Scientists have successfully replicated the complex molecular structure of spider silk, spinning it using artificial glands, mimicking nature's process of producing one of the world's toughest fibers. Scientists believe this breakthrough is a big step towards eventually being able to produce this highly adaptable and sought-after material with a wide range of real-world uses.
Researchers at the RIKEN Center for Sustainable Resource Science and the RIKEN Cluster for Pioneering Research achieved this feat using a new method, constructing an artificial silk gland designed to reflect the physical and chemical changes occurring in the spider's body.
It's not easy, making artificial spider silk extremely challenging due to the difficulty in replicating these complex biological processes. Biopolymer fibers are composed of large proteins with highly repetitive sequences known as spider silk. Beta sheets are molecular substructures in spider silk fibers that must be arranged neatly to give the silk its impressive properties.
Beyond that, artificial glands will require precise microfluidic mechanisms that allow proteins to self-assemble into filamentous fibers that not only look like the real thing, but also behave like the real thing.
"In this study, we tried to use microfluidic technology to simulate the production process of natural spider silk, which involves the flow and manipulation of small amounts of fluid in narrow channels," said Keiji Numata, who led the research at RIKEN. "In fact, one could say that the spider's silk gland is a natural microfluidic device."
The artificial gland, which resembles an unassuming rectangular box with recessed channels running along its length, is the result of trial and error in creating the right environment for a complex process to function as it does in nature. One mistake was using force to push the protein through the microfluidic system; it required negative pressure to pull the spinal cord solution through the device.
Once this hurdle was overcome, however, the team was able to create continuous filament fibers with aligned beta sheets, giving the material nature-like properties.
"It's surprising how powerful the microfluidic system can be once different conditions are established and optimized," said senior scientist Ali Malay, co-author of the study. "The assembly of the fibers was spontaneous, extremely fast, and highly reproducible. Importantly, the fibers exhibited a distinct layered structure found in natural silk fibers."
"High reproducibility" is a key attribute; successful replication has scalability issues, and farming spiders is nearly impossible for logistical and biological reasons. Low-cost, efficient production of silk could revolutionize the environmentally damaging textile industry, and its biocompatibility makes it an ideal candidate for a variety of medical uses, including sutures, artificial ligaments and connective tissue surgeries.
"Ideally, we want to have a real-world impact," Numata said. "To do that, we need to scale up the fiber production method and make it a continuous process. We will also use multiple metrics to evaluate the quality of the artificial spider silk and make further improvements based on that."
The research was published in the journal Nature Communications.