|Frank Ko1,2, Milind Gandhi2, and Costas Karatzas3
1Fibrous Materials Laboratory, Department of Materials Science and Engineering, Drexel University, 31st and Market street, Philadelphia, PA 19104, U.S.A.
With an unparallel combination of strength and toughness amongst fibrous materials, spider silk has long been recognized as a model for the development of the next generation of super fibers. Dragline silk from major ampullate glands of spider, Nephila clavipes is a fibrous protein with unique characteristics of combined strength and elasticity . Silk is considered as an advanced biomaterial which can be utilized for various biomedical applications including drug delivery and tissue engineering scaffolds. The silk fiber has crystalline regions of anti-parallel β-sheet interspersed with elastic amorphous segments. These two segments are represented by two different proteins, MaSp1 (Major Ampullate Spidroin 1) and MaSp2 (Major Ampullate Spidroin 2) coded by different genes. The individual components, MaSp1 (Major Ampullate Spidroin 1) and MaSp2 (Major Ampullate Spidroin 2) of transgenic spider silk (BiosteelR) in different ratios were successfully electrospun to obtain nanofibers with diameter as small as 20 nm. In this study the feasibility of incorporating Carbon nanotubes (CNT) in the MaSp1 component of spider silk was investigated in order to tailor the molecular structure and thus the mechanical properties of silk fibers. To facilitate translation of the superior properties of the CNT to the silk fibril composite, aligned Masp1/CNT composite nanofibers were produced. The successful incorporation of CNT in the electrospun nanofibrils was confirmed by Raman spectroscopy. It was founded that the incorporation of 1% CNT in MaSp1 resulted in almost ten fold increase in the modulus of the aligned fibers and four fold increase in ultimate tensile strength.