The Study On A Novel Quaternized Chitosan Nano Delivrey System

In this study, a chitosan derivative N, N, N-trimethyl chitosan chloride (TMC) was synthesized by the reaction between methyl iodide and chitosan. Based on contrarily electrostatic interaction, two novel type of nanoparticles were formed, which are TMC/CMC or TMC/Hep nanoparticles.The forming condition, the size, polydispersity, zeta potential, morphology and the stability of the nanoparticles were measured with IR, dynamic laser scattering, transmission electron microscopy and atom force microscopy. It is found that the nanoparticles were global and the size was between 150-600 nm, the polydispersity was narrow, and mostly which were positive. The size and zeta potential of the nanoparticles were adjustable.As a carrier for the anticancer drug, doxorubicin (DOX), it was found that the size of the drug loaded nanoparticles was smaller than blank nanoparticles. The loading efficiency and the loading capacity of the nanoparticles were related with the concentration of TMC and the quaternization degree of TMC, and could be adjusted. And the drug released in vitro showed an initial fast release phase, followed by a platform time, and had a better fitting precision with first order elimination kinetics and Ritger-Pappas model.MTT assay was used to test the inhibited effect of the DOX loaded nanoparticles on HepG 2 cells. It was showed that they had a slightly decreased cytotoxicity to free DOX within 24h, while with time extended its toxicity reinforced. Animal study indicated that the half-time of DOX-loaded nanoparticles prolonged and the DOX concentration in the heart was decreased and increased in the liver.In order to observe the cell uptake of nanoparticles, we synthesized the TMC-g-FITC, and composed two novel nono-sized fluorescent probes: TMC-g-FITC/CMC and TMC-g-FITC/Hep nanoparticles. Uptake of the nanoparticles by HepG 2 cells was observed by inverted fluorescence microscope and confocal laser scanning microscopy. it was found that the nanoparticles had little toxic to the cells, the culture tempreture and the concentration of TMC-g-FITC affected the uptake process, and the fluorescence nanoparticles first aggregated across the cells and then be absorptive by the cell and cell nucleus. And the fluorescence nanoparticles were accumulated at liver after injected from mice tail vein.The pDNA loading, protecting and transfection capacity of TMC and its nanoparticles were evaluated, effective plasmid DNA carrier, it was discovered that both of them can protect the pDNA from being digested. 48h later after transfection, TMC12.11/pDNA nanoparticles has the highest transfection efficiency. However, to TMC/CMC/pDNA and TMC/Hep/pDNA nanoparticles, the time was 72h later.