Rice University scientists have figured out new ways to control engineered living materials (ELMs), which are materials made by living cells. They have looked at how changing protein structures changes how these materials act when stretched or squeezed.

The scientists worked with a bacterium called Caulobacter crescentus, modifying its genes to produce different versions of a protein called BUD. This protein helps cells stick together, forming a supportive network or matrix.

The scientists have described the methods and results of this study in a paper published in ACS Synthetic Biology.

Building living materials from the ground up

By tweaking the length of protein parts called elastin-like polypeptides (ELPs), the scientists made three types of materials: BUD40, BUD60, and BUD80.

BUD40 has short ELPs, making thick, stiff fibers. BUD60, with medium-length ELPs, combines globules and fibers for strong, adaptable material. BUD80’s long ELPs create thin, less stiff fibers that break easily under stress.

These changes affect how the materials respond to stress and flow under pressure. BUD60, for example, handles force well and adapts to environmental changes, perfect for uses like 3D printing or controlled drug delivery.

All these materials share two traits: they become less viscous when sheared (shear-thinning) and are 93% water by weight. This makes them good for medical applications like tissue scaffolds or drug delivery systems.

“We are engineering cells to create customizable materials with unique properties,” said Caroline Ajo-Franklin in a Rice press release. “While synthetic biology has given us tools to tweak these properties, the connection between genetic sequence, material structure and behavior has been largely unexplored until now.”

In summary, the scientists have built living materials from the ground up with tailored mechanical properties.

This study shows how small genetic changes can lead to big changes in material properties. This opens up possibilities in fields like tissue engineering, drug delivery, and even beyond to environmental or energy applications.

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