基于免疫纳米颗粒强化的压电免疫传感器检测大肠杆菌O157︰H7

摘要：【目的】结合纳米技术建立检测大肠杆菌（Escherichia coli）O157︰H7高灵敏检测技术。【方法】采用化学共沉淀法制备出核心粒径约为10 nm的免疫纳米磁颗粒，柠檬酸钠还原法制备粒径约为20 nm的免疫胶体金。压电免疫传感器通过金黄色葡萄球菌蛋白A（Protein A from Staphylococcus aureus SPA）法将抗体固定于石英晶振上，两种免疫纳米颗粒借助不同的抗体连接于传感器上对检测频率信号进行放大。【结果】SPA在石英晶振上的最佳固定浓度和时间为1.2 mg/mL和40 min，抗体的最佳固定浓度和时间为1.0 mg/mL和60 min。压电免疫传感器通过两种免疫纳米颗粒的放大作用，使其对大肠杆菌O157︰H7的检测限从104 cfu/mL提高到101 cfu/mL。【结论】免疫纳米颗粒强化对压电免疫传感器的检测频率信号具有很好的放大效应，可以明显提高其检测灵敏度。

Detection of Escherichia coli O157:H7 with piezoelectric immunosensor based on enhancement with immuno-nanoparticles

Abstract: Objective] We developed a sensitive method to detect Escherichia coli O157:H7 based on enhancement with immuno-nanoparticles. Method] About 10 nm ultrafine immunomagnetic particles were prepared by a co-precipitation method, about 20 nm immuno-colloid-gold was prepared by sodium citrate reduction. The immunosensor was fabricated by using Protein A from Staphylococcus aureus (SPA) for the antibody immobilization. Two immuno-nanoparticles by two antibodies were used to amplify frequency changing. Result] The most suitable immobilization concentration and time for SPA was 1.2 mg/ml and 40 min, and dose for the antibody was 1.0 mg/ml and 60 min. With the signal amplification of the two immuno-nanoparticles, the detection limit of E. coli O157 : H7 was increased from 104 colony-forming units (cfu) /mL to 101 cfu/mL. Conclusion] The prepared immuno-nanoparticles might be used to significantly amplify the frequency signal of the piezoelectric immunosensor and improve the detect sensitivity.