59. Electrospun Fibers from Proteins

Due to the distinct advantage of silk for various applications, considerable attempts have been made to reproduce silk in the laboratory with specific properties for targeted applications. For instance, to exploit the advantages of protein-based biomaterials and nanostructures for medical applications, silk fibroin was electrospun into fibers [10Zha]. To form the fibers, silk (Bombyx mori) was first degummed to remove sericin. Later, the silk fibers were dissolved in 9.3 M lithium bromide solution at 60 °C, and the dissolved solution was dialyzed against a 2,000 molecular weight membrane to obtain a 3–7.2 % protein solution [10Zha]. In addition, lyophilized silk fibroin was also dissolved using HFIP at room temperature. Silk solutions were blended with polyethylene oxide (PEO) to improve spinnability and enable fiber formation. Fibers with relatively larger diameters, between 700 and 880 nm, were obtained. Electrospun mats obtained were treated with methanol to induce crystallization in silk and transform the silk into β-sheet configuration. Methanol treatment removed PEO and increased the surface roughness of the fibers [02Jin]. In another study, silk fibroin has been electrospun and the potential of using the silk nanofibers for various applications has been studied [08Kaw, 05Kim]. Silk nanofibers with diameters from 8 to 2,500 nm have been produced and used for tissue engineering [09Zha].