Production of super-tough artificial “dragline” silk in cell culture

Highlights

• Spider silk is about three times as strong and twice as elastic as silkworm silk but spider behaviour precludes its production by spiders in captivity.
• Dragline silk, the strongest spider silk, is one of seven types produced by orb-weaving spiders, is 25 times as tough as high-tensile steel and three times tougher than Kevlar, the strongest synthetic fiber ever made.
• The genes that encode the two dragline silk proteins (ADF3 and ADF4) were introduced into an insect-infecting baculovirus. These genetically engineered (recombinant) viruses were then used to infect tissue cultures of insect cells derived from the fall armyworm caterpillar, which produce large amounts of recombinant proteins.
• ADF-4-based micro-fibers were found to spontaneously self-assemble inside the insect cells and form fibers

Our Innovation

 Derivatives of sections of the dragline silk gene ADF4 of the cross-bearing garden spider (Araneus diadematus) were utilized to construct   novel synthetic sequences . When  recombinant viruses expressing  the synthetic sequences were used to infect insect cells, never-before observed spontaneous self-assembly of dragline silk fibers occurred.

Key Features

• Novel synthetic sequence not used previously
• The spider silk is produced through in vitro tissue culture in fall armyworm insect cells infected by a recombinant baculovirus.
• Fibers self-assembled in the insect cells are currently too short to be used in conventional spinning processes.
• A simple purification protocol results in very clean recombinant dragline silk fibers

Development Milestones

• Production of longer synthetic spider silk fibers suitable for commercial applications
• Upscaling spider silk protein production to commercial scale

The Opportunity

• Tremendous market potential for high-strength, low-weight materials such as very tough, low weight bullet-proof vests, new type of reinforced fishing lines, parachute cord, and new types of textiles
• If cost-effective production only results in small quantities, it may be used as biodegradable surgical sutures for microsurgery and, by coating the microfibers with heavy metals, as microconductors for electronics applications.