An international team of researchers has demonstrated a way of spinning a new type of fiber that could improve on how spiders create their own silk, one of the strongest and most resilient materials known. The team decoded the complex structure of spider silk and how it is produced to develop a synthetic material that could lead to new biomedical materials for applications such as sutures and scaffolding for organ replacements.

A unique aspect of the study was managing to synthesize silk that offers properties specifically tuned for their intended uses. As reported in the journal Nature Communications [Lin et al Nat. Commun. (2015) DOI: 10.1038/ncomms7892], simulations and experiments were used to provide a means to design artificially spun fibers with particular characteristics of strength, elasticity and toughness that improved upon natural silk.

"When you spin it, you create very strong bonds in one direction"Markus Buehler

The proteins for the synthetic fibers were developed by genetically modifying bacteria to create those that spiders usually produce. The proteins were then extruded through microfluidic channels in a controlled way designed to copy the effect of a spinneret, the organ spiders use to produce their silk. This spinning process meant the molecules of the constituent proteins lined up to produce strong fibers and, as the molecules are a blend of hydrophobic and hydrophilic compounds, they can align to form fibers much stronger than their constituent parts. As researcher Markus Buehler said, “When you spin it, you create very strong bonds in one direction”. However, it is also vital to achieve the correct blend of proteins to produce the fibers, as a greater amount of hydrophobic proteins prevents any fibers being spun.

Using simulations allowed for a large range of proteins to be assessed to identify changes in stiffness so the team could focus on the most effective compounds. It also avoids spending a long time synthesizing a protein that turns out not to have the right properties, and having to start again. Controlling the properties directly permits the development of fibers even stronger than natural ones as characteristics can be chosen for specific needs – for example, designing fibers for use as surgical sutures would need greater strength and but to be less stretchy.

Another advantage is that the material’s processing can be carried out at room temperature with water-based solutions, making the scaling up of manufacturing straightforward. However, until now the fibers produced have not been as strong as natural spider silk, but with the basic process now established, the team hope to fine-tune the materials and improve upon their strength.