A Light-Powered Graphene Coat That Kills Germs

Graphene is a special material made of just one thin layer of carbon atoms. It is much stronger than steel but lighter than aluminum. Scientists found a new way to use it to kill germs. They made a special coating that only needs a small bit of light. When light touches the graphene, it starts a chemical reaction. This reaction creates special molecules that destroy tiny harmful microbes. These microbes include bacteria, viruses, and fungi that make people sick.

Giacomo Reina is a scientist at EMPA in Switzerland. His team shared the news about this material last year. They published their findings in a journal called EcoMat. As a liquid, this substance can coat many hard surfaces. It could cover doorknobs or handrails in hospitals. However, the team wants to use it in the human mouth first. This place often has many germs that cause infections. New dental implants sometimes get infected after surgery. Coating the implant with this germ-fighting material could lower that risk.

Scientists discovered graphene twenty-two years ago. Since then, they have used it in many different ways. It can strengthen concrete and make tennis rackets better. It also helps improve electronic devices for our homes. Now, graphene is like a family of many materials. Reina's team used a type called graphene oxide. This is a carbon layer with oxygen molecules attached to it. The formula mixes with water to form a mild acid.

The team added a small amount of nitrogen to the acid. Scientists call adding extra ingredients to a material doping. So, this new substance is called nitrogen-doped graphene acid. Making it requires very high precision to be perfect. Unplanned defects can make the material useless for use. The added nitrogen helps keep the material stable and strong. "When I saw this material, I fell in love," Reina says. He wanted to see if it would work as a germ killer.

When light hits the doped material, it changes in two ways. First, the material gets warm, and this heat kills some microbes. The light also causes a reaction with oxygen in the air. This creates microbe-fighting molecules called radicals. Turning the material into a liquid coating took over a year. The scientists asked many questions about how light interacted with it.

Reina's group mixed the material with bacteria in the lab. They found it could kill germs in infrared light. These wavelengths are found in both sunlight and room lights. They also tested it on a chemical that looks like skin. It caused no harmful reactions to the test material. These tests show the material is safe for the human body. This safety is critical for how they plan to use it.

The team is working with dentists to make a special splint. It is a tray filled with a clear liquid film. The film fits over teeth to protect them well. Within minutes, the tray coats teeth with the new material. Then, light shined into the mouth turns on the germ killing. The researchers are testing it against germs in gum tissue. One day, patients might wear the splint after a procedure. They could expose it to light to kill harmful germs. Reina sees this as a new tool against superbugs. Some germs have become resistant to drugs like antibiotics. These infections are hard to stop and very dangerous. Materials like graphene deliver a two-part attack on germs.