Asymmetric PCR for good quality ssDNA generation towards DNA aptamer production

Aptamers are ssDNA or RNA that binds to wide variety of target molecules with high affinity and specificity produced by systematic evolution of ligands by exponential enrichment (SELEX). Compared to RNA aptamer, DNA aptamer is much more stable, favourable to be used in many applications. The most critical step in DNA SELEX experiment is the conversion of dsDNA to ssDNA. The purpose of this study was to develop an economic and efficient approach of generating ssDNA by using asymmetric PCR. Our results showed that primer ratio (sense primer:antisense primer) of 20:1 and sense primer amount of 10 to 100 pmol, up to 20 PCR cycles using 20 ng of initial template, in combination with polyacrylamide gel electrophoresis, were the optimal conditions for generating good quality and quantity of ssDNA. The generation of ssDNA via this approach can greatly enhance the success rate of DNA aptamer generation.