Preparation Of Magnetic Chitosan (CS)-poly (Acrylic Acid) (PAA) Microspheres And Study On Their Immobilizing BSA

Chitosan(CS)-poly(acrylic acid )(PAA) suspension had been synthesized by graft polymerization of acrylic acid(AA) in chitosan solution. Then magnetic CS-PAA microspheres were prepared by the cross-linking of glutaraldehyde with the graft copolymer(CS-PAA) in the presence of polyethylene glycol(PEG) and magnetic fluid (Fe₃O₄). The physicochemical properties of the microspheres were investigated by using SEM, FT-IR, element analyzed instrument, TG, DSC, and magnetometry. The results demonstrate that the shape of the microspheres is spherical, and their sizes are smaller (100-400nm). The magnetic microspheres have good thermal stability at the temperature of below 135℃. The quantity of Fe is 2.47%. As far as their magnetization characteristic concern, their susceptibility is about 2.16×10^-4, and the best magnetic quality is around 1.30emu/g at 5KG magnetic field intensity. They are paramagnetic materials.The magnetic chitosan(CS)-poly(acrylic acid )(PAA) microspheres were loaded with Bovine Serum Albumin (BSA) as model drug by adsorption. The synthesis and adsorption conditions were investigated, and the adsorption kinetics was discussed. Then release studies were performed, and the influence elements such as pH, ion concentration and temperature were discussed. The best results show that the quantity of immobilization is over 400mg/g. The microspheres immobilizing BSA release scarcely in the simulated gastric condition. But the release rate has found to be 80.5% after 6h in the simulated intestinal pH condition. The magnetic chitosan(CS)-poly(acrylic acid )(PAA) microspheres is sensitive to the pH from 5.0 to 8.0.Because the magnetic chitosan(CS)-poly(acrylic acid )(PAA) microspheres are responsive to magnetic field and pH outside, they have good prospect to be used in the controlled release of medicine.