17 Feb. Functional coating makes UV-A radiation visible
Researchers at the Technical University of Munich (TUM) have developed a coating based on proteins and bacteria that can reliably detect exposure to UV-A radiation. The protein mEosFP changes its color from a green shade called “Vegan Villain” to a red tone named “End of Summer.” This color transition makes it particularly suitable for use in UV-A sensors that indicate when specific UV levels have been reached. Until now, however, it has remained unclear how such proteins can be stably and functionally integrated into paints and coatings without compromising their material properties.
A team led by Volker Sieber, Professor of Chemistry of Biogenic Resources and Rector of the TUM Campus Straubing, has now developed a sustainable and bio-based alternative to conventional UV-A sensors, which typically rely on fossil resources such as oil and coal. According to the researchers, this breakthrough could serve as a blueprint for further advances in the emerging field of so-called living or biohybrid materials, which aim to combine the strengths of biology and technology. Their goal is to integrate biological organisms such as fungi, algae, proteins, or bacteria into materials in ways that enable them to self-repair, regenerate, or respond to external stimuli.
Color intensity depends on duration of exposure
For the study, the team cultivated the desired protein using E. coli bacteria. “The bacteria appear to act as a kind of protective environment for the proteins, shielding them from chemical and physical influences within the formulation,” explains Amelie Skopp, a member of the research team.
The color change begins after just a few minutes of irradiation, becomes clearly visible after 15 minutes, and is fully completed after about one hour, the researchers report. The stronger the UV-A exposure, the more intense the resulting color. Potential applications for UV-A sensors include the storage and transport of light-sensitive pharmaceuticals as well as the monitoring of UV disinfection processes.
Samples of the purified protein: In the green sample, the color change has not yet occurred; in the reddish sample, it is clearly visible. Photo: Astrid Eckert / TUM
Sustainable biological dyes for sensors
“We have demonstrated that coatings can be equipped with biological additional functionalities without losing their inherent properties,” says Skopp. She and her colleague Matea Marošević, together with other team members, were recently awarded the TUM IdeAward for a startup concept aimed at further developing this technology. The team is currently working on a bio-based filter technology capable of capturing volatile organic compounds and converting them into harmless substances.
Biological systems offer an enormous diversity of functions that can be harnessed, explains Sieber. “The potential range extends from materials like ours, which make environmental conditions visible, to future solutions capable of capturing and degrading hard-to-avoid greenhouse gases such as methane from the air,” says the scientist. “Successfully stabilizing biological components within coatings is an important starting point for developments that we urgently need in light of today’s global challenges.”
Original publication:
[A. Skopp, M. Marošević, B. Rühmann, and V. Sieber: The Vegan Villain sets out to the End of Summer: Functionalized coatings as biohybrid UV-sensors; Adv. Mater. Interfaces (2025). https://doi.org/10.1002/admi.202500125]
Source: www.tum.de
Images: Astrid Eckert / TUM