ABSTRACT
Screening aptamers using nano-materials ( such as graphene oxide, gold nanoparticle, carbon nano-tube, etc. ) that can quench fluorescence and absorb single stranded DNA using hydrogen bond, π-πbond, charge transfer, and other non-covalent ways to combine with ssDNA, but without other conformational DNA, can excellently separate specific aptamers from non-specific ones. In this case, we can shorten the cycle numbers, enhance the success rate, and reduce the labour intensity of systematic evolution of ligands by exponential enrichment ( SELEX) . Especially for small molecular target, due to its difficulty in immobilization and small size, it is difficult to use traditional methods such as SPR-SELEX or affinity-SELEX for screening. In this experiment, polydopamine nanospheres ( MNPs@PDAs) were used to screen the Lomefloxacin. Also, we used magnetic separation technique to screen small molecular target rapidly. The interaction between aptamer candidates and the target could be monitored by recovery ratio of ssDNA and the whole MNPs@PDAs-SELEX process was performed through seven-round selection. As a result, we successfully obtained the aptamer named AF-3 which could recognize the lomefloxacin with high affinity (KD=(17. 57±0. 5) nmol/L). This screening method based on MNPs@PDAs makes it a promising reagent in the efficient aptamers selection of other targets.