Study On The Preparation And Properties Of Ultrafine, Large Pore Size Silk Fibroin Based Composite Nanofibers For Tissue Engineering

The fiber membrane, which is prepared by the electrospinning technology, can be used astissue engineering scaffold. As a carrier of cell adhesion and proliferation, tissue engineeringscaffolds should have suitable for cell growth of the pore structure, high porosity and goodmechanical properties. But the fiber scaffold, is prepared by electrospinning, its compactarrangement of fibers, small pore and small porosity limit the growth of the cells within thescaffolds. Based on the electrospinning technology, combined with material abandon method,ultrasonic processing method and micro–nanofibers deposite method, Silk fibroin base fiberscaffolds with different pore size were prepared.Poly(lactic acid)/Silk fibroin (PLA/SF) composite nanofibers were prepared byelectrospinning and were treated for2hours by water vapor. After the treatment, there was noobvious inter-fiber conglutinating and swelling phenomenon between fibers, conformation of SFmainly for β-sheet structure. Using material abandon method, by the jet electrospinningtechnology, Polyethylene oxide (PEO) as the abandoned material, the PEO-PLA/SF compositenanofibers were prepared. The PEO-PLA/SF composite nanofibers were treated for2hours andthen be immersed in the deionized water to remove the PEO fibers completely. Through changethe content of the PEO fibers, PLA/SF composite nanofibers with different pore size wereprepared. The results showed that with the increase of the content of PEO fibers, the pore sizeand the porosity of the PLA/SF composite nanofibers increased. And the rupture stress and strainof the fibers decreased, but its rupture stress was still bigger than the fibers which were nottreated. PLA/SF fiber scaffolds were non-toxic and mouse embryonic fibroblasts(NIH-3T3cells)adhered and proliferated well on them. The PLA/SF fiber scaffolds with large pore size andhigh porosity were more advantageous to the growth of cells.PLA/SF composite nanofibers were treated for20min by methanol. After the treatment,there was obvious swelling phenomenon between fibers, conformation of SF mainly for β-sheet structure. And the rupture stress of the PLA/SF composite nanofibers increased significantly, butthe rupture strain decreased obviously. After the methanol treatment, the PLA/SF compositenanofibers were immersed in20ml deionized water, ultrasonic processing within0℃waterbath in order to change their pore size. The results showed that under the same processing time,with the increase of ultrasonic power, fibers deposited looser, pore size increased; under the sameultrasonic power, with the increase of the ultrasonic processing time, fibers deposited looser,pore size increased. After the ultrasonic treatment, the thickness of the fiber membranesincreased, became the three dimensional structure. NIH-3T3cells on the PLA/SF fiber scaffoldshad good growth status; the PLA/SF fiber scaffold, which were treated by ultrasonic, with largepore size and high porosity were more advantageous to the growth of cells.By micro–nanofibers deposite method, the fiber membranes with different pore size wereprepared. By the jet electrospinning technology, Poly(caprolactone)(n)-Poly(caprolactone)/silkfibroin(n)(PCL(n)-PCL/SF(n)) composite nanofibers, and PCL(m)-PCL/SF(n)compositemacro-nanofibers under different rotational speed were prepared. The results showed that underthe same rotational speed, the pore size and porosity of PCL(m)-PCL/SF(n)compositemacro-nanofibers were larger than the PCL(n)-PCL/SF(n)composite nanofibers, PCL(m)-PCL/SF(n)composite macro-nanofibers had higher rupture stress, but its rupture strain was lower thanPCL(n)-PCL/SF(n)composite nanofibers;with the decrease of the rotational speed, themacro-nanofibers of the PCL(m)-PCL/SF(n)composite macro-nanofibers deposited looser, poresize increased, the rupture stress increased, but rupture strain decreased. PCL-PCL/SF fiberscaffolds were non-toxic, and NIH-3T3cells on the PCL-PCL/SF fiber scaffolds had goodgrowth status; cells on the PCL(m)-PCL/SF(n)fiber scaffolds with large pore size and highporosity has better growth status. The PCL(m)-PCL/SF(n)fiber scaffolds with large pore size andhigh porosity were more advantageous to the growth of cells, which had good prospect ofapplication in tissue engineering scaffolds.