Wound infection is certainly not a good thing, but overuse of antibiotics may lead to the proliferation of antibiotic-resistant bacteria, which is also not a good thing. That's where a new cotton bandage comes in, as it kills microorganisms without the use of antibiotics. The bandage, developed by Cornell University's Mohsen Alishahi and colleagues, contains an organic compound called lawsone (also known as hennotannicacid).

Associate Professor Tamer Uyar (left) and PhD student Mohsen Alishahi inspect cotton-based materials

This substance occurs naturally in henna leaves and is known for its antioxidant, anti-inflammatory and antibacterial properties. However, due to its hydrophobic (water-repellent) properties, it does not mix easily with and suspend in liquid solutions. This limits its bioavailability and prevents it from being well absorbed by the body.

Cyclodextrin is a carbohydrate with a hollow inner cavity and a hydrophilic (water-absorbent) outer surface. By being "hidden" within cyclodextrin molecules, lawsome molecules are able to be thoroughly mixed into liquid solutions.

This lawsome/cyclodextrin solution was then combined with non-toxic hydroxypropylcellulose. Next, the researchers used electrospinning technology to evenly coat an ordinary cotton pad with a layer of the mixture. The hydroxypropylcellulose in the coating now becomes nanoscale cellulose fibers, increasing the surface-to-volume ratio of the solution.

When tested in the laboratory alongside pure lawsone, coated cotton was found to be more effective as an antibiotic against Gram-negative and Gram-positive bacteria. It works better against E. coli and Staphylococcus aureus, effectively eradicating both bacteria.

Alishahi said: "Wound dressings should provide a suitable environment to promote wound healing and prevent infection. This dressing uses pure natural materials such as cotton, cyclodextrin and Lawsone, which has comprehensive antioxidant and antibacterial activities and can promote wound healing and prevent infection."

A paper on the research, funded by Cotton Inc., was recently published in the International Journal of Pharmaceutical Sciences.