Magnetic Poly(N-propargylacrylamide) Microspheres: Preparation by Precipitation Polymerization and Use in Model Click Reactions

Magnetic poly(N-propargylacrylamide) (PPRAAm) microspheres were prepared by the precipitation polymerization of N-propargylacrylamide (PRAAm) in a toluene/propan-2-ol medium in the presence of magnetic nanoparticles (oleic acid-coated Fe3O4). The effects of several polymerization parameters, including the polarity of the medium, polymerization temperature, the concentration of monomer, and the amount of magnetite (Fe3O4) in the polymerization feed, were examined. The microspheres were characterized in terms of their morphology, size, particle-size distribution, and iron content using transmission and scanning electron microscopies (TEM and SEM) and atomic absorption spectroscopy (AAS). A medium polarity was identified in which magnetic particles with a narrow size distribution were formed. As expected, oleic acid-coated Fe3O4 nanoparticles contributed to the stabilization of the polymerized magnetic microspheres. Alkyne groups in magnetic PPRAAm microspheres were detected by infrared spectroscopy. Magnetic PPRAAm microspheres were successfully used as the anchor to enable a click reaction with an azido-end-functionalized model peptide (radiolabeled azidopentanoyl-GGGRGDSGGGY(I-125)-NH2) and 4-azidophenylalanine using a Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition reaction in water. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4820-4829, 2011