Preparation Of Chitosan Oligosaccharides/Bacterial Cellulose And Evaluation Of Its Biocompatibility In Vitro

Bacterial cellulose (BC) is a bacterial synthetic polymer materials. Because of its three dimensional nano network structure, good biocompatibility, mechanical stability and plasticity properties, it has been widely used in food, textile fibers, high strength paper, artificial skin, artificial skin and the treatment of skin damage. However, high degree of crystallinity, insolubility, poor processability, and lack of functional groups restrain the bacteriostatic performance and the moisture retention, causing bacterial cellulose of limited further application. The chitosan oligosaccharide (COS) has good bacteriostatic performance and moisture retention. This thesis is aimed at biological modification of bacterial cellulose by adding COS, and study on the physical properties and biocompatibility as wound dressing.To determine the viable number of xylinum under static culture by MTT assay, a rapid detection of growth and reproduction xylinum method was explored in this study, laying the foundation for the COS modified BC. Modified BC films were synthesized by biological method, and obtained by freeze-drying. The porosity and dry weight of them were tested. Then, they were characterized by infrared spectroscopy (IR) and scanning electron microscope (SEM). Analyzing COS by GFC was to confirm that whether it was broken down and degenerated or not in the process of cultivation in remaining medium. This thesis is aimed at preliminary researches on biocompatibility of BC1, BC2and BC3by means of cytotoxicity test, inhibiting bacteria test and clotting time measurement.The result showed that by MTT method for the detection of Acetobacter xylinum growth cycle experiment, the vigor of acetobacter xylinum of the fourth days in culture was the best. Through the BC0, BC1, BC2and BC3structure observation and determination of yield, permeability, and water absorption of chitosan oligosaccharide, bacterial cellulose was modified by COS, with increasing COS, chitosan oligosaccharide-bacteria cellulose sponge yield decreased continuously, mesh decreased and then increased. Furthermore, the permeability and the water absorption of chitosan oligosaccharide-bacteria cellulose sponge increased first and then decreased. The remaining culture medium of the GFC display that the molecular weight of COS during bacterial cellulose synthesis was not changed, which also showed that the COS was not degraded and decomposed. Results of cytotoxicity test showed that BC1, BC2and BC3were not only non-toxic, but also promote the growth of cells. In addition, inhibiting bacteria test showed that they were antibacterial to Staphylococcus aureus and Pseudomonas aeruginosa, and antibacterial effects of them were stronger to Staphylococcus aureus than to Pseudomonas aeruginosa, especially that of BC2. Moreover, that anticoagulant effect of BCo was better than that of BC1, BC2and BC3, exhibited by clotting time measurements. That was to say, BC1, BC2and BC3were coagulative, so they were partly able to be used to be wound dressings. To sum up, three kinds of modified bacterial cellulose sponge (BC1, BC2, BC3), were synthesized by COS biological modifying. Bacterial cellulose COS improved the antibacterial and water holding capacity. Different amounts of COS caused bacterial cellulose with different physical properties and biocompatibility. COS-bacteria cellulose sponge was non-toxic to fiber cells, promoted cell growth, which contributes to the promotion of wound healing. The physical properties and biocompatibility of BC2is the most outstanding, showing great potential in application as the wound dressing.