Researchers at the Massachusetts Institute of Technology have produced samples of strong, resilient spider silk. The spun samples could lead to a variety of biomedical materials, including sutures and scaffolding for organ replacements.

The synthesized silk features properties specifically tuned for their intended uses. The fibers can be designed with specific characteristics of strength, elasticity, and toughness. Medical sutures, for example, require high strength and low stretch.

To make the kinds of normal proteins produced by spiders, the MIT team genetically modified the new synthetic fibers’ proteins. The proteins were then extruded through microfluidic channels designed to mimic the effect of an organ, or spinneret, that spiders use to produce natural silk fibers.

The researchers’ “spinning” process, in which the constituent proteins dissolved in water are extruded through a tiny opening at a controlled rate, causes the molecules to line up in a way that produces strong fibers. The molecules themselves are a mixture of hydrophobic and hydrophilic compounds, blended so as to naturally align to form fibers much stronger than their constituent parts.

The MIT project represents the first use of simulations to understand silk production at the molecular level. Using simulation allowed the engineers to scan through a large range of proteins, find changes in the fiber stiffness, and then home in on those compounds.