Prepartion And Characterization Of Typeâ…  Collagen Based Waterproof Nano Membrances For Wound Healing

type Ⅰ collagen continues to be the ideal material for biomedical devices given its low antigenicity, biocompatibility, promotion of cell attachment and growth collagen based nanofiber membrane manufactured by electrospinning not only has the nature of collagen, but also has properties such as large surface area, high porosity, three-dimensional structure and so no which can mimic the structural and biological properties of the extracellular matrix(ECM), as a result, electrospinning collagen nano fiber as wound healing material is a promising method in medical field. currently, The typical solvent of collagen electrospinning is 1,1,1,3,3,3hexafluoro-2-propanol(HEIP) because of its high volatility and polarity. Conversely, HEIP is a costly toxic solvents which is harmful to human and environment, what is more important, recent studies have proved that HEIP can disrupt collagen triple helical structure, which limit the use of HEIP as collagen elgectrospinning solvent in industry. In addition, the poor waterproof performance of collagen is another important factor that limit the application of collagen. Given the above, we explore into the bovine Achilles tendon typeⅠcollagen electrospinning solvent, electrospinning parameters and water resistance of the collagen fibers before and after electrospinning.In this paper, we investigate the influence of different solvents on the viscosity and thermal stability of collagen; then electrospinning experiment was carried out, the micromorphology of collagen fibers were investigated by a Scanning electron microscopy(SEM). The rsults shows that under the same concentration, the viscosity of the collagen solution formed by different solvents is different; collagen regenerated from fluorinated alcohols and organic acids have lower thermal stability and denaturation temperature; electrospun collagen solutions ranged in concentration from 2 % to 4 % of HEIP, and resulted in collagen fibers, while collagen solutions ranged concenteation between 5 % to 10 % of formic acid and aqueous acetic acid, is the most suitable concentration for electrospinning. Experiments also found that collagen solutions of acid and aqueous acetic acid exhibited poor fiber-forming properties which significantly improved by adding polyethylene oxide(PEO). The optimal spinning conditions resulted from orthogonal experiment were as follows: 80 %(v/v) acetic acid–deioized water mixture as solvent, total concentration was 7 %, m(collagen): m(PEO) was 90:10, applied voltage 25 Kv, tip-to-target distance at 20 cm and flow rate 0.8 mL/h. smooth and uniform fiber with diameters 245 ± 53 nm was formed under this condition.The physical and chemical properties of collagen nanofiber were investigated by Fouriertransform infrared spectra(FTIR), X-ray diffraction(XRD) and thermal analysis. infrared spectroscopy showed that the characteristic absorption bands of collagen and PEO did not significantly change, the triple helix structure of collagen still preserved judged by the ratio between 1452 cm-1 and 1233 cm-1 absorption peak intensity; hydrogen should exist between collagen and PEO, our hypothesis is that PEO is unfavorable for the preservation of triple helix structure. TG analysis showed that collagen nanofiber membrane exhibited thermal characteristics of collagen and PEO, Analysis of the TG curve of each material show that the mass fraction of collagen is 87% in collagen nanofiber membrane, which is approximate to the original content of collagen 90% in spinning solution. X-ray diffraction analysis showed that the molecular interaction collagen and PEO weaken the intermolecular force between collagen molecules, increased the distance between intermolecular chain and changed their crystallinity in some extent.collagen fiber membrane was cross-linked by 25% glutaraldehyde(GTA) aqueous solution to improve its water-resistant ability and mechanical properties. optimum crosslinking time was determined by immersion test, tensile mechanical analysis and static contact angle of water; The physical and chemical properties of cross-linked collagen nanofiber was investigated by Fouriertransform infrared spectra(FTIR), X-ray diffraction(XRD) and thermal analysis. The results show that water-resistant ability and mechanical properties of crosslinked collagen fiber membrane was both improved and we chose optimum crosslinking time 2 h according to the morphological observation and the mechanical properties analysis. FTIR proved that crosslinking did not change the chemical structure of collagen and PEO, thermal gravimetric analysis showed that the thermal stability of crosslinked collagen nanofiber membrane improved slightly, while water retention deteriorated. X-ray diffraction analysis showed that crosslinking changed the distance between peptide chains, result in a more compact structure between collagen molecules.non-toxic aqueous acetic acid as the spinning solvent, glutaraldehyde(GTA) as crosslinking agent, collagen nanofiber membrane is made of collagen and PEO through electrospinning. scanning electron microscopy, infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis show that: collagen nanofiber membrane with uniform diameter, good mechanical properties and water resistance,our preliminary work laid the foundation for the further application.of collagen nanofiber membrane.