Glycan-Imprinted Magnetic Nanoparticle-Based SELEX for Efficient Screening of Glycoprotein-Binding Aptamers

Nucleic acid aptamers, as useful alternatives of antibodies, have found a large range of promising applications such as affinity separation and bioassays. The screening of aptamers is critical for their applications. Aptamers are often screened by an in vitro methodology called SELEX (systematic evolution of ligands by exponential enrichment). Although numerous SELEX methods have been established to facilitate the selection, new efficient selection methods are still much needed. Molecularly imprinted polymers, which are antibody alternatives at the material level and competitors of aptamers, have not been used as a platform for aptamer selection yet so far. In this study, a glycan-imprinted magnetic nanoparticles (MNPs)-based SELEX was developed to efficiently screen aptamers against glycoproteins. Glycan-imprinted MNPs were used as an affinity interface to bind target glycoprotein, and then the target glycoprotein-bound MNPs were used as an affinity substrate for aptamer selection. The glycan-imprinted MNPs were synthesized by a state-of-the-art imprinting approach called boronate affinity controllable oriented surface imprinting. The glycan-imprinted MNPs exhibited high affinity and specificity and therefore allowed preferential binding toward target glycoproteins while excluding unwanted species. Two representative glycoproteins, including RNase B and transferrin, were employed as target glycoproteins, and aptamers with high affinity and specificity toward the two target glycoproteins were screened out in 3 rounds. This method exhibited some merits, such as high affinity, fast speed, and avoiding negative screening. Therefore, the glycan-imprinted MNP-based SELEX approach holds great values for the efficient screening of high-performance aptamers.