The Spininig Method Of Regenerated Spider Silk And Their Structure And Properties

Spider silk is a flexible, lightweight fiber with extraordinary strength and toughness. Thus it could have important applications in impact-proof textiles or other structural fabrics where strong, flexible materials are desired. Moreover the inherent biocompatibility of silk could be exploited in the fields of controlled release biomaterials and scaffolds for tissue engineering. Recent success in the identification artificial synthesis and expression of genes coding for spider silk proteins have opened the possibility of biotechnology-based large-scale production of spider silk proteins. A challenging avenue of research remains in learning how to process the raw protein powder into marketable structural materials.The dragline silk and eggcase silk of Araneus Ventrcosus spiders are collected as our study object.The comparative structural characters of regenerated spider dragline silk solution obtained in different solvents and technologies were investigated. The results of SDS gel electrophoresis showed the silk dissolved in LiBr had wider molecular weight distribution than in HFIP. The secondary structures of the silk film cast from the LiBr solution were α -helix, β-sheet and random coil. But the film obtained from HFIP solution was dominated by α -helix and random coil. Raman spectra showed the conformation of spider silk film dried from LiBr regenerated spider silk solution didn't have obvious change with temperature. The regenerated dragline silk solution use HFIP as solvent has better spinnability compared with LiBr.Electrospinning was used to fabricate nanoscale fiber mats of Araneus Ventricosus dragline silk and eggcase silk (ERDSF and ERESF). Both dragline and eggcase silk fibers were dissolved in HFIP solvent as spinning solutions. The morphology , crystalline structure, molecular conformations and mechanical properties were investigated by scanning electron microscopy (SEM), , Wide angle X-ray diffraction (WAXD), FTIR spectroscopy, DSC and electronic tensile instrument, respectively. Effects of electric field and tip-to-collection plate distance on morphology and diameter were measured. Both twokinds of regenerated spider silk fibers were well-crystallized during the process of electrospinning. FTIR spectra reveal that the conformation of a -helix, 3 -sheet and random coil exist simultaneously in electrospun regenerated dragline and eggcase silk nanofibers. Both ERDSF and ERESF have similar thermal resistance compared with natural dragline silk and eggcase silk. ERDSF have relatively higher mechanical properties than ERESF. After a week latter, the breaking strength of both films were decreased while the breaking elongation were not changed so much.Both the ERDSF and the ERESF were treated with methanol. The WAXD reveals the degree of crystallinity of both films were highly increased.The secondary structure were investigated by FTIR, a -helix and random coil structure were transformed to 3 -sheet by a post treatment with methanol. Tg of ERDSF and ERESF were gone up after treated by methanol showed by DSC curves . The breaking strength of both treated films dramatically increased while the breaking elongation declined.