Preparation And Characterization Of Magnetic Chitosan Microspheres Used For Targeted-drug Carrier

The key to the magnetic targeted-drug which has become a hot research in the anti-cancer therapy was the preparation of magnetic carrier for drug, and whether it is superior or inferior can influence the performance of magnetic targetted-drug directly. In this work, the magnetic Fe₃O₄ nanoparticles with narrow size-distribution were prepared by chemical co-precipitation firstly, then the magnetic chitosan(CS) microspheres were prepared by a suspension cross-linking technique with the CS and magnetic Fe₃O₄ nanoparticles prepared in first step. The preparation condition for both products was optimized via single factor experiment and orthogonal experiment. The product was characterized by X-ray powder diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), dynamic laser scattering analyzer (DLS), FTIR spectrophotometer (FTIR), etc. As a result, the magnetic Fe₃O₄ nanoparticles prepared in first step are dispersive and have fine scrystal structure and narrow size-distribution mainly in the range of 5nm and 20nm, the average size achieve 11.7nm, it's found that the size-distribution were influenced seriously by dropping rate of ammonium hydroxide which should be controlled at 6-8 drop/min aptly; the prepared magnetic CS microshperes encapsulated the magnetic Fe₃O₄ nanoparticles successfully, the product with intact skeleton constructure and narrow size distribution is spherical, dispersive and the average size is about 10μm, though the surface presents concavo-convex and the hollows. The most important aspect for the magnetic carrier is a sufficient magnetic field intensity produced by least ferromagnets to excite all the dipole moments of each 0.05 g magnetic carrier 2 cm far away from the ferromagnets, so the relative magnetic response of the product in the magnetic field was also analysed and evaluated carefully. The relative magnetic response of magnetic Fe₃O₄ nanoparticles and magnetic CS microshperes was detected as 0.0837 g/ (2cm·0.05g magnetic powder) and 0.0472 g/(2 cm·0.05 g magnetic CS microspheres) respectively, and a 32.6 mT magnetic field which was produced by four ferromagnets was found to be sufficient to excite almost all of the dipole moments of 0.05 g composite magnetic microspheres 2 cm far away from the ferromagnets. In conclusion the magnetic CS microspheres obtained are qualified for the carriers in the targeted delivery of drugs and further clinical application.