BioSteel – Proteins as Flexible Alternatives to Steel

Hari Krishnan R, SRM Institute of Science and Technology

Introduction                                                              

Recombinant DNA technology has been an important developmental tool for mankind since the last few decades, and the recent advances in genetic manipulation have benefited various fields including medicine, agriculture, and industries. Most of the synthetic products we use today are slowly being replaced with commercially viable and effective natural alternatives that are being made utilizing the latest technologies and science, and one such is the BioSteel. BioSteel is the trademark name of a tough biopolymer-based material made from a recombinant Dragline silk proteins extracted from the milk of a transgenic goat. This product was developed by a Canada-based company Nexia Biotechnologies along with the University of Wyoming and Utah State University.

Features of Spider Dragline Silk

Spider dragline silk is known to be highly flexible and is 7-10 times stronger than regular steel and can also withstand temperatures up to 600 ⁰F. The production and the composition of this material are highly eco-friendly compared to synthetic products and is a promising material for fishing lines. Being natural, this can be used as biomaterials for various purposes including medical sutures, implant coating. This material is highly elastic, making it useful for the development of artificial tendons and ligaments. Several studies also explain the tendency of this material to be used in bulletproof vests.

Production of Transgenic Goat Expressing Silk Protein

Spider dragline silk is an extraordinary material with high strength and toughness and impressive biophysical and mechanical properties. The major component of this silk is the Spidroin-1 and Spidroin-2 proteins. Scientists of Nexia Biotechnologies extracted the golden orb weaver genes namely, MaSp1 and MaSp2 (both coding for spidroin class proteins) from Nephila clavipes commonly known as the golden silk spider. These genes are incorporated into the DNA of goats in such a way that the silk protein is expressed in the Mammary gland. Females of these transgenic goats tended to secrete the silk- protein with their milk. 

Turning Milk to Fiber

The downstream process involves the milk being subjected to density gradient centrifugation which separates the silk protein (currently in a liquid form) from the fats and cream of the milk based on its weight. Then the protein is filtered out, then dissolved in a water-based solvent, and subjected to High-moisture extrusion. High moisture extrusion is a method for texturizing protein into a Fiber product and this is carried out at high temperatures. The end product of the process will be a liquid protein which once reacted with air, hardens and forms a solid-granules. These are then reacted with alcohol to further solidify and dehydrate to remove excess water. This dried silk protein is then subjected to electrospinning technique to form nanofibers and nano-meshes. These fibers have an elongation range of 20-45% and have tenacities in the range of 2-3 g/deniers.

Current and Future Prospects

Nexia Biotechnologies is the only company to produce spider silks from transgenic goat’s milk. A Utah State University professor, Randy Lewis, and his lab have produced spider silk proteins from Recombinant E. coli and milk of recombinant goats. Although Nexia Biotechnologies produced these goats, they went bankrupt in 2018 and had to sell the 2 goats to Canada Agricultural Museum. But currently, this research is carried out in Randy Lewis’s Lab. The US navy has funded $420,000 for this research as they have a plan to modify and use this material to stop vessels by entangling the propellor.

The future research applications of silk fibers include developing stronger ropes, seatbelts, parachutes, and nets. There is also a scope of incorporating silk fibers in the textile industry for clothes and footwear. Scientists have recently identified similar strong fibers in Hag Fishes. Hag Fishes are marine craniates that secrete thick mucus slime as their defense mechanisms. This slime is known to contain strong polymer similar to spider silk and researchers are working on this for its production. It is incredible how small organisms like spiders are capable of producing these toughest fibers naturally and the growth of recombinant DNA technology and synthetic biology has helped us in genetic manipulation and production of such fibers commercially. Today, the large-scale production of recombinant silk proteins from transgenic animals is expensive and challenging but it is certain that as technology advances more new research will come to light.

Also read : Anaerobic gut fungi make way for novel antibiotic production

References:

1. Lazaris, A., Arcidiacono, S., Huang, Y., Zhou, J. F., Duguay, F., Chretien, N., Welsh, E. A., Soares, J. W., & Karatzas, C. N. (2002). Spider silk fibers spun from soluble recombinant silk produced in mammalian cells. Science (New York, N.Y.), 295(5554), 472–476. https://doi.org/10.1126/science.1065780
2. Robert F. Service (2002), Mammalian Cells Spin a Spidery New Yarn.https://doi.org/10.1126/science.295.5554.419b

ABOUT THE AUTHOR :

Hari Krishnan is a research enthusiast in Cell biology and Cell signaling. He is currently a final year Biotechnology Engineering student. He is a prolific Scientific writer with vast knowledge in diverse backgrounds of biotechnology. He is constantly focused on improving his knowledge and laboratory skills through various internships. A Chennai native, Hari is a spicy food lover and passionate about music and sports.

Social Media Info: https://www.linkedin.com/in/hari-krishnan-r-6bbb841aa/

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