An automatic microfluidic system that continuously performs the systematic evolution of ligands by exponential enrichment

The systematic evolution of ligands by exponential enrichment (SELEX) technique has been extensively used to screen molecule-specific aptamers from combinatorial libraries of synthetic nucleic acids. Aptamers are single-stranded DNA or RNA, which have a high affinity to a large variety of molecules ranging from small drugs or metabolites to cells. Therefore, they have a variety of promising applications such as for diagnostics and targeted therapeutics. In this study, a new microfluidic chip was developed to perform continuous screening of DNA-based aptamers in an automatic format. When compared with the existing manual procedure, the developed microfluidic chip has several advantages including a rapid and efficient screening process, automation, and less consumption of samples/reagents. Experimental data showed that an aptamer specific to alpha-fetoprotein was successfully screened from a random DNA pool. The entire screening process (five continuous, repetitive rounds) can be completed within 6 h, which is much faster than the traditional methods (more than 15 h). An automatic, rapid and efficient SELEX process was performed by this developed microfluidic chip, which may enable a generalized platform for the fast screening of DNA-based biomarkers in the future.