Preparation And Performance Of Collagen Based Electrospun Fibers/Silk Composite Material For Vascular Graft

Currently, artificial vascular transplantation is considered as the most effectivemethod to treat vascular diseases. The main problems of small diameter vasculargrafts are the poor hemocompatibility and low long-term patency rate. The issue ofhow to improve the long-term patency rate of small diameter vascular grafts continuesto be an important problem to be solved. Collagen is a natural ECM component ofmany tissues with excellent biocompatibility and hypoimmunity. Electrospun collagennanofiber sacffolds can mimic the three-dimensional network structure of naturalECMs which is important for cell attachment, proliferation and differentiation.However, mechanical properties of electrospun collagen fibers can’t meet therequirments. Textile based vascular prostheses has excellent mechanical properties,but poor biocompatibility. The goal of this research is to create collagen basedelectrospun fibers/silk composite material to combine the desirable properties of eachcomponent and explore to produce mechanically strong, highly biocompatible,composite artificial vascular material.In this study, collagen and polyethylene oxide(PEO) were chosen as raw polymermaterials, with1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and50%(v/v)HFIP-aceticacid(AA) mixture as solvent, to prepare collagen/PEO blend electrospun fibers.Scanning electron microscopy(SEM) was used to observe fibers morphology. Theinfluence of solution parameters (solution concentration, collagen/PEO weight ratio,viscosity and electrical conductivity) and spinning technological parameters (voltage,distance and flow rate) on fiber morphology were investigated. The optimal spinningconditions were as follows:50%(v/v)HFIP-AA mixture as solvent, m(collagen):m(PEO)was70:30, total protein concentration at3%g/mL, spinning voltage range14kV,tip-to-target distance at15cm. flow rate at0.8mL/h.The physical and chemical properties of collagen/PEO micro-nanofibers produced under optimal spinning conditions were characterized by combinedtechniques of Fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD) andthermal analysis. The results indicated that the molecular interaction should existbetween collagen and PEO, and suggested no major chemical structural changesoccurred in these two polymers. Collagen/PEO fibers contained74%collagen whichwas approximate to initial dispersions contained70%collagen.In order to improve both water-resistant ability and mechanical properties ofcollagen/PEO micro-nanofibers, the fibrous membrane was crosslinked by25%glutaraldehyde(GTA) aqueous solution. When hydrated, our experimentsdemonstrated that electrospun collagen underwent a pronounced degree of coiling.And chose appropriate crosslinking time (12h) according to the morphologicalobservation and the mechanical properties analysis at dry and wet state. FTIR provedthat crosslinking did not change the chemical structure of composite webs, XRDshowed that the crystallinity of fibers decreased significantly after crosslinking, thethermal properties of crosslinked fibers decreased slightly which may result from thechange of crystalline structure or decrease in crystallinity of PEO.The preparation of collagen based electrospun fibers/silk composite artificialvascular material using two methods, including low temperature plasma treatment,biological glue or high concentration of collagen solution as adhesive. The compositematerial was analyzed using peel and extracorporeal circulation system simulationdevice to evaluate adhesion between the fibrous membrane and the fabric substrate.The results indicated that plasma technology has no obvious effects on silk surfaceadhesion properties. However, biological glue or high concentration of collagensolution as adhesive were utilized to improve the adhesion and durability of themicro-nanofiber coating signally. Composite interface remained intact after scouringby water for5days in extracorporeal circulation system simulation device.In this paper, Electrospun composite fibers of collagen (type-1) and polyethyleneoxide (PEO) polymers were prepared using a solution of1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and acetic acid (AA)(VHFIP:VAA=1:1),and studied the physical and chemical properties before and after crosslinking. On thisbasis, biological glue or high concentration of collagen solution as adhesive wereutilized to produce collagen based electrospun fibers/silk artificial composite material.The research could provide experiment basis and technical supports for furtherdevelopment of ideal artificial vessel materials.