Preparation and properties of S-Naproxen molecularly imprinted polymer based on chiral functional monomer

In this study, 18 kinds of imprinted polymers (MIP_1～18) and corresponding non-imprinted polymers (NIP_1～18) were prepared by using S-2-mercaptopropionic acid as chiral functional monomer, S-naproxen (S-Npx) as template molecule. Experimental results show that the optimal imprinted polymers were prepared by nano-silica (Nano-SiO₂) as carrier, surface imprinting technique, the molar ratio of template molecule, functional monomer and crosslinker was 1∶4∶20, and methanol was used as porogen solvent. The adsorption behavior was studied by Langmuir and Freundlich adsorption isotherm models. The results show that the adsorption process was mainly based on multimolecular layer adsorption. Scatchard analysis shows that the maximum apparent binding capacity Q_max of the dissociation constant K_d was 0.82 mmol/L, Q_max was 9.92 mg/g. The kinetic study shows that when the adsorption equilibrium is reached, the maximum adsorption capacity can reach 5.73 mg/g, imprinting factor of 4.82, and the adsorption process accords with the quasi-second-order kinetic model. The structure of the optimal polymer MIP₃ and the corresponding NIP₃ was characterized by the scanning electron microscope (SEM). Also, the chiral resolution of MIP₃ racemic R, S-naproxen (R, S-Npx) was studied. Finally, MIP₃ was studied with HPLC, which reflected the mixed naproxen was separated successfully. The resolution factor reached 2.31 which proved that the resolution ability was well.