Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Biosens Bioelectron. 2010 Apr 15;25(8):1977-83. doi: 10.1016/j.bios.2010.01.020. Epub 2010 Jan 25.
A label-free immunosensor for the direct detection of cholera toxin (CT) at sub-attomolar level has been developed based on potential-step capacitance measurements. Anti-CT antibody was adsorbed on gold nanoparticles (AuNPs) incorporated on a polytyramine-modified gold electrode. The concentration of CT was determined by detecting the change of capacitance caused by the formation of antibody-antigen complexes. By using AuNPs adsorbed to the sensing surface, the signal was dramatically increased leading to a significantly more sensitive assay. In fact, under optimum conditions the immunosensor could detect CT concentration with a limit of detection of 9 x 10(-20)M or 0.09 aM, with a dynamic range between 0.1 aM and 10 pM. Good analytical reproducibility could be obtained by injecting CT up to 36 times with an RSD of 2.5%. In addition, good performance of the developed immunosensor was achieved when applied to turbid water samples collected from a local stream that were spiked with CT.
基于阶跃电容测量法，我们开发出了一种无需标记的免疫传感器，可以在亚皮摩尔级水平上直接检测霍乱毒素（CT）。将抗 CT 抗体吸附到聚邻苯二胺修饰的金电极上的金纳米粒子（AuNPs）上。通过检测抗体-抗原复合物形成引起的电容变化来确定 CT 的浓度。通过使用吸附在传感表面上的 AuNPs，信号得到了显著增强，从而使检测变得更加灵敏。事实上，在最佳条件下，该免疫传感器可以检测到浓度低至 9 x 10(-20)M 或 0.09 aM 的 CT，其动态范围在 0.1 aM 和 10 pM 之间。通过将 CT 注入多达 36 次，可获得良好的分析重现性，相对标准偏差（RSD）为 2.5%。此外，将该免疫传感器应用于从当地溪流中采集的混浊水样中添加 CT 的样品时，也能获得良好的性能。
