Molecularly imprinted superparamagnetic iron oxide nanoparticles for rapid enrichment and separation of cholesterol

Abstract

A general protocol to prepare surface molecularly imprinted polymer core–shell superparamagnetic Fe₃O₄ nanoparticles (Fe₃O₄@MIP SPNPs), using a surface-mediated RAFT polymerization approach, is described. Cholesterol-imprinted Fe₃O₄@MIP SPNPs were obtained by oleic acid-stabilized Fe₃O₄ nanoparticles with a trithiocarbonate agent and subsequently by polymerizing thin molecularly imprinted layers composed of dimethylacrylamide and N,N′-methylene(bis)acrylamide units. The surface-mediated RAFT polymerization approach allows the synthesis of ∼20 nm hybrid composite particles with a ∼6 nm MIP shell, exhibiting superparamagnetic properties (saturation magnetization = 35.4 emu g⁻¹) and specific molecular recognition of cholesterol. The Fe₃O₄@MIP SPNPs show the capability of rapid enriching and separating cholesterol (∼3.1% in weight) and are renewable and cyclically exploited due to their monodispersive and superparamagnetic features. Moreover, under optimal conditions, the Fe₃O₄@MIP SPNP recoveries of spiked human serum, milk, yolk and beef were 91.6%, 93.6%, 92.4% and 91.2%, respectively. Finally, the method of molecular imprinting on superparamagnetic particles can be extended to a wide range of applications for cell sorting, biomolecule enrichment and separation, and drug delivery.