Scientists Develop Dye for Wound Dressings to Indicate Infection

Posted: November 10, 2010

The wound dressing is formulated with an indicator dye that turns purple when the skin underneath is infected. *Photo courtesy of Fraunhofer EMFT

Scientists at the Fraunhofer-Einrichtung für Modulare Festkörper (EMFT), known in English as the Research Institution for Modular State Technologies, in Munich have developed an indicator dye for bandages and dressings that changes color if an infection develops underneath.

According to the scientists, bandages and dressings can be difficult and painful to remove, and removing the dressing is often necessary to check for infection. The scientists, therefore, created an indicator dye that reacts to the skin's pH when formuated into dressing materials and plasters.

Healthy skin and healed wounds typically show a pH below 5, according to the scientists, whereas infected skin has a pH value between 6.5 and 8.5. “If this value increases, it is shifting from the acid to the alkaline range, which indicates complications in the healing of the wound," noted Sabine Trupp, PhD, scientist at the Fraunhofer-EMFT, in a press release.

When the pH of the skin under the dressing rises, the color strip containing the indicator dye in the bandage turns from yellow to purple. This allows the dressing wearer to check the bandage without disrupting the healing process.

The scientists reportedly a number of challenges when creating the color strip. “The dye has to remain chemically stable when bonded to the fibers of the dressing material or the plaster to ensure that it does not get into the wound. At the same time, the indicator must show a clear change in color and also react sensitively in the right pH range,” said Trupp.