Abstract
Spider major ampullate silk fibers have been shown to display a unique combination of relatively high fracture strength and toughness compared to other fibers and show potential for tissue engineering scaffolds. While it is not possible to mass produce native spider silks, the potential ability to produce fibers from recombinant spider silk fibers could allow for an increased innovation rate within tissue engineering and regenerative medicine. In this pilot study, we improved upon a prior fabrication route by both changing the expression host and additives to the fiber pulling precursor solution to improve the performance of fibers. The new expression host for producing spidroin protein mimics, protozoan parasite Leishmania tarentolae, has numerous advantages including a relatively low cost of culture, rapid growth rate and a tractable secretion pathway. Tensile testing of hand pulled fibers produced from these spidroin-like proteins demonstrated that additives could significantly modify the fiber’s mechanical and/or antimicrobial properties. Cross-linking the proteins with glutaraldehyde before fiber pulling resulted in a relative increase in tensile strength and decrease in ductility. The addition of ampicillin into the spinning solution resulted in the fibers being able to inhibit bacterial growth.
Highlights
Silk is a natural composite fiber containing protein at its core [1] and has been used in a wide array of applications from traditional textiles to medical devices
A 6-histidine (His6) tag was placed on the C-terminal end of the deduced protein sequence and a secretion signal from L. mexicana invertase was added to the N-terminal end of the deduced protein sequence
Two expression cassettes were assembled in pKSNEO, one each for MaSp1 and MaSp2, containing eight copies of the respective block repeat domain, as described in the Materials and Methods section (Fig 1)
Summary
Silk is a natural composite fiber containing protein at its core [1] and has been used in a wide array of applications from traditional textiles to medical devices. While most of the silk used within commercial applications has been traditionally collected from silkworms, other naturally produced silk fibers, such as those produced by spiders, have been shown to have relatively superior and unique mechanical properties. Spiders can produce up to seven different silk fiber types that are each specialized for specific applications within their natural environment [2]. This variety in mechanophysical properties makes spider silk fibers attractive for new biomaterials development [3]. Dragline silk, which makes up the reels within orb weaver webs, is the most characterized spider fiber and has been shown to display specific tensile characteristics that are higher than the properties of steels and other man-made materials [4,5]
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