Marine Biotechnology and Bioproducts Laboratory, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India.
Electrodics and Electrocatalysis Division, CSIR - Central Electrochemical Research Institute, Karaikudi 630003, Tamil Nadu, India.
Mater Sci Eng C Mater Biol Appl. 2020 Sep;114:111071. doi: 10.1016/j.msec.2020.111071. Epub 2020 May 12.
Epidemic Salmonellosis contracted through the consumption of contaminated food substances is a global concern. Thus, simple and effective diagnostic methods are needed. Magnetosome-based biosensors are gaining attention because of their promising features. Here, we developed a biosensor employing a magnetosome-anti-Salmonella antibody complex to detect lipopolysaccharide (somatic "O" antigen) and Salmonella typhimurium in real samples. Magnetosome was extracted from Magnetospirillum sp. RJS1 and characterized by microscopy. The magnetosome samples (1 and 2 mg/mL) were directly conjugated to anti-Salmonella antibody (0.8-200 μg/mL) and confirmed by spectroscopy and zeta potential. The concentrations of magnetosome, antibody and lipopolysaccharide were optimized by ELISA. The 2 mg/mL-0.8 μg/mL magnetosome-antibody complex was optimal for detecting lipopolysaccharide (0.001 μg/mL). Our assay is a cost-effective (60%) and sensitive (50%) method in detection of lipopolysaccharide. The optimized magnetosome-antibody complex was applied to an electrode surface and stabilized using an external magnetic field. Increased resistance confirmed the detection of lipopolysaccharide (at 0.001-0.1 μg/mL) using impedance spectroscopy. Significantly, the R value was 0.960. Then, the developed prototype biosensor was applied to food and water samples. ELISA confirmed the presence of lipopolysaccharide in homogenized infected samples and cross reactivity assays confirmed the specificity of the biosensor. Further, the biosensor showed low detection limit (10 CFU/mL) in water and milk sample demonstrating its sensitivity. Regression coefficient of 0.974 in water and 0.982 in milk was obtained. The magnetosome-antibody complex captured 90% of the S. typhimurium in real samples which was also confirmed in FE-SEM. Thus, the developed biosensor is selective, specific, rapid and sensitive for detection of S. typhimurium.
通过食用受污染的食物物质而感染的沙门氏菌病是一个全球性的问题。因此，需要简单有效的诊断方法。基于磁小体的生物传感器因其有前景的特性而受到关注。在这里，我们开发了一种生物传感器，该传感器使用磁小体-抗沙门氏菌抗体复合物来检测实际样品中的脂多糖（躯体“O”抗原）和鼠伤寒沙门氏菌。从 Magnetospirillum sp. RJS1 中提取磁小体并通过显微镜进行了表征。将磁小体样品（1 和 2 mg/mL）直接与抗沙门氏菌抗体（0.8-200 μg/mL）共轭，并通过光谱和zeta 电位进行了确认。通过 ELISA 优化了磁小体、抗体和脂多糖的浓度。2 mg/mL-0.8 μg/mL 的磁小体-抗体复合物是检测脂多糖（0.001 μg/mL）的最佳选择。我们的测定方法是一种具有成本效益（60%）和灵敏度（50%）的方法，可用于检测脂多糖。优化的磁小体-抗体复合物被应用于电极表面，并通过外部磁场进行稳定。阻抗谱的电阻增加证实了脂多糖（在 0.001-0.1 μg/mL 范围内）的检测。值得注意的是，R 值为 0.960。然后，将开发的原型生物传感器应用于食品和水样。ELISA 证实了均质感染样品中脂多糖的存在，交叉反应性测定证实了生物传感器的特异性。此外，该生物传感器在水和牛奶样品中显示出较低的检测限（10 CFU/mL），证明了其灵敏度。在水中和牛奶中的回归系数分别为 0.974 和 0.982。在真实样品中，磁小体-抗体复合物捕获了 90%的鼠伤寒沙门氏菌，这在 FE-SEM 中也得到了证实。因此，所开发的生物传感器具有选择性、特异性、快速性和对鼠伤寒沙门氏菌的敏感性。
