Studies On Chitosan And Its Derivative Nanoparticles

Chitosan with plenty of amino groups was the unique alkaline polysaccharide that existed in nature, it was one kind of the biomaterials with widely application prospect. In order to enhance its antitummor activity, chemically modified chitosan derivatives were prepared. Chitosan/thiolated chitosan nanoparticles with different molecular weights were also manufactured.Natural chitosan (Mw 820,000) was degraded by sodium nitrite with different concentrations, the viscosity average molecular weights of the products were 120,000,57,000 and 26,000, separately. The basic properties of the products such as solubility, degree of deacetylation, and so forth were also tested. Chitosan, mercaptoacetic acid and norcantharidin (NCTD) as materials, thiolated chitosan was synthesized mediated by p-toluene sulfonic acid and N-hydroxysuccinimide, norcantharidin chitosan derivative was also prepared with acetic acid-pyridine systems.Thiol content was measured by Ellman’s reagent, iodometric titration, modified iodometric titration and 4,4’-dithiodipyridine (DTDP), respectively, and DTDP was the optimum method for the determination of sulfhydryl content of thiolated chitosan. The oxidation-reduction process of thiol-disulfide was researched. Disulfide bonds was less completely reduced by cysteine than sodium borohydride, meanwhile the order of oxide ability of thiol groups was hydrogen peroxide, nature placement for a long time and probe ultrasonic for a short term.Chitosan/thiolated chitosan nanoparticles with different molecular weights were prepared by iron crosslinked method. Particle size and appearance of nanoparticles as evaluation index, the merit formula was selected as follows, the concentration of chitosan was 2.0 mg/mL, pH value of thiolated chitosan solution was changed to 4, TPP was 1.0 mg/mL, and TPP was added slowly with rapid stirring at room temperature. Particle size decreased with lower macromolecular weight and sulfhydrylation of chitosan. Covalent crosslinking nanoparticles were prepared, meanwhile the effect of probe ultrasonic and hydrogen peroxide oxidation on diameter and sulfhydryl content of thiolated chitosan nanoparticles were researched. Norcantharidin chitosan/thiolated chitosan derivative nanoparticles were also prepared, with the particle sizes of 204 nm and 210 nm, respectivelyElectron microscopy image indicated that nanoparticles were spherical shape. Zeta potentials of chitosan, thiolated chitosan nanoparticles were 29.82 and 23.55 mv, separately. The dilute stability of thiolated chitosan nanoparticles after probe ultrasonic and hydrogen peroxide was fairly well. The stability of thiol groups was decreased with the rise of pH values.The hemolysis and vascular stimulation effects of chitosan derivatives were much lower than that of norcantharidin, which indicated that the newly synthesized derivatives were more safety. There was no remarkably difference between high dose norcantharidin chitosan derivative and positive control drug 5-fluorouracil about antitumor effect, while the number of white blood cells of the derivative was increased significantly.