Scientists at the University of California, San Diego, have unveiled a pioneering method to broaden the construction possibilities of engineered living materials (ELMs), materials that incorporate living microbes into synthetic matrices. The research, recently published in Proceedings of the National Academy of Sciences, opens new avenues for designing eco-friendly materials capable of environmental cleanup, wound healing, and self-repair.
ELMs typically require biocompatible ingredients to ensure cell survival during material formation. This constraint has limited the types of polymers that can be used. The UC San Diego team, led by Professors Jinhye Bae and Susan Golden, overcame this limitation by introducing a reverse strategy: Inserting the live microbes after the polymer structure has been established.
The researchers demonstrated this by using a temperature-sensitive polymer that contracts at body temperature and expands at room temperature. This swelling behavior allowed photosynthetic cyanobacteria to enter the material after it was formed. Remarkably, once embedded, the bacteria remained functional and even altered the properties of the material, including softening it and inducing permanent shape changes.
Further investigation revealed that the bacteria were releasing an enzyme that partially broke down the polymer, a previously unknown phenomenon. “This unexpected discovery highlights the dynamic nature of materials that incorporate living organisms,” said postdoctoral researcher Nathan Soulier, a co-lead author of the study.
The approach paves the way for using polymers that were once considered too toxic for ELMs, such as those that respond to acidity or conduct electricity. Cyanobacteria are particularly promising, the researchers noted, due to their ability to harness solar energy and be genetically engineered for specific tasks like pollutant removal.
“This innovation gives us a much larger toolkit for designing sustainable materials that work with nature rather than against it,” said Bae. Future work will explore how different polymers interact with these microbes and aim to develop materials that respond to multiple environmental signals.
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