Abstract: In recent times, as nonviral gene vectors, chitosan and its derivations have attracted many researchers’ attentions. The preparation of a novel gene vector-magnetic nanoparticle coated with a novel polymer-lysine modified chitosan (CTS-lys) is described in this article. Initially, the correlation conditions of preparing CTS-lys were optimized, and it was demonstrated that lots of amines of chitosan were modified by lysine, which was indicated by infrared spectroscopy (IR) and proton nuclear magnetic resonance (1H-NMR). Subsequently, through the coprecipitation method, the lysine modified chitosan magnetic nanospheres (CTS-lys-MNPs) were attained. The characterizations of nanospheres were measured by transmission electron microscopy (TEM), dynamic laser light scattering, vibrating samples magnetometer (VSM), and X-ray diffraction (XRD). The cytotoxicity of CTS-lys-MNPs was also investigated with U293 cells. The results indicated that the average size of nanospheres was about 100 nm, and they had narrower size distribution, good superparamagnetic property, and perfect crystallinity, and they also retained low toxicity. Additionally, the combination of DNA and CTS-lys-MNPs was observed via agarose gel electrophoresis, and the ability of complexes ofCTS-lys-MNPs andDNAcrossingblood-brain barrier (BBB) in ratswas studied by single photon emission computed tomography (SPECT). The results showed that the gene vector was a superior material, which had the ability of targeting and avoiding the caption of BBB.

Key words: Chitosan, Lysine, Magnetic nanospheres, Target, Gene vector, Blood-brain barrier