Effect of carboxyl density at the core-shell interface of surface-imprinted magnetic trilayer microspheres on recognition properties of proteins

A novel protein surface-imprinted magnetic trilayer composite microsphere (Fe₃O₄@HEA@protein-MIPs) was designed and prepared. The objective of this study was to study the effect of carboxyl density at the core-shell interface on recognition performance. The imprinting process was carried out on the surface of Fe₃O₄@hydroxyethyl acrylate (Fe₃O₄@HEA) microsphere modified by maleic anhydride (MAH) in the presence of functional monomer acrylamide (AM) and cross-linker N,N'-methylenebisacrylamide (MBA). The results revealed that the adsorption rate, adsorption capacity and recognition capacity of surface-imprinted magnetic microsphere increased with increasing carboxyl density. Meanwhile, the increase of carboxyl density was conducive to improve the imprinting efficiency of the proteins with high isoelectric point (pI > 7). Furthermore, the effect of carboxyl at the core-shell interface on imprinting efficiency was restricted by the thickness of imprinted layer, and the critical thickness which related to the size of template protein was obtained by experiments.