The Preparation Of Regenerated Wool Keratinpolycaprolactone Nanofibers And Its Research In Biological Properties

The wool resources are seriously wasted in China, such as a lot of wool byproducts in woolen mill, wool raw materials not suitable for spinning. According to statistics, due to poor quality, processing loss, wasting and other reasons, more than 10 tons of wool resources have been abandoned in China every year. If we can recycle the waste of wool, not only can we reduce environmental pollution, but also can ease the current shortage of wool and other resources problem. Thus, in recent years, the research about extracting and reusing wool keratin is very active, and has made some achievements. But reports on the green, environmentally friendly and efficient method of extracting keratin are rarely. In this paper, a new kind extraction method of wool keratin powder was invented, and the wool keratin was electrospun with polycaprolactone(PCL) to study its structural properties, which provided a new material in the field of biodegradable and potential biomedical applications.Firstly, a new method for extracting wool keratin powder was invented, and the best extraction process of wool keratin was optimized to be as follows: the reaction pH value was 10, the reaction temperature was 65℃, reaction time was 5h and L-cysteine was added in an amount 2 wt.%. Under the optimum condition, the dissolving rate of wool was 70%, and the extraction rate of wool keratin powder was 56%(Mw >8kDa). The natural wool and regenerated wool keratin were analyzed by SDS-PAGE gel electrophoresis, biological microscope, XRD, FTIR-ATR, Raman, 13 C NMR, TGA and GPC, which showed that the molecular weight of regenerated wool keratin powder were mainly in 10 kDa, 40 kDa and 60 kDa. Dissolution process of wool was gradually dissolved after swelling. During the regeneration process of wool, keratin structure did not change greatly, but compared with the original wool fibers, the secondary structure of keratin changed from α-helix structure to β-pleated structure, and the hydrogen bonds between the macromolecular chains was broken. Part of disulfide bond was destroyed and there was no recovery in the drying process. The thermal stability of regenerated keratin was decreased.Secondly, the regenerated wool keratin powder and polycaprolactone(PCL) were dissolved in formic acid for electrospinning, and the spinning solution and electrospun membranes were studied by means of electrical conductivity, SEM, TEM, FTIR-ATR, XRD, TGA, breaking strength and contact angle analysis, which showed that the conductivity of the spinning solution increased with the adding of keratin powder. The concentration of spinning solution had a greater impact on the apparent morphological structure of electrospinning fibers. The beads were easy to form when the concentration was less than 8wt%, the smoothest and most uniform fibers were made when the concentration was 10wt%. The diameter of spun fibers decreased with the increasing of regenerated wool keratin content until failing to get the fibers in a certain value. Regenerated keratin and PCL had good compatibility in formic acid solvent, and the electrospinning fiber had obvious skin-core structure. In the electrospinning process, the hydrogen bonds were formed between the regenerated wool keratin and PCL. With the increasing of keratin content in the fiber, the crystallinity of the fiber was gradually decreased and the initial decomposition temperature was gradually lowered. With the addition of keratin, the degradation rate of the composite became slow, and the weight loss of the composite material reduced. The Young’s modulus of the composites reduced with the addition of keratin. The experimental results of mechanical properties were equivalent to other PCL/natural polymer matrix composite nanofiber membranes. Keratin/PCL electrospun membrane had good hydrophilicity. Keratin composite spinning with the PCL could assign new physical and chemical properties of wool.Finally, the biodegradability and biocompatibility properties of the regenerated wool keratin/PCL electrospun membrane were tested through ELISA, LSCM and SEM to analysis the growth state of the cells. Results showed that the simulated in vitro degradation experiments, the spinning membrane treated with PBS buffer solution was almost unchanged after 7week, where spinning membrane with high levels of regenerated keratin was slight swelling. Wool keratin/PCL electrospun membrane showed good compatibility to cells, adding keratin could promote cell growth. Regenerated wool keratin/PCL electrospun membrane is a very promising biological material.