Share:
Study New patch shows the healing process in wounds
Researchers in Switzerland are currently working on a patch that displays the status of wound healing without having to remove it. Especially the treatment of chronic wounds could be improved with the new development.
Control healing process
Even with minor everyday injuries, it is often extremely uncomfortable when the dressing is changed. It twitches and pinches, and sometimes a scabby wound starts to bleed again. Some simply wait until the plaster breaks loose on its own. This is not possible with chronic wounds. Here the healing process has to be checked regularly. A new type of wound dressing is intended to warn against poor wound healing - without having to remove the dressing.
Researchers are currently working on a patch that shows how a wound heals without it having to be removed. The development is particularly advantageous for the treatment of chronic wounds (Image: lirtlon / fotolia.com) When dressing changes, bacteria can colonize
Chronic wounds are when wounds do not heal after several weeks. For example, they may be a sequela of diabetes or circulatory disorders.
The treatment is much more complicated than with conventional wounds. As a rule, the wound dressing must be changed regularly, not only for reasons of hygiene, but also to examine the wound, to take smears and to clean it.
The skin is not only unnecessarily irritated in this way; it can also colonize bacteria - the risk of infection increases. It would be better if the bandage stayed on the skin longer and the nurses could read the condition of the wound from the outside.
Researchers are working on a new wound dressing
In recent years, there have been many advances in the treatment of such wounds. Just a few months ago, researchers from Leipzig and Dresden reported on a newly designed hydrogel, which also contributes to better wound healing.
And scientists at the Munich-based Fraunhofer Institute for Modular Solid State Technologies (EMFT) have already developed a patch that controls wound healing years ago.
Scientists from Switzerland are now also working on a novel wound dressing.
The experts of the Federal Materials Testing and Research Institute Empa are currently developing a high-tech system together with ETH Zurich, the Center Suisse d'Electronique et de Microtechnique (CSEM) and the University Hospital Zurich to provide nursing staff with relevant data on the condition of a wound it says in a message.
Luciano Boesel from the Empa department "Biomimetic Membranes and Textiles", who coordinates the project at Empa, explains: "A smart wound dressing with built-in sensors should one day provide information about the state of the wound healing process - so there is no need to change the dressing more frequently as necessary. "
This allows a gentler treatment for the patient and less effort for the nursing staff. In this case, less effort also means less costs: $ 17 billion was spent on wound treatment worldwide last year.
Wound healing in phases
When wounds heal, the body produces specific substances in a complex sequence of different biochemical processes that vary metabolic parameters. Depending on the phase increases or decreases about the amount of glucose and oxygen, and the pH value changes.
All these substances can be detected with special sensors. To do this, the experts are developing a fluorescence meter that can monitor several parameters simultaneously, which should be portable, inexpensive and easy to use.
It should allow to keep an eye on pH, glucose and oxygen levels during wound healing. If the values change, this allows conclusions to be drawn about further biochemical wound healing processes.
Especially useful for chronic wounds is the pH. For example, if the wound heals normally, it goes up to a value of 8, then drops to a value of 5 to 6. However, if a wound no longer closes and becomes chronic, the pH oscillates between 7 and 8.
So it would be helpful if the nursing staff at the wound dressing could be made aware with a signal that the value is constantly high. If the dressing does not have to be removed anyway for hygienic reasons, one could still wait at lower pH values.
And how do the sensors work? The idea behind it: If certain substances appear in the wound fluid, "tailor-made" fluorescent sensor molecules react with a physical signal.
They start to fluoresce, and some even change their color in the visible or in the ultraviolet range. Thanks to a color scale, you can interpret weaker and stronger color changes and deduce how large the amount of released substances is.
Luminescent molecules in UV light
Chemist Guido Panzarasa from the "Biomimetic Membranes and Textiles" department shows in the lab how a sample starts to fluoresce with sensor molecules. He carefully drops a pH 7.5 solution into a dish.
In UV light, the change is clearly visible. If he adds another solution, the luminosity fades again. A look at the vial of the solution confirms: The pH of the second fluid is lower.
The Empa team has designed a molecule composed of benzalkonium chloride and pyranine. While benzalkonium chloride is a substance that is also used for ordinary medicinal soap and works against bacteria, fungi and other microorganisms, pyranin is a dye found in highlighters and fluorescent under UV light.
"This biomarker works very well," says Panzarasa, "best at pHs between 5.5 and 7.5. The colors can be visualized with simple UV lamps, such as those available in the electrical shop. "
The Empa team recently published their findings in the journal "Sensors and Actuators B - Chemical".
The "designer molecule" has another advantage: Thanks to the benzalkonium chloride, it has an antimicrobial effect on the skin. Unwanted bacteria could thus be combated in the future by choosing the right dressing material.
Further evaluations, such as compatibility with cells and tissues, are still missing. Therefore, the researchers do not know how their sensor works in a complex wound.
Monitor wound via smartphone
To illustrate how a smart dressing could look practical in the future, Boesel puts a prototype on the bench.
"On wound dressings, the entire surface does not have to be equipped with sensors. It is sufficient if some small cylinders are impregnated with the pyranine-benzalkonium molecule and inserted into the carrier material. This will not make the industrial wound dressings much more expensive than they are now. They will be no more than a sixth to a fifth more expensive, "explains Boesel.
When Panzarasa drips various liquids with different pH values on all the small cylinders of the wound pad prototype, you can clearly see the lighter and darker points as soon as it switches on the UV lamp.
They are even visible to the naked eye. It glows bright yellow when high-pH liquids come in contact with the sensor. The scientists are certain: Since the pH value can be read out in such a simple manner and provides precise information about the acidic or basic state of the sample, such a wound dressing is well suited as a diagnostic tool.
With the fluorescence meter more accurate quantitative measurements of the pH value for medical purposes can be achieved.
In the future, the signals could also be read using a smartphone camera, Boesel said. Combined with a simple app, caregivers and doctors would have a tool that would allow them to easily read the wound status "from the outside" even without a UV lamp.
Even at home, patients would then have the opportunity to recognize an imminent chronic wound at an early stage. (Ad)