Scientists at Tufts University have made a remarkable advancement by creating a fluid that transforms into a robust, adhesive fiber capable of lifting objects many times its weight, drawing inspiration from the legendary superhero Spider-Man.
For years, researchers have sought to develop strong fibers that could be utilized as tethers, looking to the silk produced by various insects, including spiders and moths, for guidance. However, mimicking the stiffness, elasticity, and stickiness of spider silk has been a tough challenge—until now.
A study published in Advanced Functional Materials reveals that a silk protein from moths, known as fibroin, can be enhanced with specific additives and then extruded through a narrow needle, resulting in a strong, sticky fiber.
“I was working on a project to create ultra-strong adhesives using silk fibroin, and while cleaning my lab glassware with acetone, I noticed a web-like material forming at the bottom of the container,” explained Marco Lo Presti, one of the study’s co-authors.
The researchers initially aimed to duplicate spider silk but found that fibroin solutions transformed into a semi-solid gel when they were treated with chemicals like ethanol or acetone over several hours. However, introducing dopamine significantly accelerated the solidification process, allowing them to produce high-tensile, sticky fibers almost instantly.
The scientists noted that the dopamine facilitates the silk protein’s conversion from liquid to solid by removing water content. Remarkably, they discovered that a thin stream of the silk solution, when coated in acetone, would solidify into a sticky fiber as it was ejected from a specially designed needle. As the acetone evaporated, the fiber would stick to any surface it encountered.
Incorporating chitosan—an ingredient found in insect exoskeletons—boosted the fibers’ tensile strength by up to 200 times. Chemicals such as borate buffer also enhanced their adhesive properties by around 18 times.
The diameter of these new fibers can be customized, ranging from as thin as a human hair to about half a millimeter, depending on the size of the needle used. These fibers have shown the ability to lift loads exceeding 80 times their own weight.
Testing demonstrated that they could successfully grasp a variety of items, including a metal bolt, a laboratory tube floating on water, a scalpel partly buried in sand, and a block of wood from a distance of around 12 centimeters.
While spider silk is still about 1,000 times stronger, the researchers are optimistic that these new fibers can be further perfected for various applications. “This process allows for a finely tuned creation of adhesive hydrogel fibers that form almost instantly,” Dr. Lo Presti remarked. “It’s truly a material inspired by superheroes.”