Black Widow Spider Silk Is So Strong a Lab Version Could Be Used to Build Bridges

Black widow spider silk is extremely strong. By weight, it is stronger than steel. This has made it of keen interest to scientists looking to recreate its incredible properties in the laboratory. Now, a team from the U.S. has edged a little closer.

"Practical applications for a material like this are essentially limitless," Gregory Holland, from the Department of Chemistry and Biochemistry at San Diego State University, told Newsweek.

Holland and colleagues have now published research in the journal PNAS to understand the process of how black widows turn proteins into these superstrong fibers. "We have known for decades that spider silk in general is incredibly strong. Stronger than high tensile steel by weight," Holland said. "Although most spider silks are strong, some are stronger than others, and the black widow silk that this study is focused on is one of the strongest."

Attempts to recreate the silk in a laboratory failed—something was happening at the nanoscale during the silk-making process that scientists did not understand.

black widow
A black widow creates silk in a laboratory. Scientists’ attempts to recreate silk in a laboratory failed. SDSU

The team sought to fill this knowledge gap by studying the silk protein solution on a minute scale. They found the proteins were comprised of hundreds of individual silk proteins. "These larger nanoscale assemblies were hypothesized to exist for nearly 15 years…for the first time we actually know what they look like," Holland said.

In a statement, study author Nathan Gianneschi said: "What we didn't understand completely is what goes on at the nanoscale in the silk glands or the spinning duct—the storage, transformation and transportation process involved in proteins becoming fibers."

Holland said now that we know what black widow spider silk is made of at a nanoscale, scientists can start creating better artificial versions.

"There are already smaller startup companies that are making synthetic spider silk," Holland said. "However, the silk does not have the superior mechanical properties of native spider silk. The reason for the subpar mechanical properties stems from an inability to replicate the natural spinning process in the laboratory.

"The type of detailed information we provide in the article regarding the native dope [the seeds from which natural silk fibers are spun] could be tested in synthetic spider silk spinning solutions and the conditions can be varied to get these structures. We think that these preassemblies of protein nanoparticles are critical for spider silk spinning. Another piece to a very complex puzzle."

black widow silk
Silk fibers originate inside a black widow’s protein gland, like this one. Scientists have struggled to replicate the spider’s spinning process. SDSU

Holland said that with the latest research, he sees "some big things coming in the next five to 10 years." The next challenges to overcome involve being able to produce large amounts of the protein in a cost effective way and being able to scale this up to an industrial level. They must also find a way to correctly replicate the spinning process.

"The processes to make fibers from synthetic silk proteins in the lab are extremely simplistic in comparison to what goes on in the spider's abdomen. We must understand what happens biochemically from the atomic to the macroscale." Once this is perfected, the applications are "essentially limitless," Holland said.

"High performance textiles for military and first responders, athletic gear, building materials for cable bridges and biomedical applications to name a few. The latter is transparent. Silk worm silk has already been shown to be an excellent biomaterial and is used in a number of 'real world' biomedical applications," Holland said.

Gianneschi said, "One cannot overstate the potential impact on materials and engineering if we can synthetically replicate this natural process to produce artificial fibers at scale."