Give spiders nanotubes to eat — get carbon-reinforced silk

Spider silk is one of the more extraordinary materials known to science. The protein fiber, spun by spiders to make webs, is stronger than almost anything that humans can make.

The dragline silk spiders use to make a web’s outer rim and spokes is amazing stuff. It matches high-grade alloy steel for tensile strength but is about a sixth as dense. It is also highly ductile, sometimes capable of stretching to five times its length.

This combination of strength and ductility makes spider silk extremely tough, matching the toughness of state-of-the-art carbon fibers such as Kevlar.

So it goes without saying that the ability to make spider silk even stronger and tougher would be a significant scientific coup. Which is why the work of Nicola Pugno at the University of Trento in Italy and a few pals is something of a jaw-dropper.

These guys have found a way to incorporate carbon nanotubes and graphene into spider silk and increase its strength and toughness beyond anything that has been possible before. The resulting material has properties such as fracture strength, Young’s modulus, and toughness modulus higher than anything ever measured.

The team’s approach is relatively straightforward. They started with 15 Pholcidae spiders, collected from the Italian countryside, which they kept in controlled conditions in their lab. They collected samples of dragline silk produced by these spiders as a reference.

The team then used a neat trick to introduce carbon nanotubes and graphene flakes into the spider silk. They simply sprayed the spiders with water containing the nanotubes or flakes and then measured the mechanical properties of the silk that the spiders produced…

In other words, giving spiders water that is infused with carbon nanotubes makes them weave silk stronger than any known fiber.

Woo-hoo. We have some fierce spider-critters here in New Mexico we should try this out on!

Gossamer silk from balloon spiders

Ballooning is a term used for the mechanical kiting that many spiders, especially small species…use to disperse through the air. Many small spiders use gossamer or especially fine silk to lift themselves off a surface or use the silk as an anchor in mid air. The very fine silk used for ballooning has been called “gossamer” since 1325 and was not originally known to be produced by spiders; by extension, the same word is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term “balloon silk” to the threads that mechanically lift and drag systems.

A spider or spiderling after hatching will climb as high as it can. The spider then stands on raised legs with its abdomen pointed upwards. This is known as “tiptoeing”. After that, it starts releasing several silk threads from its abdomen into the air, which automatically form a triangular shaped parachute. The spider can then let itself be carried away by updrafts of winds, where even the slightest of breeze will do. Most rides will end a few metres later, or a spider can be taken up into a jet stream, which depends on its mass, posture, the convection air current, drag of silk and parachute to float and travel high up into the upper atmosphere.

One of my favorite early summer signs. The prevailing westerlies always catch many gossamer threads along our eastern fenceline.

Scientists GM silkworms to produce artificial spider silk

A research and development effort…has succeeded in producing transgenic silkworms capable of spinning artificial spider silks.

“This research represents a significant breakthrough in the development of superior silk fibers for both medical and non-medical applications,” said Malcolm J. Fraser Jr…. “The generation of silk fibers having the properties of spider silks has been one of the important goals in materials science.”

Natural spider silks have a number of unusual physical properties, including significantly higher tensile strength and elasticity than naturally spun silkworm fibers. The artificial spider silks produced in these transgenic silkworms have similar properties of strength and flexibility to native spider silk.

Silk fibers have many current and possible future biomedical applications, such as use as fine suture materials, improved wound healing bandages, or natural scaffolds for tendon and ligament repair or replacement. Spider silk-like fibers may also have applications beyond biomedical uses, such as in bulletproof vests, strong and lightweight structural fabrics, a new generation athletic clothing and improved automobile airbags…

Fraser, with the assistance of University of Wyoming researcher Randy Lewis, a biochemist who is one of the world’s foremost authorities on spider silk, and Don Jarvis, a noted molecular geneticist who specializes in insect protein production, genetically engineered silkworms in which they incorporated specific DNAs taken from spiders…

Since silkworms are already a commercially viable silk production platform, these genetically engineered silkworms effectively solve the problem of large scale production of engineered protein fibers in an economically practical way.

Bravo! I doubt if we even have to worry about vegan Luddites fretting over people eating these silkworms.

Cripes. Materials engineers/structural designers will be having a ball.