Utilizing Cell-SELEX, as a Promising Strategy to Isolate ssDNA Aptamer Probes for Detection of <i>Staphylococcus aureus</i>

Abstract

<em>Staphylococcus aureus</em> is one of the most important pathogens in hospital acquired infections. Annually, many people are infected with <em>S. aureus</em> in hospitals. Rapid detection of this bacterium is extremely helpful in preventing and managing this bacterium mediated diseases. Aptamers are powerful probes, which can be used as a target explorer in a wide range of diagnostic systems. To isolate a specific aptamer against <em>S. aureus</em>, a library of single-stranded DNA molecules was designed, and enriched through Cell-SELEX procedure. In the Cell-SELEX, the DNA library was exposed to the <em>S. aureus</em> bacterium in 8 reiterative quadruple rounds including: binding, separation, elution and amplification. After 8 rounds, the PCR product was cloned and sequenced. Cloned aptameric sequences were evaluated through enzyme-linked oligonucleotide assay (ELONA), and a sequence with the best outcomes was selected as ideal aptamer. Eight rounds of Cell-SELEX procedure led to isolation of a specific ssDNA aptamer against <em>S. aureus</em> and named as “STAPT" (conflation of STAphylococcus and APTamer). Using ELONA technique, the detection limit of this aptamer was determined as 4 × 10³ CFU/ml. The aptamer “STAPT" showed the promising and potent abilities and features to be utilized as a bio-detection element likely in advanced detection systems. Although more extended researches are needed for this purpose.