Fabrication And Performance Research Of Chitosan Nanofibers Contained With Silver Nanoparticles

Diabetes is a worldwide disease which covers an increasing number of people annually. It is particularly important to prepare a novel and effective wound dressing for patients with diabetes.The electrospun nanofiber membrane could become the best choice for such medical dressings owing to its excellent properties. Because there are many bacteria around the wound, so the preparation of wound dressing with effective antimicrobial properties is the key to the research. Both chitosan and silver nanoparticles have strong antibacterial effect, the combination of them can significantly increase the antibacterial effect. The preparation of the antibacterial chitosan nanofiber membrane contained with silver nanoparticles has a good guidance for the development of new wound dressings and wound healing process of diabetes ulcer.Using carboxymethyl chitosan as a reducing agent and stabilizer, with silver nitrate solution as precursor, silver nanoparticle solution was prepared successfully via an in situ reaction in solution.Silver nanoparticle solution was characterized by ultraviolet and transmission electron microscopy(TEM), the maximum absorption peak of UV can be detected at around 410 nm, which indicates the existence of silver nanoparticles. TEM results show that the particle size of silver nanoparticles is about 10 nm.We have tried different solvent systems for the preparation of electrospinning solution of chitosan in this study. And a final formulation with a large amount of deionized water and a small amount of DMSO, acetic acid and Triton X-100 mixed solvent was fixed as the electrospinning solvent system of chitosan, followed by the introduction of PEO with an ultra high molecular weight,the electrospinning process was carried out with an ambient temperature of 40-45 oC. The hybrid membranes of chitosan and PEO with the ratio of 90/10, 80/20 and 70/30 were prepared successfully.Deionized water in the mixed solvent system was replaced by the silver nanoparticle solution, othersolvent remains the same, and then the electrospinning process was carried out, the chitosan composite containing silver nanoparticles could be prepared. These scaffolds were characterized by SEM, TEM, FTIR, Porosity Testing, water absorption, Contact Angle, XRD, Mechanical Testing,antimicrobial, MTT, etc.The results show that the continuous chitosan nanofiber could be acquired after adding a small amount of high molecular weight of PEO. It could be noticed from the SEM images that there is a good morphology and random distribution for the nanofibers with an average fiber diameter of 100 nm to 200 nm.TEM showed that there is a random distribution for silver nanoparticles in Ag-CS/PEO(80/20)nanofibers. FTIR results showed that the chemical structure of CS and PEO blends did not change,but there is a strong interaction between the molecules. The cross-linking effect and the addition of silver nanoparticles can increase the intermolecular hydrogen bond. The porosity increasesd with the addition of CS. After adding silver nanoparticles, the porosity changed greatly. The change trends of moisture absorption properties of different nanofibers is consistent, the water absorption increased rapidly within two hours, and then increased slowly, the water absorption keeped balance after 24 hours. The addition of silver nanoparticles had almost no effect on water absorption. XRD results showed that the crystallinity of CS blends with PEO was significantly reduced. The mechanical results showed that the tensile strength of the scaffolds decreased with the increase of CS, but the scaffolds still can meet the requirements of the use of medical dressings.MTT results showed that chitosan composite nanofibers containing silver nanoparticles did not showed inhibitory effect on the growth of fibroblasts compared with the chitosan fiber without silver nanoparticles, and these nanofibers have good biocompatibility. Bacteriostatic test results showed that chitosan nanofibers containing silver nanoparticles had a very good inhibitory effect to escherichia coli and staphylococcus aureus, suggesting that chitosan nanofibers containing silver nanoparticles had great potential for the treatment of diabetes mellitus ulcerative wounds.