Spider Webs May Soon Make Us All Strong Like Spiderman

There is no shortage of scientific inspiration to be found in the workings of nature. With hundreds of millions of years of evolution on her side, Mother Nature has achieved some remarkable feats that human scientists are only just beginning to approach. One area in which this is particularly relevant is that of biomaterials. Currently, a new crop of materials scientists is investigating the structure and composition of spiders’ silk – the toughest of all biomaterials – with an eye towards everything from artificial tendons and ligaments to drug-delivering bandages.

Seriously tough silk: the silk of the Madagascar Bark Spider is the toughest known biomaterial, far exceeding the performance of steel. Image by Ingi Agnarsson, Matjaž Kuntner, Todd A. Blackledge, doi:10.1371/journal.pone.0011234.Seriously tough silk: the silk of the Madagascar Bark Spider is the toughest known biomaterial, far exceeding the performance of steel. Image by Ingi Agnarsson, Matjaž Kuntner, Todd A. Blackledge, doi:10.1371/journal.pone.0011234.

Spider silk is made up of proteins and many spiders can produce of variety of these proteins for varying applications: stiff strands for bridging wide gaps, for example, or thin sticky strands for trapping prey. The properties of these fibers, which spiders have evolved over millions of years to produce, are remarkable and no synthetic human fiber can match them. They are tougher than steel while retaining a remarkable flexibility. They are moldable like a plastic, but with the optical properties of an inorganic material like silicon. They are biodegradable, biocompatible and environmentally friendly.

Unfortunately, making use of natural spider silk is an extremely time consuming and low-yield process. A spider must be caught in the wild and anesthetized. An electric motor is then attached to the end of one of its fibers and used to extract a silk thread, up to 100 m in length, directly from the spider's gland. Clearly, the development of a synthetic route to spider silk proteins would be considerably more effective. To accomplish this, researchers have determined the genes responsible for silk protein production and have spliced them into more practical organisms like E. coli or plants. Unfortunately, larger proteins – which yield stronger fibers – are more difficult to obtain from these genetically modified organisms. As such, the best synthetic silks are still only two thirds as strong as natural fibers.

Another biosilk: the cocoons of silk worms are also an important source and inspiration for biomaterials. Image by Krish Dulal.Another biosilk: the cocoons of silk worms are also an important source and inspiration for biomaterials. Image by Krish Dulal.

Nevertheless, the practical applications which will result from this type of research are manifold, making it well worth pursuing. Any product that requires extreme lightness coupled with extraordinary strength could benefit; for example, fighter pilot helmets or climbing ropes. However, biomedical applications are the prime targets. Spider silks, and equivalently those derived from silk worms and honey bees, have been proposed as materials for artificial tendons or ligaments, as drug delivery agents which dissolve at a pre-established rate in the body, as degradable heart monitors and other electronic devices, artificial corneas, biodegradable orthopedic hardware, or scaffolds for growing tissues or neurons. Additionally, protein-based biomaterials have the added benefit of being able to sense and respond to the surrounding environments making possible things like next-generation bandages that release antibiotics when faced with an infection.

The future of spider-based biomedical devices is such that a real life Spiderman, with ultra-strong tendons and advanced silk corneas, is a real possibility. No radioactive spider bite required.