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Volume 86 Issue 24 | p. 61 | What's That Stuff?
Issue Date: June 16, 2008

Liquid Bandages

Polymeric materials patch up acute and chronic wounds
Department: Science & Technology
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First Aid
Consumers can use over-the-counter liquid bandages (shown here) to cover small cuts.
Credit: Linda Wang/C&EN
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First Aid
Consumers can use over-the-counter liquid bandages (shown here) to cover small cuts.
Credit: Linda Wang/C&EN

Take a stroll through the first-aid aisle in a drugstore. Among the dizzying selection of gauze and medical tape and the myriad colors, shapes, and materials of adhesive bandages, you will likely find a few products labeled as "liquid bandages." Many first-aid kits are now also stocked with a small bottle of this wound-covering alternative. And don't be surprised if you go to the emergency room for stitches and the doctor pulls out glue instead.

Although traditional bandages, stitches, and staples are far from obsolete, many medical professionals, consumers, and even the military are turning to liquid bandages to patch up injuries ranging from hangnails to head wounds.

A liquid bandage is a colorless adherent material that can be sprayed or painted directly on a wound. It reduces pain by covering nerve endings and helps wounds heal by maintaining a proper moisture balance and keeping bacteria and debris out, says Ann Salamone, president of Rochal Industries, a private research company in Boca Raton, Fla., that develops polymer systems for wound care.

The bandages work by sealing the wound until the damaged area heals and the surrounding skin and bandage slough off. How long that takes depends on the type of liquid bandage and the depth of the wound.

Liquid bandages can stick better than plastic or fabric adhesive bandages to many hard-to-bandage areas, such as knuckles and between fingers. Wash the dishes. Go swimming. A liquid bandage won’t fall off.

Two general categories of liquid bandages exist. Skin protectants are over-the-counter (OTC) gels and sprays that can shield everything from superficial scrapes to large, chronic bedsores. The second category of liquid bandages is called suture replacements or tissue adhesives. Professional health care providers use this type of liquid bandage to join together more serious skin lacerations. Doctors and veterinarians may also use these materials to repair some cuts to internal organs or to close surgical incisions. Suture replacements are less traumatic for patients than staples or stitches because they do not require anesthesia or a return trip for removal.

A major difference between the two categories of liquid bandages is that suture replacements can be used on a bleeding wound, whereas skin protectants don’t successfully cover cuts that are actively oozing.

People had been using liquid bandages well before the medical versions came on the market. For centuries, humans have applied layers of honey, sorghum syrup, or tree sap to shield their wounds. Synthetic formulations of skin protectants approved for medical use today leave a polymer film on the skin when the solvent carrier evaporates. Water-based systems include poly(N-vinylpyrrolidone). Alcohol-based versions can contain nitrocellulose or poly(methylacrylate-isobutene-monoisopropylmaleate). And products with solvents such as hexamethyldisiloxane or isooctane contain acrylate or siloxane polymers.

Suture replacements are based on cyanoacrylates that polymerize when they come in contact with moisture from skin or tissue. This powerful class of instant adhesives is commonly known as “superglue.” In the 1960s, researchers considered using ethylcyanoacrylate superglue—the same found in hardware stores today—for closing up wounds, and soldiers even used it during the Vietnam War.

Despite positive results on the battlefield, ethylcyanoacrylate has never been approved for civilian medical use and should not be used on the skin for two main reasons: The short ethyl chains degrade in the body and release toxic compounds, and the manufacturing process is not sterile or monitored to prevent impurities. Long-chain octylcyanoacrylate-based glues were approved for medical use first in Canada and Europe and then in the U.S. by 1998.

Since then, some manufacturers have included octylcyanoacrylates in OTC liquid bandages. However, the industry is moving toward acrylate copolymers and solvents for OTC products, which make it more difficult for consumers to, for example, accidentally glue their foot to the floor, says Wayne K. Dunshee, a chemical engineer at adhesives company 3M.

Development of liquid first aid for complicated wounds in military situations continues. Earlier this year, the U.S. Food & Drug Administration approved the marketing of a hydrogel liquid bandage, intended for field soldiers, that can absorb up to one-third its weight in blood and fluids over 72 hours.

Soldiers can use the dressing to patch large, bleeding wounds until further medical care is available, says Sameer Shums, project director at Georgia-based company BioCure, which collaborated with Rutgers University researchers to develop the bandage.

The military applicator for the hydrogel dressing is a preloaded, double-barreled gun device that can be operated with one hand. The two liquid components combine during delivery, as a simple redox reaction cross-links the polyvinyl alcohol-based hydrogel in less than one second to form a colorless layer. Shums says the dressing can cool burns and that the research team is still working to incorporate additives that ease intense pain or make the material antibacterial.

Other researchers are also exploring various ways to make OTC liquid bandages antibacterial or match a range of skin tones, says Ibraheem T. Badejo, director of applied research for Closure Medical, a division of Ethicon located in North Carolina.

But with these advances in liquid bandages, will traditional adhesive bandages become scarce? Dunshee doubts that the liquid bandage will ever entirely supplant pads and tape because they have one component that liquid bandages don't: a reassuring cushion from the rest of the world.

 
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