New sunlight-powered nanospray heals infected diabetic wounds

Chronic infected wounds can take over daily life, especially for people living with diabetes. These wounds often refuse to heal, cause constant pain, and invite dangerous infections that resist antibiotics. Doctors struggle to treat them, and patients can feel trapped in a cycle of care that never seems to end. New research now points to a surprising helper in this fight: ordinary sunlight.

A team of scientists has developed a nanospray that uses natural light to kill bacteria, stop bleeding, ease pain, and speed healing, all at once. The work focuses on diabetic foot ulcers, one of the most serious and common chronic wounds. The findings suggest a future where treating infected wounds becomes simpler, less painful, and far more accessible.

The study describes a new material called SPS, short for sunlight powered spray. It is made from tiny self assembled particles that combine a near infrared light sensitive compound with chitosan oligosaccharides, a substance derived from natural sugars. When sunlight hits the spray, it activates a powerful response that targets infection and supports healing, while staying inactive in the dark for safety.

Chronic wounds, especially those linked to diabetes, form when the body loses its normal ability to repair itself. High blood sugar reduces circulation and weakens immune defenses. Bacteria can settle in, forming infections that linger for months. These wounds often stay open, bleed easily, and cause ongoing pain.

Standard treatments include antibiotics, dressings, and sometimes surgery. Photodynamic therapy has also shown promise. This method uses light to activate drugs that kill bacteria. Yet it often requires lasers, special lamps, and trained staff. The light can cause pain, and the equipment is costly. These barriers limit its use, especially outside hospitals.

The new SPS approach aims to remove those obstacles. Instead of lasers, it relies on sunlight. Instead of repeated drug doses, it uses a single spray that activates only where light reaches it.

The heart of the SPS system is a near infrared photosensitizer that reacts to light. When sunlight activates it, the compound produces reactive oxygen species. These are highly active molecules that damage bacterial membranes and kill microbes quickly.

Laboratory tests showed that SPS under sunlight killed bacteria more effectively than vancomycin, a powerful antibiotic often used as a last resort. This included methicillin resistant Staphylococcus aureus, commonly known as MRSA. In the dark, SPS remained inactive, which reduced the risk of harming healthy tissue.

Microscopy images revealed what was happening at the cellular level. After treatment, bacterial cell walls were ruptured and destroyed. This confirmed that the spray worked through direct physical damage to the bacteria, not through slow chemical signaling.

Chitosan oligosaccharides added another layer of benefit. This natural material is known to support wound healing. It promotes clotting, reduces inflammation, and has mild antibacterial effects of its own. Together, the light activated compound and the chitosan coating formed a multifunctional therapy in a single spray.

In open wounds, bleeding is a serious concern. The researchers tested SPS in animal bleeding models to see how well it controlled blood loss. Under sunlight, the spray reduced bleeding time and total blood loss significantly compared with untreated wounds. This rapid hemostatic effect is critical for chronic wounds that reopen easily.

Pain relief turned out to be another major advantage. Chronic wounds often cause constant discomfort that limits movement and sleep. In mouse studies, animals treated with SPS and sunlight showed much lower sensitivity to touch. Their pain responses dropped close to normal levels.

Further tests looked inside the nervous system. The treatment reduced activity in pain related ion channels, including those involved in heat and mechanical sensitivity. It also helped restore normal nerve signaling patterns in the spinal cord. These changes explained why the animals experienced less pain without the use of traditional pain medications.

The most striking results came from tests on infected diabetic wounds. Researchers created wound infections in diabetic animal models and treated them with SPS under sunlight. Over time, these wounds closed much faster than those in control groups.

The treated wounds showed healthier tissue growth and stronger collagen formation. Collagen is essential for skin strength and structure. The balance of collagen types shifted toward patterns seen in normal healing, not chronic inflammation.

Inflammation markers in blood and wound tissue also dropped sharply. Levels of proteins linked to swelling and immune stress fell to a fraction of those seen in untreated wounds. This calmer environment allowed the body to rebuild tissue more effectively.

Importantly, safety tests raised no red flags. Blood tests remained normal. Major organs showed no signs of damage. Cells exposed to SPS in the lab stayed healthy. The spray did its work locally and then faded, leaving surrounding tissue unharmed.

The simplicity of the approach stands out. Sunlight replaces expensive machines. A spray replaces complex drug regimens. This could change wound care in clinics, homes, and emergency settings.

Because the treatment does not rely on antibiotics, it avoids contributing to drug resistance. That matters as antibiotic resistant infections continue to rise worldwide. The painless nature of the therapy also improves patient comfort and cooperation.

The researchers note that sunlight availability can vary. Weather, location, and time of day matter. Even so, the spray responds to low intensity light and does not require perfect conditions to work.

This sunlight powered nanospray could transform how chronic infected wounds are treated, especially diabetic foot ulcers. It offers a way to kill resistant bacteria, stop bleeding, reduce pain, and speed healing in one step.

The approach could benefit patients in remote or resource limited areas where advanced equipment is unavailable. It also supports home based wound care, reducing hospital visits and costs.

For research, the study opens new paths in photodynamic therapy design. It shows that natural light can drive advanced medical treatments safely. Future work may adapt the platform for burns, surgical wounds, and other infections.

If tested successfully in humans, this therapy could improve quality of life for millions of people and reduce the global burden of chronic wounds.

Research findings are available online in the journal National Science Review.

The original story "New sunlight-powered nanospray heals infected diabetic wounds" is published in The Brighter Side of News.

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