检测限（LOD）分别为2.05×10(3) cfu g(-1)和1.04×10(3) cfu ml(-1)。这种免疫传感器仅需一个裸电极来测量阻抗变化，无需对电极进行表面修饰。它成本低、可重复、易于操作且易于保存。所有这些优点表明，这种免疫传感器在快速现场检测食品中的病原菌方面具有巨大潜力。
