SOMERVILLE, Mass. — Professor Fiorenzo Omenetto and research assistant Marco Lo Presti and their team at Silklab create silk-based inventions that are inspired by nature, such as silk from various insects and plants. The team has created underwater glues, edible coatings to extend the shelf life of food, and even light-absorbing material for solar panels. Their new invention is an adhesive that can be used on various materials, such as wood-based projects.
The silk adhesive was created from moth cocoons which are boiled in solution and broken down into proteins called fibroin. The silk fibroin solution can be extruded through needles to form a stream that solidifies into a fiber when exposed to air. The adhesive can hold up to 80 times its weight, as demonstrated by the researchers with various tests - a cocoon, a steel bolt, a laboratory tube floating on water, a scalpel partially buried in sand, and a wood block were held up from a distance of about twelve centimeters.
The breakthrough came about purely by accident. “I was working on a project making extremely strong adhesives using silk fibroin, and while I was cleaning my glassware with acetone, I noticed a web-like material forming on the bottom of the glass,” says Presti.
The researchers then enhanced the solution with chitosan, a derivative of insect exoskeletons that gave the fibers up to 200 times greater tensile strength, and borate buffer, which increased their adhesiveness 18-fold.
"Silk fibroin solutions can slowly form a semi-solid state when exposed to organic solvents like acetone, but the presence of dopamine, which is used in making the adhesives, allowed the solidification process to occur almost immediately," says Omenetto. "When the organic solvent wash was mixed in quickly, the silk solution rapidly created fibers with high tensile strength and stickiness."

"Our manufacturers are developing the project to be used in a commercial sense," says Omenetto. "This silk could be used in manufacturing industries like woodworking as the silk has already been proven to work as a glue."
With a little engineering from the Tufts manufacturers, the innovation could improve a variety of technological applications.
To read more about the invention, visit advanced.onlinelibrary.wiley.com.
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