Study On Preparation And Properties Of Silver Loaded Chitosan Based Electrospun Nanofiber Membrane

Chitosan (CS) is the only alkaline polysaccharide in the nature, and its non-toxicity, immunogenicity, broad-spectrum antibacterial activity and powerful blood coagulation function, good biological compatibility and biodegradable property make it an important medical material, which can help to promote wound healing and tissue repair regeneration.Chitosan based electrospun nanofiber has small fiber diameter, large specific surface area, high porosity as well as good biomedical properties from chitosan. The introduction of silver ion or silver nanoparticles can further enhance the antibacterial properties. The fibrous mat has potential medical prospects in the medical dressings field.Chitosan and polyethylene oxide (PEO) were chosen as raw polymer materials, with50%acetic acid or90%acetic acid as solvent, silver nitrate as the precursor, to prepare CS/PEO blend spinning solution and Ag-CS/PEO blend spinning solution separately, then electrospinning was carried out. Scanning electron microscopy (SEM) was used to observe and analyze the fibers morphology and diameter distribution. The influence of solution parameters (solution concentration, solvent concentration and CS/PEO weight ratio) and the process parameters (voltage, distance and flow speed) on fiber morphology were investigated to determine the blend spinning solution system and spinning process parameters. The research results showed that the solutions with CS/PEO weight ratio of75/25and90/10are spinnable, and the optimal spinning process conditions were as follows:90%acetic acid as solvent, concentration of spinning solution at4wt%, flow speed at0.5mL/h, distance at20cm, and spinning voltage at10kV.In this paper, silver nanoparticles containing Ag-CS/PEO solution were prepared in two ways, that is chitosan acting as reducer (solution prepared without UV irradiation) and ultraviolet reduction (solution prepared with UV irradiation). The resultant solution was determined with ultraviolet-visible spectral to investigate the existence form of silver in solution. The result showed that silver nanoparticles were successfully prepared in spinning solution, and that longer UV irradiation resulted in more silver nanoparticles. Solutions with or without UV reduction were electrospun to prepare silver loaded fibrous membrane. Energy dispersive spectroscopy (EDS) results showed that the silver element was successfully introduced into the nanofibers. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were applied to observe the morphology of fiber and silver particles embedded in the fiber, and the results showed that silver loaded fiber had smooth appearance. In fibers electrospun from solution without UV irradiation, silver nanoparticles with1-9nm in diameter, were evenly distributed. In fibers electrospun from solution with UV irradiation, silver nanoparticles with10-80nm in diameter, were poorly distributed. The composition and structure of the fiber were characterized by infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), and the results showed hydrogen bonding was formed between CS and PEO molecules, which improved the interaction between the molecules, resulting into better spinning performance of the solution. The introduction of silver almost didn’t change the FT-IR spectrum of the electrospun membrane.In addition, regarding the characteristics of medical dressings, this paper studied the mechanical property, water absorption and dissolution performance, as well as antibacterial property against staphylococcus aureus of CS/PEO nanofibers membranes with or without silver, respectively. Silver release property of membrane was studied in simulated body fluid. The research result showed that chitosan based nanofiber membranes showed certain mechanical strength, high water absorbability, and excellent antibacterial property. CS/PEO nanofibers membrane showed weaker antibacterial property, with the inhibition width within1mm. While, the inhibition width of silver loaded CS/PEO nanofibers membrane was more than5mm, which means the introduction of the silver significantly improved the antibacterial property. Silver release performance results showed that, silver in the fiber membrane was slowly released by dissolving mechanism, overcoming the burst release of ordinary medical dressings used in early stage. Two membranes can be used as the carrier of medical dressings, according to the different of the wound inflammation degree.