Preparation, Characterization And Performance Analysis Of New Water - Soluble Chitosan

Chitosan is a important polysaccharide biopolymer due to its unique physicochemical property and biological function. However, these activities are limited to acidic conditions owing to its poor water solubility above p H 6.5. Currently, the modification of chitosan has become a hotspot in the biomaterial field worldwide.In this paper, we attempted to develop two ways to synthesize novel water-soluble chitosan derivatives,(1) We used N-hydroxy succinimide to activate quaternary phosphonium salt, and N-phosphonium chitosan(N-PCS) was prepared by reacting chitosan with activated quaternary phosphonium salt.(2) A novel betaine, which contained isocyanate terminal group, was synthesized through two steps of the classic chemical reaction using isophorone diisocyanate, N, N-dimethyl ethanolamine and 1, 3-propane sultone. Next, we obtained N-betaine chitosan(N-BCS) via the reaction between isocyanate and amino group. The products were characterized and confirmed by Fourier transform infrared spectroscopy(FTIR), nuclear magnetic resonance(NMR), X-ray photoelectron spectroscopy(XPS) and ultraviolet-visible spectrophotometry(UV-vis).Compared with chitosan, both N-QPCS and N-BCS can be dissolved in distilled water with various solubility values. And the water solubility increased with the increase of degree of substitution. That’s to say, the water solubility of our products were superior to chitosan.Plate count method was used to evaluate the antibacterial activity of N-QPCS and N-BCS. The results showed that our products exhibited higher antibacterial properties than chitosan against E. coli and S. aureus. When the concentration of N-QPCS was up to 250 μg/m L, the antibacterial ratio against E. coli and S. aureus were 90.0% and 86.0%, respectively. Therefore, the excellent antibacterial activity of N-QPCS was due to the synergetic antibacterial effect of quaternary phosphonium salt and chitosan. But antimicrobial activity was not observed on N-BCS. Owing to the introduction of betaine, a large number of amino group of chitosan were consumpted, which caused this phenomenon.In order to research the cytotoxicity of N-phosphonium chitosan and N-phosphonium chitosan on human skin fibroblasts cells, the effect of products on the survival rate of normal cell was evaluated by cell counting kit(CCK-8) quantitatively. It was found that the cell survival rate could be above 90% under the impact of N-QPCS 14 at the concentration of 250 μg/m L. Thus, N-QPCS were safety at the normal used concentration. And then, the cell survival rate was more than 90% after the cell contacted with N-BCS that the concentration was 750-2500 μg/m L. Compared with chitosan, the toxicity of N-BCS decreased obviously when the concentration reached 1000 μg/m L.