Enhanced adsorption performance of varying-length mRNA on Oligo dT affinity resins through optimal pore size and grafting

The enormous potential of mRNA-based therapeutics in vaccines and medicine has led to the consideration of various mRNA sizes, ranging from ~1000 to 10000 nucleotides (nt). However, the commonly used Oligo-deoxythymidine (Oligo dT) affinity resins are not initially designed for such a wide range of sizes, and present challenges in achieving optimal performance for the separation of a given mRNA. In this paper, two factors of the resin beads, pore size and grafting were focused. The effects of varying pore sizes, ranging from 150 to 850 nm, on both static and dynamic adsorption for varying-length mRNA (1000-8500 nt) were investigated. It was found that static adsorption capacity and uptake kinetics were correlated with the mRNA length. Interestingly, dynamic binding capacities (DBCs) showed an increase-then-decrease trend with increasing pore size. An optimal pore size of about 350 nm could lead to the highest DBCs for all tested mRNA. Additionally, the effects of polymer grafting on the adsorption performance were studied. The results revealed that polymer-grafted resin exhibited 24-55% higher DBCs than non-grafted resin. The enhanced DBCs could be attributed to the improved uptake rate facilitated by the polymer grafted. These investigations emphasize the importance of optimizing pore size and grafting for Oligo dT affinity resins, providing valuable guidance for selecting and designing new resins for different mRNA products.