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Wound dressings with drug depots

In Germany alone, approximately four million patients a year have to undergo chronic wound treatment. A wound dressing developed by the Hohenstein Institute in Bönnigheim in cooperation with the Society for the Promotion of Medical, Biological and Environmental Technologies (Gesellschaft zur Förderung von Medizin-, Bio- und Umwelttechnologien e.V. or GMBU) in Dresden could pave the way for new treatment strategies. The new wound dressing integrates and continually releases effective pharmaceutical substances on the basis of nanosol technology.

Researchers at the Hohenstein Institute investigated the release of drugs from nanosol-modified wound dressings in vitro and in vivo (on volunteers). © Hohenstein Institutes

Previously, substances for accelerating wound healing had to be applied directly to the wound, in the form of ointment for example, and then covered with a wound dressing. In the nanosol-modified wound dressing, individual cellulose fibres are coated with an inorganic matrix of inert silicon oxide (SiO2). The pharmaceutical substances are embedded into this matrix. When the fibres come into contact with moisture, the drugs are continuously released into wound.

In order to achieve the release of pharmaceutically active ingredients, the scientists modified and optimised the side chains of the SiO2 matrix according to the solubility and stability properties of the substances used (doping). In general, the sol stability decreases in relation to the amount of pharmaceutical substances added. In view of the planned large-scale production of such wound dressings, the experts worked out drug concentrations that guaranteed the stability of the nanosol dressing for as long as 10 days.

Due to the large number of pharmaceutically active substances available for treating wounds and their chemical diversity, Dr. Dirk Höfer's team chose substances that were representative of certain wound drug groups. The researchers investigated to what extent each substance under investigation was suitable for inclusion in the matrix and thus for development into products that can be used in different phases of wound healing and for different wound types.

New treatment methods for chronic wounds in view

Amongst other things, the scientists from Hohenstein have developed anti-bacterial wound dressings. The antibiotics are stably incorporated into the cavities of the nanosol layers and are continuously released into the moist environment of the wound in therapeutically effective doses, thereby contributing effectively to preventing wound infections. The integration of chitosan into the nanosol layers was also successful but unfortunately did not have the desired antimicrobial effect.

In contrast, the nanosol fixation of the vitamin precursor dexpanthenol, which promotes skin regeneration, appears to be quite promising. The substance can easily be attached to viscose using a technique developed by researchers at the Hohenstein Institute. Using textile bioassays, the researchers showed both in vitro and in vivo that the substance was released under the physiological conditions present in wounds and considerably improved the regeneration of the skin.

The new wound dressings contain drug substances (green fluorescence) that are embedded into a titanium dioxide matrix using the nanosol method. © Hohenstein Institute

The research project also revealed promising effects in terms of wound healing. The modification of the SiO2 sol enabled Dr. Höfer’s team to embed proteins that accelerate wound healing. They also showed that these proteins could be specifically released. Examples of such proteins include the following enzymes: bromelain, which breaks down the wound coating, trypsin inhibitor, which is a central regulatory protein involved in wound healing, and the growth factor insulin, which accelerates wound healing.

The results of the research project show the huge development potential for the therapeutic treatment of wounds using textiles. The large-scale implementation of the techniques developed at the Hohenstein Institute will enable the production of more efficient and cheap therapy management systems. Through the use of clinically tested and approved active ingredients, for example enzymatic substances (streptodornase) or growth factors (PDGF), it will be possible in future to produce wound dressings with drug depots which accelerate wound healing, simplify the treatment procedure and reduce the time required for the care of patients. However, Dr. Höfer envisages that the textile-based drug therapy will have to be thoroughly optimised and investigated before it can be applied as a medicinal product.

Further information:
Hohenstein Institute
Dr. Dirk Höfer

Website address: https://www.gesundheitsindustrie-bw.de/en/article/press-release/wound-dressings-with-drug-depots