Drug delivery system is a method to transport the drug of the required amount accurately to the targeted diseased part. Recently, the concept of Magnetic Targeted Drug Delivery System (MTDDS), based upon magnetic particles under the action of an external magnetic field, exhibits considerable potential for a wide range of medical applications. Gene therapy is the insertion of genes into an individual's cells and tissues to treat diseases. As the recombinant virus vector has many limits and problems, more studies turn to the nonvirus vectors, which have transfection efficiency and low cytotoxicity. PLLA(poly(L lactic acid)) can be biodegradable and has high biocompatibility. PLLA is already used in functional biomedical materials, including functional gene vectors.

This thesis covers the synthesis and characterization of superparamagnetic iron oxide nanoparticles and summarizes the research process of polymeric coating as a function of gene vectors. Nuclear magnetic resonance technology is used to identify the structure of the polymer step by step. At last, the use of PLLA(poly(L lactic acid)) in gene therapy is combined with the MTDDS. The PEI-PLLA-SS-PLLA-PEI was successfully made and could be applied for fabrication of superparamagnetic iron oxide nanoparticles as polymeric coatings at nanometer scale.