The dream of swinging from buildings like a superhero is one shared by many. While the ability to support human weight with a web isn’t possible yet, some US scientists have developed artificial silk that can lift objects up to 80 times its own weight. This material is not only stronger than natural spider silk but also provides possible applications in various industries such as medicine and construction.
The initial breakthrough was actually an accident. Dr. Marco Lo Presti, a materials scientist, was working on a project to create strong adhesives when he noticed something strange. While cleaning his glassware with acetone, a solvent known for breaking down materials, he observed a web-like substance forming at the bottom of the glass.
The process behind how it occurred was actually quite simple. Dr Lo Presti used silk fibroin which was obtained from cocoons of the Bombyx mori silkworm after it was boiled in a special solution. Silk fibroin solutions can form a semi-solid hydrogel, a material that is mostly liquid but acts like a solid, once exposed to organic solvents like ethanol—or in this case, acetone. The only issue with this is that it takes several hours for the hydrogel to form, making it inefficient for the purposes that it was needed for.
Dr Lo Presti and his team managed to solve this issue using an unexpected chemical: dopamine, the same one that provides feelings of pleasure and satisfaction in the brain. However, it is also used in the making of adhesives. When dopamine is added into the mix, the solidification process is almost instant. The silk quickly creates high-tensile strength fibres that are also very sticky.
The next issue was that the fibres needed to be spun, so Dr Lo Presti’s team used a needle with two holes. The silk went through the middle, and acetone went on the outside, so the silk would be surrounded by acetone and solidify quickly. The acetone evaporated mid-air, and all that remained was a fibre that was connected to the object it was pointed to. The researchers then enhanced the fibre using chitosan, a derivative of insect exoskeletons which made the fibre have up to 200 times their original tensile strength, as well as having 18 times the adhesive capabilities.
The innovation of this artificial silk has many potential applications. This can range from medical sutures and bandages as an alternate way to seal wounds, or potentially for construction purposes as the material gets stronger. Whilst not allowing us to replicate the lives of our favourite superheroes, we will continue to find uses for artificial silk and be inspired to let fiction shape the inventions we make.