The management of chronic wounds is a long-term burden on the healthcare system. Take diabetic foot syndrome as an example: poor blood circulation in the feet means even a small pressure point inside the shoe can cause a wound, which often fails to heal properly within four weeks. Patients require frequent monitoring and dressing changes, and treatment can last up to a year, placing a strain on healthcare staff and increasing medical expenses.

Researchers at the Swiss Federal Institute for Materials Science and Technology (Empa) are exploring a new approach: using visible light to control the release of wound disinfectants. The research, led by Luciano Boesel and Giorgia Giovannini at the St. Gallen Laboratory of Bionic Membranes and Textiles, is currently in the laboratory stage.

The research team loaded the commonly used disinfectant chlorhexidine onto silica nanoparticles, and then encapsulated these particles with a polymer shell containing photo-switching molecules. When the material is irradiated by a visible LED, the structure of the photo-switching molecules changes, the polymer coating expands, its water permeability increases, and chlorhexidine is released from the silica core. After the light exposure stops, the polymer molecules contract, returning to their original impermeable state, and the drug release ceases. By adjusting the duration, intensity, or wavelength of the light exposure, the timing and dosage of the active ingredient's release can be controlled.

Boesel points out that compared to ordinary wound patches, this system is characterized by its ability to deliver medication more precisely, thereby reducing the risk of bacteria developing drug resistance. The research team also envisions combining this delivery system with wound sensors. Empa has previously developed sensors that can detect the quantity and type of bacteria in wounds. Integrating the two, silica nanoparticles can be loaded with different therapeutic agents, and the polymer coating can be equipped with light switches that respond to different wavelengths, selecting the appropriate wavelength of light for irradiation based on the detected infection type, thus achieving more targeted treatment. Boesel believes this will help change the current situation where standard wound care uses a similar approach regardless of the type of bacteria.

However, this technology is still a long way from clinical application. Currently, the system has only been tested in test tubes. The research team is in contact with several hospitals and plans to recruit doctoral students to advance further research and development. Even if progress is smooth, it will still need to go through multiple phases of clinical trials before obtaining medical device approval. For diabetic foot patients, this light-controlled release drug patch may still be several years away from practical use. But if it is ultimately successful, patients are expected to reduce the number of trips to the hospital, and the medical system may also benefit from reduced manpower requirements, even though the manufacturing cost of the patch itself is higher than that of traditional dressings.