副溶血性弧菌是水产品中常见的食源性致病菌,其快速检测方法逐渐被开发,适配体作为一种新兴的特异性识别元件受到广泛关注。以副溶血性弧菌作为靶标菌进行了12轮细胞-指数富集配体系统进化技术(cell-systematic evolution of ligands by exponential enrichment,cell-SELEX),其中包括9轮正向筛选和3轮负向筛选,在每轮正筛中对PCR轮数和Lambada外切酶用量进行优化,筛选完成后进行核酸测序,并通过qPCR和流式细胞术多角度地对测序得到的序列性能进行验证。结果显示,F-28-10表现出较好的结合能力和特异性,且通过对PCR扩增轮数和Lambda外切酶用量优化后的cell-SELEX可以实现微生物特异性适配体的开发。研究结果为食源性致病微生物快速检测技术的开发提供了新的可利用的识别元件。
Chloramphenicol(CAP)is a potent antibiotic.Due to its side effects,CAP is currently banned in most countries,but it is still found in many food products and in the environment.Developing aptamer-based biosensors for the detection of CAP has interested many researchers.While both RNA and DNA aptamers were previously reported for CAP,they were all obtained by immobilization of the CAP base,which omitted the two chlorine atoms.In this work,DNA aptamers were selected using the libraryimmobilized method and free unmodified CAP.Three families of aptamers were obtained,and the best one named CAP1 showed a dissociation constant(K_(d))of 9.8μM using isothermal titration calorimetry(ITC).A fluorescent strand-displacement sensor showed a limit of detection(LOD)of 14μM CAP.Thioflavin T(ThT)staining allowed label-free detection of CAP with a LOD of 1μM in buffer,1.8μM in Lake Ontario water,and 3.6μM in a wastewater sample.Comparisons were made with previously reported aptamers,and ITC failed to show binding of a previously reported 80-mer aptamer.Due to the small size and well-defined secondary structures of CAP1,this aptamer will find analytical applications for environmental and food monitoring.
