Molecularly imprinted soluble nanogels as a peroxidase-like catalyst in the oxidation reaction of homovanillic acid under aqueous conditions

A novel type of soluble peroxidase-like imprinted nanogels incorporating hemin, acrylamide and 4-vinylpyridine as functional monomers was prepared by solution polymerization method. Such highly crosslinked nanogels could be conveniently separated from the reaction mixture through precipitation, ultracentrifugation or ultrafiltration, whereby they could be analyzed by gel permeation chromatography (GPC), transmission electron microscopy (TEM), dynamic light scattering (DLS) and environmental scanning electron microscope (ESEM). More importantly, the molecularly imprinted polymers (MIP) showed greater catalytic activity in DMSO–Tris–HCl buffer than in pure Tris–HCl buffer mainly because it could behave as a homogeneous catalyst under appropriate DMSO–Tris–HCl system. The results suggested that the unavoidably restrained transport properties inside conventional insoluble imprinted polymers might be overcome. Additionally, the MIP showed higher adsorption towards substrate under aqueous conditions compared with its corresponding blank polymer, which was due in part to its higher catalytic activity.