Preparation and characterization of monodisperse molecularly imprinted polymer microspheres by precipitation polymerization for kaempferol

Abstract

A new kind of molecularly imprinted polymer (MIP) microspheres for the selective extraction of kaempferol was prepared by precipitation polymerization using 4-vinylpridine (4-VP) and ethylene glycol dimethacrylate (EDMA) as functional monomer and cross-linker respectively. The synthesis conditions, such as ratios of 4-VP/EDMA and polymerization time were discussed in detail. Results showed that the 2% was the optimal concentration of co-monomers to obtain monodisperse MIP microspheres, the best ratio of 4-VP/EDMA was 1:2, and 24 h was considered as the proper polymerization time. Compared with the MIP agglomeration or coagulum particles, monodisperse MIP microspheres showed the better adsorption capacity: the saturated adsorption capacity of monodisperse MIP microspheres was 7.47 mg g−1, the adsorption equilibrium could be obtained in 30 min. Finally, the adsorption performances of the optimal MIP microspheres were evaluated by kinetic adsorption, adsorption isotherm, and selective adsorption experiments, which indicated that the adsorption mechanism were chemical single layer adsorption and the separation factor was up to 3.91 by comparing with the structure similar compound (quercetin). The MIP microspheres exhibit prospects in the kaempferol efficient and selective separation.

Effect of Formulation on the Binding Efficiency and Selectivity of Precipitation Molecularly Imprinted Polymers

“…Similarly, lowering the amount of MAA, to MAA:TRIM = 1:2.3, also gave a similar effect attributed to insufficient concentration of the T-fM complex formed during association stage [ 24 ]. Similar results were obtained by Xia et al [ 25 ] who observed a decrease in the number of binding sites in the kaempferol imprinted microspheres with increasing ratios of MAA:EGDMA from 1:2 to 2:1. Both groups have concluded that there should be a balance between the concentration of cross-linker, which provides the rigidity of the microspheres, and the functional monomer, which dictates the amount of T:fM complexes formed, to be able to optimise the fM:X feed ratio for a particular system [ 26 ].…”

“…Both groups have concluded that there should be a balance between the concentration of cross-linker, which provides the rigidity of the microspheres, and the functional monomer, which dictates the amount of T:fM complexes formed, to be able to optimise the fM:X feed ratio for a particular system [ 26 ]. The most binding efficient MIP microspheres according to published results are the polymers synthesized in fM:X between 1:4–1:6 [ 25 ].…”

The Use of Aptamers and Molecularly Imprinted Polymers in Biosensors for Environmental Monitoring: A Tale of Two Receptors

“…These monoliths were then grounded up into smaller particles and packed into the column. Subsequent methods for imprinting MIP based nanoparticles and nanomaterials have gained prominence and allowed for small nano-sized MIPs with good yields and controllable sizes, such as solid-phase synthesis, emulsion, and precipitation polymerization [16][17][18]. For larger targets, epitope imprinting has shown promise as a viable way to imprint larger templates [19].…”

Microsphere Polymers in Molecular Imprinting: Current and Future Perspectives

“…The microspheres can be readily obtained through centrifugation [ 40 ]. In precipitation polymerisation, the morphology of the polymer is not significantly affected by the presence or absence of a template [ 6 , 52 , 122 ], but this has an impact on particle growth [ 70 ].…”