The Preparation And Drug Delivery Of Magnetic Poly(Lactic Acid) Microspheres

Along with the development of Biological Medicine, the target-specific and sustained-release drug delivery system becomes the hot-spot of research nowadays. Among those, the high molecular weight magnetic microsphere is one type of active-drug carrier which is long-lasting, target-specific, surface functional, and bio-compatible. Therefore, medical researchers have been paying more and more attention on it globally and its development has shown attractive prospect in the field of material sciences and biological medicine.A burst release which a large amount of drug will be released could occur among drug loaded polymer microsphere during the release of drug. The burst release can cause sharp increase of the drug concentration in blood hence induces toxic side-effects. Therefore, control of the burst release has been the project to which medical researchers pay effort. With the advantage of The surface modification of nano-/micro-particles is based on the advantage of layer-by-layer self-assembly technology, which is not restricted by the size and shape of base material. In this essay, the Fe3O4 magnetic nanoparticles are introduced into the drag delivery poly(lactic acid) microspheres which are surface modified by the layer-by-layer self-assembly. In this case, the burst release of the drugs can be controlled by the multilayer's resistance. As a result, the drug-delivery magnetic microspheres which have drug release controlling function can be produced. Details are as follows:Firstly, the Fe3O4 magnetic nanoparticles were prepared by chemical co-precipitation process. Then, using Fe3O4 magnetic nanoparticles as the magnetic component and protein as the model drug, multiple emulsion method is applied in the production of magnetic poly(lactic acid) drug loaded microspheres. In order to effectively reduce the burst release of drugs of microspheres, layer-by-layer self-assembly technology was used to pack polycationic chitosan and polyanionic alginate in turn around the microsphere surface. In addition, glutaraldehyde was used as a crosslinking agent to solidify the microsphere. A further study concerning the vitro release properties of microspheres has been carried on in the end. The study compared the release behavior of poly(lactic acid) microspheres and microspheres which were covered by uncrosslinked and corsslinked multilayer on the surface. Experimental results shows that magnetic nanoparticles can be loaded effectively in poly(lactic acid) microspheres and crosslinked multilayer film can inhibit the burst release significantly therefore to control the release of drug effectively.