利用SELEX技术筛选小檗碱核酸适配体及其亲和力表征

小檗碱是一种价格低廉且生物安全性良好的小分子化合物，筛选能与小檗碱互相作用的核酸片段，旨在开发新型遗传元件并拓展其在生物技术领域的应用。利用指数富集的配基系统进化技术（SELEX），经8轮实验从随机单链DNA文库中筛选出4条能与小檗碱高度特异性结合的核酸适配体。对其中两条重现性较好的适配体进行结构模拟分析表明，适配体序列富含鸟嘌呤和胞嘧啶且多形成茎环及G-四链体结构。亲和力测定结果显示，其中的2条核酸适配体与小檗碱作用的解离常数K_d都处于nmol级，表现出较高的亲和力，适配体S1的K_d值最小，仅为523 nmol/L，与小檗碱亲和力最大。

Systematic evolution of ligands by exponential enrichment (SELEX) screening and affinity characterization of berberine aptamers

Berberine (BBR) is a low-cost and biosafe small molecule. Screening of BBR-binding nucleic acid fragments holds promise for the development of novel genetic elements which might extend BBR's applications in industrial biotechnology. In this study, four aptamers with high specificity for BBR were acquired through eight rounds of systematic evolution of ligands by exponential enrichment (SELEX) screening. Structural simulation showed that the aptamer sequences were rich in guanine-cytosine (GC) and formed stem-ring and G-quadruplex structures. Affinity determination results demonstrated that the dissociation constants K_d of the two aptamers were at a nanomolar level, indicating their high affinity for BBR. Of screened two aptamers, the aptamer S1 displayed the lowest K_d value (523 nmol/L), indicating it had the highest affinity to BBR.