The present study demonstrates, development of ssDNA aptamers against whole cell of S. flexneri employing a whole bacterium-based Systemic Evolution of Ligands by Exponential Enrichment (SELEX). After ten rounds of SELEX, cell surface specific aptamer pool was cloned, sequenced and divided based on sequence similarities and secondary structure. Binding affinity of FITC labelled aptamer from different group were carried out by flow cytometry analysis. The dissociation constant (K_d) values for specific and higher binder were evaluated to range from 144 to 329 nM. Six high binding aptamers with lower dissociation constant was chosen for selectivity study. Aptamer SHI 23, SHI 37 and SHI 42 showed higher selectivity towards S. flexneri in comparison with other related bacteria. Further applicability of selected aptamer was proven by fluorescence assay for convenience detection of target cell from spiked water sample and natural contaminated water samples. Altogether, aptamer generated in this study can be alternative DNA ligands for detection of S. flexneri compared to available ligands.

本研究表明，采用基于全细菌的指数富集配体系统进化 (SELEX) 开发针对福氏链球菌全细胞的 ssDNA 适体。经过十轮SELEX后，根据序列相似性和二级结构对细胞表面特异性适体池进行克隆、测序和划分。通过流式细胞术分析不同组别FITC标记适体的结合亲和力。特异性和高级结合物的解离常数 ( Kd ₎值经评估范围为 144 至 329 nM。选择六种具有较低解离常数的高结合适体进行选择性研究。与其他相关细菌相比，适体 SHI 23、SHI 37 和 SHI 42 对福氏链球菌表现出更高的选择性。通过荧光测定证明了所选适体的进一步适用性，可方便地从加标水样和天然污染水样中检测靶细胞。总而言之，与现有配体相比，本研究中生成的适体可以作为检测福氏链霉的替代 DNA 配体。