Origin of macromolecular crowding: Analysis of recognition mechanism of dual-template molecularly imprinted polymers by in silico prediction.

Multi-template imprinting is one of the challenge for molecular imprinting since the selectivity and binding affinity for each analyte decrease significantly compared with the corresponding molecularly imprinting polymers (MIPs) against single template. In this work, molecular crowding effect was tried to remedy the problem of imprinting reduction caused by the competition of two templates. Methacrylic acid (ACR) was used as functional monomer, ethylene dimethacrylate (EDMA) as crosslinker, and polystyrene (PS) as macromolecular crowding agent. With levofloxacin (S-OFX) as the first template, a number of compounds with varied chemical structure were chosen as the second template to investigate the imprinting effect of dual-template. When S-OFX and naproxen (S-NAP) was used as the dual-template, the imprinting factor (IF) of the resulting MIP for S-OFX was 20.1 and IF for S-NAP was 10.9. In contrast, for the single-template MIPs, IF for S-OFX was 22.4, and IF for S-NAP was 11.9. As a comparison, the IF of the DT-MIP prepared in absence of PS was only 2.3 for S-OFX and 1.0 for S-NAP. To analyze recognition mechanism of the molecular crowding-based imprinting system, molecular dynamics simulations to the chain structure of PS and binding modes between template and functional monomers was conducted by NAMD software. All the results displayed that molecular crowding is a promising method to improve the affinity of the dual-template imprinted polymer.

Supermacroporous polymer monolith prepared with polymeric porogens via viscoelastic phase separation for capillary electrochromatography.

Supermacroporous poly(methacrylic acid-butyl methacrylate-ethylene glycol dimethacrylate) monoliths with the pore size up to 5-10 µm were successfully prepared in a ternary polymeric porogens utilizing viscoelastic effect. High concentration (over 20 mg/mL) of polystyrene (PS) in porogen was used to achieve the desirable characteristics of the monolithic capillary. Modification of the co-porogen composition, i.e., the content of dimethyl sulfoxide and isooctane, enabled tailoring of the supermacropore structure with a wide range of pore size. The effects of the amount of polymer porogen and molecular weights of PS on the formation of supermacropore were also studied. In preliminary applications, the separations of alkyl phenones and alkylbenzenes were achieved on the supermacropore columns using a mode of capillary electrochromatography. The study demonstrated successfully the ability of polymer porogen to form supermacropore monolith via viscoelastic phase separation.