Synthesis and Characterization of Surface Grafted Poly(N-isopropylacrylamide) and Poly(Carboxylic Acid)- Iron Particles via Atom Transfer Radical Polymerization for Biomedical Applications.

This research relates to the preparation and characterization of surface grafted poly(N-isopropylacrylamide) and poly(carboxylic acid)-micron-size iron particles via atom transfer radical polymerization (ATRP). The surface grafted polymers-iron particles result in multifunctional materials which can be used in biomedical applications. The functionalities consist of cell targeting, imaging, drug delivery, and immunological response. The multifunctional materials are synthesized in two steps. First, surface grafting is used to place polymer molecules on the iron particles surface. The second step, is conjugation of the bio-molecules onto the polymer backbone. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy were used to confirm the presence of polymers on the iron particles. The thickness of the grafted polymers and glass transition temperature of the surface grafted polymers were determined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The covalent bond between grafted polymers and iron particles caused higher glass transition temperature as compared with non-grafted polymers. The ability to target the bio-molecule and provide fluorescent imaging was simulated by conjugation of rat immunoglobulin and fluorescein isothiocyanate (FITC) labeled anti-rat. The fluorescence intensity was determined using flow cytometry and conjugated IgG-FITC anti-rat on iron particles which was imaged using a fluorescence microscopy.