Spacecraft interiors are a specific environment with high requirements. In order to ensure the safety of astronauts against the proliferation of pathogenic agents, such as bacteria or parasites, antimicrobial surface treatments are applied to the various interior surfaces of the spacecraft. Although effective solutions are already in use, the scientific community has nevertheless proven their long-term toxicity risk due to their composition based on heavy metal particles.
Selected by the European Space Agency (ESA) in 2019 to develop new non-toxic antimicrobial surface treatments in the frame of the project NBactSpace (ESA AO/1-9363/18/NL/KML), David Duday and the project team have developed new approaches that are proving to be as effective as existing commercial solutions but researchers have succeeded in replacing commonly used heavy metal particles with non-toxic bio-based materials.
"Just like commercial samples, we were able to reduce bacterial activity by about 6 levels of magnitude. In other words, it is as if we went from 100 million bacteria to 100 bacteria", explained David, researcher at LIST and leader of this project. But these promising results don't stop there! Through various tests, the researchers have managed to demonstrate the non-cytotoxicity and durability of their coating.
The coatings developed at the department of Materials Research and Technology of LIST are the results of a cross expertise in chemistry, materials, surface treatment and analysis, durability tests, microbiology and toxicology. These unprecedented surface treatments prove a strong capacity to inactivate two major families of bacteria (Gram + and Gram -), which are the cause of many infections. "As these bacteria are found in space as well as on Earth, the scope of this innovation made by LIST could extend far beyond the aerospace field", detailed David.
Researchers are now adapting their deposit to have a combined effect on a third type of pathogen: filamentous fungi of type A. niger or yeasts of type C. albicans. Radically different from bacteria, these pathogens are more difficult to inactivate due to their more complex structure. During the last months of this project, David and the project team are therefore hoping to move from a coating with antibacterial properties to an antimicrobial coating.
In an effort to provide a marketable approach, the researchers will subsequently optimise their coating by treating larger and then more complex commercial objects in a future project. "To date, we have been able to validate our results on a surface area of 30/20 cm2. Our aim now is to achieve the same efficiency on 3D objects and much larger surfaces”, concluded David.