“Ferrite Route” Preparation of Iron Nanoparticles and Their Encapsulation in Styrene-GMA Co-Polymer for Biomedical Applications

The novel "ferrite route" was developed for synthesis of iron nanoparticles. Precursor Fe₃O_4+delta nanoparticles were synthesized by coprecipitation oxidation from aqueous solutions of xFeCl₂ +(1-x)/FeCl₃ (0lesxles1), which were reduced by hydrazine at 90degC. Under optimum conditions of x=0.66, the iron nanoparticles were 15plusmn3.7 nm in diameter and had a saturation magnetization of 110 emu/g. The nanoparticle yield was ca. 5 g/experiment, which is about ten times better than the ca. 0.4 g/experiment produced by the polyol-reduction method. Mini-emulsion copolymerization was used to encapsulate the iron nanoparticles in a copolymer of polystyrene and poly-glycidyl methacrylate that exhibits minimal nonspecific protein adsorption, thus suppressing biomolecular contamination. The polymer-coated iron beads were 80-120 nm in diameter and had a saturation magnetization of 51 emu/g, which is a value close to the 60 emu/g obtained when the core iron nanoparticles were synthesized by our previous polyol-reduction method