Simply Eliminate Germs With Light

Research Simply Eliminate Germs With Light

2025-10-01 Source: Empa | Translated by AI 2 min Reading Time

Lights on—bacteria dead. Disinfecting surfaces could be that simple. To turn this idea into an effective weapon in the fight against antibiotic-resistant pathogens, Empa researchers are developing a coating whose germicidal effect can be activated with infrared light.

Biocompatible: Stably and safely embedded in a biocompatible plastic, graphene acid proves lethal to germs.(Image: Empa) — Biocompatible: Stably and safely embedded in a biocompatible plastic, graphene acid proves lethal to germs.
(Image: Empa)

Bacteria resistant to antibiotics and newly emerging viruses pose an increasing threat to the global healthcare system. Empa researchers are therefore working on new, urgently needed strategies to combat such pathogens. One of the goals: to prevent the spread of resistant pathogens and novel viruses with smart materials and technologies.

Near-Infrared Light Activates Effect

A particularly suitable application for such materials is on surfaces that are constantly in contact with infectious agents, such as door handles in hospitals or furniture in operating rooms. An interdisciplinary team from three Empa laboratories, in collaboration with the Czech Palacký University Olomouc, has now developed an environmentally friendly and biocompatible surface coating made of plastic that reliably kills germs. The highlight: its effect can be reactivated repeatedly through exposure to light.

Graphene Acid As An Antimicrobial Coating

The new material is based on a framework of polyvinyl alcohol, a biocompatible plastic also used in the food industry. Embedded in this matrix is a specially synthesized graphene acid, which is highly suitable as an antimicrobial coating due to its chemical properties. Its full potential is realized through the use of near-infrared light: once the composite material is irradiated, it deploys its dual strategy:

On the one hand, it absorbs the energy of infrared light and converts it into germicidal heat.
On the other hand, it stimulates the formation of oxygen radicals, which cause additional damage to the pathogen.

Another advantage of this strategy is that it completely differs from the mechanisms of conventional antibiotics. This allows the material to offer continuous protection against a wide range of microorganisms without contributing to the development of resistance.

Red Light in the Oral Cavity

A first application for the antimicrobial coating is currently being developed for dentistry. For this purpose, Empa researchers are working together with the Center for Dental Medicine at the University of Zurich on a dental splint that kills microorganisms in the oral cavity.

The microbial flora in the mouth is a particularly troublesome adversary in the fight against infectious agents: here, complex bacterial communities thrive in inaccessible niches, embedded in a self-produced slimy matrix. Antibiotics and disinfectants hardly penetrate these resilient biofilms. As a result, the germs can continue to damage teeth unchecked or even lead to widespread infections in the body. The interdisciplinary team led by Giacomo Reina is therefore working on a plastic aligner in which nanomaterials, such as graphene acid, are stably integrated. Since near-infrared light can penetrate tissue several centimeters deep, the aligner can be placed in the oral cavity and activated externally by a light source—repeatedly.

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Date: 08.12.2025

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