Synthesis and Characterization of Lysine Modified Chitosan Magnetic Microspheres: A Novel Gene Delivery System

This paper describes a new formulation of magnetic nanoparticles coated by a novel polymer lysine modified chitosan (CS-lys) as gene carrier. Lysine modified chitosan was synthesized by performing carboxyl of lysine and amido of chitosan in the presence of 1-Ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride (EDC). The absolute chemistry of the Lysine modified chitosan obtained were characterized using IR and ¹H NMR, respectively. The results indicated that many amines of chitosan were modificatied with lysine, and optimized the correlation conditions. The lysine modified chitosan magnetic microspheres were preprated by co-precipitation method. The characterizations of microspheres were measured by TEM, XPS, Dynamic Laser Light Scattering, Vibrating Samples Magnetometer, and X-ray diffraction. The resultes indicated the average particle size was about 100nm and have good superparamagnetic property. The cytotoxicity of CS-lys MNPs was investigated with U293 cells. The results showed that the CS-lys MNPs retained of low toxicity; additionally, combination of DNA and CS-lys MNPs was observed from agarose gel electrophoresis, suggesting that the CS-lys MNPs could be a novel magnetic targeting gene carrier. We also studied the ability of complexes of CS-lys MNPs and DNA crossing BBB in rats by single photon emission computed tomography (SPECT).