College of Biosystems Engineering and Food Science, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029, China.
Anal Chim Acta. 2011 Feb 14;687(1):89-96. doi: 10.1016/j.aca.2010.12.018. Epub 2010 Dec 21.
A label-free capacitive immunosensor based on quartz crystal Au electrode was developed for rapid and sensitive detection of Escherichia coli O157:H7. The immunosensor was fabricated by immobilizing affinity-purified anti-E. coli O157:H7 antibodies onto self-assembled monolayers (SAMs) of 3-mercaptopropionic acid (MPA) on the surface of a quartz crystal Au electrode. Bacteria suspended in solution became attached to the immobilized antibodies when the immunosensor was tested in liquid samples. The change in capacitance caused by the bacteria was directly measured by an electrochemical detector. An equivalent circuit was introduced to simulate the capacitive immunosensor. The immunosensor was evaluated for E. coli O157:H7 detection in pure culture and inoculated food samples. The experimental results indicated that the capacitance change was linearly correlated with the cell concentration of E. coli O157:H7. The immunosensor was able to discriminate between cellular concentrations of 10(2)-10(5) cfu mL(-1) and has applications in detecting pathogens in food samples. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were also employed to characterize the stepwise assembly of the immunosensor.
基于石英晶体金电极的无标记电容免疫传感器被开发用于快速灵敏地检测大肠杆菌 O157:H7。该免疫传感器通过将亲和纯化的抗大肠杆菌 O157:H7 抗体固定在石英晶体金电极表面的 3-巯基丙酸 (MPA) 自组装单层 (SAM) 上来制备。当将免疫传感器用于液体样品测试时，溶液中的细菌附着在固定化的抗体上。电化学检测器直接测量由细菌引起的电容变化。引入了一个等效电路来模拟电容免疫传感器。该免疫传感器用于纯培养和接种食品样品中大肠杆菌 O157:H7 的检测。实验结果表明，电容变化与大肠杆菌 O157:H7 的细胞浓度呈线性相关。该免疫传感器能够区分 10(2)-10(5) cfu mL(-1) 的细胞浓度，可用于检测食品样品中的病原体。还采用循环伏安法 (CV) 和电化学阻抗谱 (EIS) 来表征免疫传感器的逐步组装过程。
