Preparation And Application Of Magnetic Chitosan Composites

Chitosan is a naturally degradable biopolymer. Magnetic materials have especial separability, and can transfer into the mechanical stress or thermal energy in the extra magnetic field. This study focused on the preparation and analysis of magnetic chitosan composites such as microsphere, membrane and rod.1. Magnetic chitosan porous microsphere and membraneThe magnetic chitosan porous composites were fabricated through porogenous-leaching technique. Magnetic particles and silica gel were mixed with acidic chitosan solution, the microspheres were prepared in high voltage electrostatic field, and then dissolved the silica particles by immersing the microspheres into hot alkaline solution. XRD, FT-IR, TG, SEM, Optical microscope, UV-vis spectrophotometer were used to investigate the phase, appearance and properties of the microsphere. The SEM and OM images showed particle size was about 0.6mm, and the microsphere has high porosity, good interconnected pores whose size was about 50μm.The adsorption kinetics and thermodynamics, other influencing factors were investigated by UV-vis spectrophotometer. In conclusion, methyl orange which is a diazoic dye bearing one sulfonic group, is efficient adsorbed on this microsphere, and the protonation of chitosan may expand the electrostatic attraction of this anionic dye. The saturated sorption capacity achieved 397.6mg/g, and sorption ratio attained 94.56%.The sorption of the microsphere for methyl orange displayed a complex process owing to the exchange between monolayer adsorption and multilayer adsorption.The porous membranes were prepared by casting precursory solution that was the same with preparing microsphere, removing the solvent by evaporation, and dissolving the silica particles by immersing the membranes into hot alkaline solutions. The porous volumes are above 45%, the sorption capacity was 185.7mg/g, and sorption ratio attained 96.33% in the solution (pH=6.25).2. Magnetic chitosan three-dimensional compositesIn-situ compositing method was used to prepare magnetic chitosan rod by using chitosan membrane as template, when OH" migrated into the precursory solutionthrough the chitosan membrane, resulted in the aggradation of chitosan and X-ray diffraction analysis results demonstrated the formation of magnetite. The SEM micrograph showed the layer structure. From the TEM images, it can be concluded that the size of Fe₃O₄ particles was about 15nm, and dispersed homogeneously in chitosan matrix. The results of magnetic measurement showed the composites were super-paramagnetic, this is the especially of nano magnetite. Mechanical properties were measured, bending strength attained 98.8MPa which did not decline while compared with pure chitosan materials. Prepare the magnetite/ hydroxyapatite/ chitosan nano-composites by in-situ compositing method on the condition of preparing magnetic chitosan composites above. The mechanical properties of the material used in bone repair are significant. The bending strength achieved 118.5MPa when Fe₃O₄/HA/CS=7.5/7.5/85 (w/w/w), which were much better than that prepared via traditional method. In conclusion, all the characteristics of the composites suggested a potential application in tissue repair.