Fabrication and Characterization of Electrospun Wool Keratin/Poly(vinyl alcohol) Blend Nanofibers

Wool keratin/poly(vinyl alcohol) (PVA) blend nanofibers were fabricated using the electrospinning method in formic acid solutions with different weight ratios of keratin to PVA. The resultant blend nanofibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and tensile test. SEM images showed that the diameter of the blend nanofibers was affected by the content of keratin in blend solution. FTIR and XRD analyses data demonstrated that there were good interactions between keratin and PVA in the blended nanofibers caused by possibly hydrogen bonds. The TGA study revealed that the thermal stability of the blend nanofibers was between those of keratin and PVA. Tensile test indicated that the addition of PVA was able to improve the mechanical properties of the electrospun nanofibers. 1. Introduction In recent years, electrospinning has drawn much attention because it is an easy, versatile, and low cost technique to fabricate nanofibers. In general, electrospinning apparatus is made up of a high voltage supply, a capillary tube with a pipette or needle of small diameter, and a metallic collector [1]. At present, a large number of organic and inorganic materials has been electrospun into nanofibers. As polymer nanofibers have high specific surface area and porosity, they are mainly used for filtration [2], environmental cleaning [3], tissue engineering [4], battery materials [5], and so forth. The study of electrospun biopolymers mainly focuses on silk fibroin [6], chitosan [7], and gelatin [8]. But keratin has received relatively poor attention. Keratin is an abundant nonfood protein which is the major component of wool, hair, feathers, horns, and nails [9]. Keratin wastes, as poor quality raw nails from sheep breeding, by-products from the textile industry and horns, and nails and feathers from butchery [10], not only cause the waste of keratin resources but also pollute the environment. So, it is of great significance to study the recycling of keratin for effective utilization. Wool contains up to 95% by weight of pure keratin [11]. Compared with other proteins (e.g., fibroin and gelatin), wool keratin contains a large amount of cystine, which accounts for 7–20% of the total amino acids [12]. Wool keratin has a molecular weight ranging from 45 to 60？kDa of the microfibrils from the cortical cells to 6–28？kDa of the protein from the matrix [13]. At present, wool keratin has been prepared into films [14], sponge scaffolds [15], and nanofibers [16] and