The Ultimate Band-Aid

MIT engineers have developed a nanoscale biological coating that can halt bleeding almost instantaneously, an advance that could dramatically improve injured soldiers’ survival rates.

The researchers, led by chemical-­engineering professor Paula Hammond ‘84, PhD ‘93, coated sponges with a spray that includes thrombin, a clotting protein found in blood. The sponges can be stored stably and carried by soldiers or medics, and they could also prove valuable in civilian hospitals.

“The ability to easily package the blood-clotting agent in this sponge system is very appealing because you can pack them, store them, and then pull them out rapidly,” ­Hammond says. The sponges can also be molded to fit the shape of any wound.

Uncontrolled bleeding is the leading cause of preventable trauma death on the battlefield. Traditional methods to halt bleeding, such as tourniquets, are not suitable for the neck and many other parts of the body. More recent inventions such as fibrin dressings and glues have a short shelf life and can cause an adverse immune response, and zeolite powders made of very absorbent minerals are difficult to apply under windy conditions and can cause severe burns. Bandages made of chitosan, a derivative of the primary structural material of shellfish exoskeletons, have had some success but can be difficult to mold to complex wounds.

Hammond’s team came up with the idea of coating existing, highly absorbent gelatin sponges with alternating nanoscale layers of thrombin and tannic acid, a small molecule found naturally in tea. This approach allowed a large amount of thrombin to be packed into the sponges, coating even the interior pores, and helped protect the thrombin in a stable form. Once sprayed, some sponges were stored for more than a month before use.

“Now we have an alternative that could be used without applying a large amount of pressure and can conform to a variety of wounds, because the sponges are so malleable,” says Anita Shukla, PhD ‘11, lead author of an Advanced Materials paper describing the research.

The researchers, whose work is supported by MIT’s Institute for Soldier Nanotechnologies, have filed a patent application on this technology and on similar sponges coated with the antibiotic vancomycin. Hammond’s lab is now working on combining the blood-clotting and antibiotic properties in a single sponge.