Progress of Aptamer Screening Techniques Based on Microfluidic Chips

Aptamers are single-stranded DNA or RNA molecules that can specifically bind to defined targets, and has been widely used in the fields of biological separation and analysis, clinical diagnosis, and targeted therapy, and so on. The development of aptamers is closely related to the progress of screening techniques. Based on the systematic evolution of ligands by exponential enrichment (SELEX), a variety of in vitro aptamer screening techniques, such as magnetic beads-based SELEX and capillary electrophoresis- SELEX, have been developed and several specific and high-affinity aptamers for targets can be obtained. However, these methods are limited by multiple screening rounds, long screening cycles, large sample consumption, and low efficiency in screening aptamers for small molecules. On the other hand, the microfluidic chip possesses the characteristics of small size, high throughput and easy integration, which can solve the above-mentioned problems of SELEX to a certain extent, and realize the rapid and high-throughput screening of aptamers. Based on the summary of SELEX and the key technical points, this review focuses on the progress of SELEX techniques based on microfluidic chips and microarray chips, and summarizes the aspects of SELEX needing to be strengthened in the future.