Preparation and recognition characteristics of alanine surface molecularly imprinted polymers

Abstract

Surface molecularly imprinted polymers (SMIPs) with high performance in selectively recognizing alanine (Ala) were prepared using a facile surface molecular-imprinting technique. The Ala SMIPs were prepared by heating suspension polymerization with methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker on vinyl-SiO₂ surface. The obtained materials were characterized using transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The synthesis conditions for the SMIP formation were systematically investigated to obtain the highest selectivity and binding capacity. The formation and monodispersity of the SMIPs are mainly affected by the molar ratio of the template, the functional monomer, and compositions of the cross-linker and solvent. In comparison to imprinted polymers prepared using traditional polymerizations, the obtained SMIPs exhibited a regular spherical shape and were relatively monodispersed. The template recognition properties were evaluated; the results showed that the maximal sorption capacity (Q_max) of the resulting SMIPs was up to 831 μmol g⁻¹, whereas that of non-imprinted polymers was only 341 μmol g⁻¹. A kinetic binding study showed that the sorption capacity reached 49.73% of Q_max in 30 min and sorption equilibrium at 60 min. The SMIPs have excellent accessibility and affinity toward Ala because the selectivity coefficients of SMIPs for Ala with respect to Gly, His, Glu and Phe were 2.36, 1.79, 2.48, and 2.56, respectively. The regeneration process verified that the SMIPs have admirably stable adsorption capacity toward Ala and can be regenerated up to eight times.