Selection of Aptamers against live E.coli Cells using Cell SELEX

Abstract

Aptamers are oligonucleotides that bind with great specificity and affinity to a target molecule. These oligonucleotides are produced through the course of Systemic Evolution of Ligands by Exponential Enrichment (SELEX). SELEX is a combinatorial chemistry technique used to generate a random DNA or RNA library, which is then incubated with a target molecule. The binding aptamers are divided from the nonbinding random pool DNA/aptamers, and then amplified via polymerase chain reaction (PCR). Double stranded DNA aptamer molecules have been used to select against purified target molecules; in this study we have developed a selection technique using live E. coli cells as a target and using Kluyveromyces lactis, Bacillus subtilis, and Enterobacter aerogenes as negative controls. Aptamer pools obtained from approximately 7–9 rounds of Cell SELEX demonstrated an affinity for E.coli cells when tested via flow cytometry and fluorescence detection.