Molecularly imprinted nanoparticles prepared by core-shell emulsion polymerization

Submicron core-shell polymer particles, with molecularly imprinted shells, were prepared by a two-stage polymerization process. Particles of this type, prepared with a cholesterol-imprinted ethyleneglycol dimethacrylate shell and in the absence of porogen, were found to be 76 nm in diameter with a surface area of 82 m2 g−1. Cholesterol uptake from a 1 mM solution in isohexane was measured at both 10 and 30 mg mL−1, with the imprinted polymer showing considerable binding (up to 57%). Imprinted but not hydrolyzed and hydrolyzed nonimprinted polymers showed very low uptakes (≤4.5%) and a phenol-imprinted polymer showed reduced binding (36%) under the same conditions. Imprinted shells were also prepared over superparamagnetic polymer cores and over magnetite ferrocolloid alone. The cholesterol binding to magnetic particles was very similar to that of equivalent nonmagnetic materials. Magnetic particles could be sedimented in as little as 30 s in a magnetic field.