earticle

영어

Aptamers are powerful capturing probes against various targets such as proteins, small organic compounds, metal ions, and even cells. In this study, we isolated and characterized the ssDNA aptamers against E. coli. Total twenty eight ssDNAs were isolated after 10 rounds selection via bacterial cell-SELEX process. Other bacterial cells (Klebsiella pneumoniae, Citrobacter freundii, Enterobacter aerogenes, and Staphylococcus epidermidis) were used for counter selection to enhance the specificity of ssDNA aptamers against E. coli. With priority based-on 2D-structural prediction, ten ssDNA sequences were experimented for their affinity and specificity.. Finally, four ssDNA aptamers showed high affinity and specificity to E. coli The dissociation constant (Kd) of these four ssDNA aptamers to E. coli were estimated in a range of 12.4 to 25.2 nM, and they didn't bound to other bacterial cells including four counter cells. For other E. coli strains, they showed a similar or slightly weaker affinity compared with target strain. Based on the competitive binding assay, we assumed that two among four aptamers may bind to similar moiety on the surface of E. coli. In addition, the aptamer cocktails composed with selected aptamer pools showed a higher binding signal to E. coli compared with using only single aptamer.