Construction of a microfluidic SELEX platform for efficient screening of advanced glycation end products aptamer

Aptamers, as a kind of recognition molecules with stable nature and excellent binding ability, are usually obtained by systematic evolution of ligands by exponential enrichment (SELEX). However, the traditional SELEX suffers from the problems of low screening efficiency as well as excessive number of screening rounds, making the screening a cumbersome process, which greatly restricts the application and development of aptamers. Here, a microfluidic SELEX platform based on capture SELEX was designed and developed to make the screening more integrated and convenient. Nε-carboxymethyl lysine (CML) and Nε-carboxyethyl lysine (CEL), were selected as targets for screening, and candidate aptamers were identified after eight rounds of screening using the microfluidic SELEX platform. Following isothermal titration calorimetry (ITC) and SYBR GREEN I (SGI) analysis, aptamer S2 was identified with the highest affinity and specificity. Aptamer S2 was further optimized based on the binding sites explored by molecular docking. Eventually, the truncated aptamer S2-40 was obtained, which was superior to S2 in terms of affinity and specificity with dissociation constant (Kd) of 6.65 ± 3.07 μM (ITC) and 42.1 ± 9.34 nM (SGI), respectively. This indicated that the microfluidic SELEX platform offers a more integrated and convenient approach to aptamer screening.