Synthesis And Properties Of Poly(2-methacryloyloxyethyl Phosphorylcholine)-coated Superparamagnetic Nanoparticles

Because of low toxicity and unique magnetic property,superparamagnetic iron oxide nanoparticles(SPIONs)have been widely used for various biomedical applications,such as magnetic resonance imaging(MRI),targeted delivery of drugs or genes,cell or protein separation and in hyperthermia.However,multiple challenges exist in the applications of SPIONs including biocompatibility,dispersability in physiological media and controllable uptake into cells.To solve these problems,we designed PMPC-coated SPIONs and investigated the impact of modification methods and structure of PMPC on the stability.First,poly(methylmethacrylate)-poly(2-methacryloyloxyethyl phosphorylcholine)block copolymer(PMMA-b-PMPC)-coated SPIONs was synthesized by“grafting from”method.RGD peptide was then conjugated to SPIONs by azidation and click chemistry.The structure of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy(~1H NMR)and fourier transform-infrared spectroscopy(FT-IR).Sphere structure of PMMA-b-PMPC-coated SPIONs was observed by transmission electron microscope(TEM)with the average size of 29.4 nm,which was consistent with that of Zetasizer.After hydrazinolysis of PMMA,hydrazide groups were generated on the brush of polymers,which enable labeling of fluorescence probe.PMPC-coated SPIONs was then synthesized by“grafting to”method.RGD peptide was conjugated to PMPC-coated SPIONs by means of PEG as the spacer.Narrow size distributions and average hydrodynamic size of 32.5 nm were obtained by Zetasizer,which was slightly larger than that of TEM.It has been demonstrated that SPIONs synthesized by both the“grafting from”and“grafting to”method exhibited great stability in physiological media and different pH.All these results demonstrated that the PMPC-coated SPIONs were attractive candidates for drug delivery system and cell or protein separation.