Scientists Spin Silk From Artificial Spider Gland
A new microfluidic device can produce high-quality artificial spider silk.
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Researchers at the RIKEN Center for Sustainable Resource Science in Japan have successfully created a microfluidic device that can spin artificial spider silk.
The device uses negative pressure to pull a precursor solution along it, where it is subject to very precise chemical and physical changes that mimic the processes that occur naturally in a spider’s silk gland. The result is an artificial silk that is very close in structure to the real thing – but with none of the difficulties that come with spider farming.
The research is published in Nature Communications.
The search for artificial silk
With a tensile strength roughly equivalent to steel of the same diameter, spider silk is a remarkable fiber. It has a strength-to-weight ratio that is effectively unparalleled, all while being flexible, biocompatible and biodegradable. These properties have made spider silk a focus of great interest in the biomedical space, where these silks could be used for sutures or artificial ligaments.
So, why aren’t these things already made of spider silk? Unlike silkworm farming, spider farming comes with some extra difficulties. For example, when kept in close proximity, spiders tend to become very territorial and can even turn cannibalistic.
Natural spider silk farming is unlikely to be able to keep up with the demand for high-performance silk fibers. To get around this, scientists have tried to develop artificial silks based on spider silk. This is no small task – spider silk derives its exceptional properties from its very complex structure.
Natural spider silk is essentially a biopolymer fiber, made up of large proteins with highly repetitive sequences called spidroins. Molecular substructures called beta sheets are also present in the fiber, which must be aligned very precisely to give the silk its unique mechanical properties.
Recreating this fiber architecture artificially is a challenge that has puzzled scientists for decades.
“In this study, we attempted to mimic natural spider silk production using microfluidics, which involves the flow and manipulation of small amounts of fluids through narrow channels,” said Keiji Numata, team leader of the biomacromolecules research team at the RIKEN Center for Sustainable Resource Science. “Indeed, one could say that that the spider’s silk gland functions as a sort of natural microfluidic device.”
Using microfluidics to “spin” silk
Rather than trying to create artificial silk from scratch, Numata and his team decided to take a new approach and design a device that could mimic the biological processes that naturally occur inside a spider’s silk gland.
The result was a small, rectangular device with tiny channels grooved into it. To create artificial silk, a precursor spidroin solution is fed into one end of the device, which gets pulled through the microfluidic channels when negative pressure is applied. As the spidroins flow through the channels, they are exposed to different zones – such as a liquid–liquid phase separation zone and an acidification gradient – that begin to manipulate the spidroins. As the spidroins continue to move through the device, they reach the correct conditions for the proteins to begin self-assembling into silk fibers with the same complex structure as natural spider silk.
“It was surprising how robust the microfluidic system was, once the different conditions were established and optimized,” said senior scientist Ali Malay, one of the paper’s co-authors. “Fiber assembly was spontaneous, extremely rapid and highly reproducible. Importantly, the fibers exhibited the distinct hierarchical structure that is found in natural silk fiber.”
While their current device is very small, the researchers say that they are eager to start experimenting with scaled-up versions of the process that could produce commercially significant amounts of artificial silk. Such a development could help to mitigate some of the negative impacts of silk textile manufacturing, they say, while also making artificial spider silk a realistic material for biomedical applications.
“Ideally, we want to have a real-world impact,” said Numata. “For this to occur, we will need to scale-up our fiber-production methodology and make it a continuous process. We will also evaluate the quality of our artificial spider silk using several metrics and make further improvements from there.”
Reference: Chen J, Tsuchida A, Malay AD, et al. Replicating shear-mediated self-assembly of spider silk through microfluidics. Nat Commun. 2024;15(1):527. doi: 10.1038/s41467-024-44733-1
This article is a rework of a press release issued by RIKEN. Material has been edited for length and content.