The wound dressing changes color if there is an infection

Nanocellulose wound dressings that can reveal early signs of infection without interfering with the healing process have been developed by researchers at the University of Linköping, Sweden.

The study, published in Materials Today Bio, is another step toward treating a new type of wound.

Skin is the largest organ of the human body. Wounds interfere with the normal functioning of the skin and take a long time to heal, are very painful for the patient and, in the worst case scenario, can lead to death if not treated properly. In addition, non-healing wounds pose a huge burden to society, representing around half of all outpatient care costs.

In traditional wound care, the dressing is changed regularly, approximately every two days. To check if the wound is infected, the treatment staff should remove the bandage and perform an assessment based on appearance and tests. It is a painful procedure that interferes with wound healing as the scab bursts repeatedly. The risk of infection also increases any time the wound is open.

Researchers at the University of Linköping, in collaboration with colleagues from two other Swedish universities, Örebro and Luleå, have developed a wound dressing made of nanocellulose that can reveal early signs of infection without interfering with the healing process.

“Being able to see firsthand whether a wound has become infected, without having to remove the dressing, opens up a new type of wound care that can result in more efficient treatment and improve the lives of patients with difficult-to-heal wounds. It can also reduce the unnecessary use of antibiotics,” said Daniel Aili, professor in the Division of Biophysics and Bioengineering at Linköping University.

The pads are made of tightly mesh nanocellulose, preventing bacteria and other microbes from entering. At the same time, the material allows gases and fluids to pass through, something that is important for wound healing. The idea is that once applied, the dressing will remain in place throughout the entire healing process. If the wound becomes infected, the dressing changes color.

An uninfected wound has a pH value of around 5.5. When an infection occurs, the wound becomes more alkaline and may have a pH value of 8, or even higher. This is because the bacteria in the wound change their environment to match their optimal growth environment. A high pH value in a wound can be detected long before the presence of pus, pain or redness, which are the most common signs of infection.

In order for wound dressings to exhibit high pH values, researchers used bromtimol blue, BTB, a dye that changes color from yellow to blue when the pH value exceeds 7. For BTB to be used in dressings without compromise, it is loaded onto a silica material with pores only the size of a few nanometers. The silica material can then be combined with the dressing material without compromising the nanocellulose. The result is a wound dressing that turns blue when an infection occurs.

Wound infections are often treated with antibiotics that spread throughout the body. But if infection is detected at an early stage, local wound care may be sufficient. This is why Aili and his colleagues at Örebro University have also developed an antimicrobial agent based on lipopeptides that kills all types of bacteria.

“The use of antibiotics makes infection even more problematic, as multi-resistant bacteria become more common. If we can combine antimicrobial substances with pads, we minimize the risk of infection and reduce the overuse of antibiotics,” said Aili.

He added that the new wound dressings and antimicrobial agents were part of the development of a new type of outpatient wound care. But because all products to be used in medical care settings must pass rigorous and expensive testing, he said it could be five to 10 years before they become available.

Both studies are part of the HEALiX research project funded by the Swedish Strategic Research Foundation with the aim of developing new types of wound treatments. Funding has also received from, inter alia, the Swedish Government’s Strategic Research Area in Materials Science in Functional Materials (AFM) at Linköping University, Vinnova, the Knut and Alice Wallenberg Foundation and the Swedish Research Council.

Another job on the wound

Because of the cost to the healthcare system, wound care has attracted the attention of many biotech and biopharma companies.

In the past year alone, Swedish company Ilya Pharma completed global patent coverage for the use of modified lactic acid bacteria to treat wounds.

Another Swedish company, Omnio AB, a spin-off from Umeå University, demonstrated plasminogen is a regulator of inflammatory inflammation that could be used to treat chronic wounds with dysfunctional inflammation. The company says the drug could mean a global treatment revolution for wounds that never heal.

And earlier this year, British company SolasCure saw its maggot enzyme wound treatment close to reality.