A Study On The Synthesis And Antibacterial Mechanism Of Water Soluble Chitosan Derivatives

In this paper, four chitosan derivatives were synthesized, and the structure, heat transition temperature, solubility and antibacterial activity were studied. The reaction conditions of O-CMCs and SCs were systematically investigated through orthogonal design, then the best conditions were found. The antibacterial mechanism of water soluble chitosan derivatives was discussed carefully. The effect of chitosan and derivatives on plasmid, gene expression and protein were studied from four influencing elements in vitro and in vivo.Results show that the antibacterial activity of O-CMCs, SCs, HECs and O-HACC were no weaker than that of chitosan, and at the same time the water solubility was increased greatly. The best reaction conditions were: O-CMCS: 0℃,chitosan vs chloroacetic acid was 3: 2.3(w:w),48h; SCs: 68℃, chitosan vs chlorosulfonic acid was 1: 4(ml:g), 4h.The important results of antibacterial mechanism were discovered. Chitosan and derivatives have a strong effect on the structure of plasmid and enzymatic activity. The influencing degree was increased as the concentration of chitosan increased. When Mw>20000, the influencing degree was no longer remarkable, while the degree was dropped with Mw when Mw<8000. Another conclusion was that time had no relationship with influencing degree. In the study of gene expression, we made Pseudomonas ND6 as experimental object, then we found that the degradation gene was almost lost completely. From the above we think chitosan and derivatives can restrain reproduction of bacteria through destroying the structure of DNA, preventing gene expression and making protein denaturalization.