Adsorbent, Antibacterial, Antitumor Activities Of Polysaccharid Nanoparticles And Approach To The Mechanism

Chitin/chitosan is one of the most important marine polysaccharides. Chitin and chitosan have attracted most attention in the world due to their good biocompatibility, degradability, low toxic and special physicochemical properties and biological activities. They have prospective applications in many fields such as biomedicine, chemical industry, light industry, and agriculture. The research on theory and application of chitin/chitosan will have great effect on the development of glycobiology, glycotechnology, and marine drug. With spring up of nanotechnology, nanoparticles and nanomaterials have been broadly applied in biomedicine and pharmacy more and more. Research on the application of chitosan nanoparticles in drug controlled delivery, targeted drugs and gene carrier will provide novel orientation for development of marine glycotechnology drug.In this paper, the importance of research on chitin/chitosan was first set forth from development of glycobiology, glycotechnology, and marine drug. Then chitin/chitosan chemistry and the application of nanoparticles in medicine were summarized in detail. At last, the research focusing on the biological activities of chitosan nanoparticles were reported. Chitosan nanoparticles were first synthesized by ion crosslinking, the conditions for synthesis of nanoparticles were optimized. Moreover, the lead sorption, antibacterial and antitumor activities of chitosan nanoparticles were first reported in this paper. The main contents are as follows:1. Characterization of chitosan nanoparticles. The physicochemical properties ofchitosan nanoparticles were characterized by TEM, SEM, AFM, Zetasizer, FTIR and XRD in detail. It showed that series of chitosan nanoparticles exhibited different surface morphology and array forms under various conditions. Chitosan nanoparticles are characteristic of little particle size, narrow size distribution and high zeta potential. FTIR and XRD analysis showed that the polyphosphoric groups and copper ions were introduced into the chemical structure of chitosan. Chitosan nanoparticles comprised a dense network structure of interpenetrating polymer chains crosslinked to each other.2. The sorption capacity and sorption isotherms of chitosan nanoparticles for lead ions were studied. Factors such as initial concentration of lead ions, sorbent amount, temperature, sorbent size, agitation period and pH value of solution that influence sorption capacity were investigated. It is found that chitosan nanoparticles could sorb lead ions effectively, the sorption rate was affected significantly by initial concentrations of solutions, sorbent amount, size, agitation speed and pH value of solution. The maximum capacity of lead sorption deduced from the use of Langmuir isotherm equation was 398 mg/g. The experimental data of lead ions sorption equilibrium correlated well with the Langmuir isotherm equation. New sorption sites were provided by introducing phosphoric groups, and the freeze-drying procedure led to the low crystallinity of chitosan nanoparticles, as a result, the sorption capacity was improved greatly.3. Antibacterial activity of chitosan nanoparticles. The antibacterial activity of chitosan nanoparticles and copper-loaded nanoparticles against E.coli, S.choleraesuis, S.typhimurium and S.aureus was evaluated by calculation of minimum inhibitoryconcentration (MIC) and minimum bactericidal concentration (MBC). Results show that chitosan nanoparticles and copper-loaded nanoparticles could inhibit the growth of various bacteria tested. Their MIC values were less than 0.25 u g/mL and the MBC values of nanoparticles reached 1 u g/mL. Atomic force microscopy revealed that the exposure of S.chloleraesuis to the chitosan nanoparticles led to the disruption of cell membranes and the leakage of cytoplasm. Chitosan nanoparticles provide higher affinity with bacteria cells for a quantum-size effect. Chitosan nanoparticles could be tightly adsorbed onto the surface of the bacteria cells so as to disrupt the membrane, which would lead to the leakage of intracellular components, thus killing the bacteria cells. On the other side, chitosan nanoparticles couldn't inhibit the growth of Lactobacillus and Bifidobacteria, which indicated the selectively antibacterial activity of chitosan nanoparticles. It is anticipated that chitosan nanoparticles could be applied broadly as antimicrobial agents in medicine for their high antibacterial activity and acceptable biocompatibilities.4. Preparation and antitumor activity of targeted chitosan nanoparticles. Chitosan nanoparticles exhibiting targeted antitumor activities were first prepared based on the unique character of cell membrane. The antitumor activities of chitosan nanoparticles were reported in vitro and in vivo, the involved mechanisms were investigated. The biocompatibilities and security of chitosan nanoparticles were assessed. Results showed that chitosan nanoparticles could effectively inhibit the growth of various human tumor cell lines cultured in vitro such as gastric cancer, intestinal cancer, liver cancer, lung cancer, bladder cancer, ovary cancer, pancreas cancer, kidney cancer andothers human carcinoma. The least IC50 value was 5.3 ug/mL. After treatment with chitosan nanoparticles, the typical necrotic cell morphology was observed by electron microscopy, a typical DNA degradation associated with necrosis was determined by DNA agarose electrophoresis. The zeta potential of cancer cell membrane could be neutralized by chitosan nanoparticles indicated by Zetasizer analysis. Flow cytometry showed the loss of mitochondrial membrane potential and occurrence of apoptosis in chitosan nanoparticles-treated cells. Gas chromatogram showed that the unsaturated fatty acid (C18:l, C18:2, C20:4) content of MGC803 cell membrane decreased greatly as 24.6%, 12.4%, 24% compared with normal control. Chitosan nanoparticles by intravenous injection, intraperitoneal injection and oral administration could inhibit the proliferation of human gastric cancer MGC803 (inhibitory rate: 69%, 78%, 79%) in nude mice. Administration dose and particle size of CNP make a great effect on its antitumor activity in vivo. Tumor inhibitory rates of CNP with various dose ranging from 3 mg/kg.W to 9 mg/kg.W are separately 48%, 52%, 53%, while those of CNP with different particle size as 35, 70, 100 nm are 62%, 59%, 35% respectively. Tumor tissues turned pathological necrosis shown by microscope and electron microscopy, on the other hand, CNP showed no notable side effects on growth of nude mice, and could improve the ultrastructure of live tissues of nude mice. Furthermore, CNP exhibit no notable effects on the growth of normal cells, and show the character without hemolysis, anaphylactoid and others side effects, therefore, CNP is a kind of promise material for antitumor drugs.