Rice University researchers have made a significant breakthrough in the field of engineered living materials (ELMs), revealing a novel method to precisely control their structure and response to forces like stretching or compression. This discovery, published in a special issue of ACS Synthetic Biology, could revolutionize various fields, including tissue engineering, drug delivery, and even 3D printing of living devices.
The research focused on modifying protein matrices, the networks of proteins that provide structure to ELMs. By introducing small genetic changes, the team discovered they could significantly alter the behavior of these materials. The researchers used a bacterium called Caulobacter crescentus, engineered to produce a protein called BUD, which helps cells stick together and form a supportive matrix.
The team then varied the length of specific protein segments called elastin-like polypeptides (ELPs) within the BUD-ELMs, creating three distinct variants: BUD40, BUD60, and BUD80. Each variant exhibited unique properties based on the length of its ELPs. BUD40, with the shortest ELPs, formed thicker fibers, resulting in a stiffer material. BUD60, with mid-length ELPs, created a combination of globules and fibers, producing the strongest material under deformation oscillation stress. BUD80, with the longest ELPs, generated thinner fibers, leading to a less stiff material that breaks easily under deformation stress.
Advanced imaging and mechanical tests revealed that these differences were not merely cosmetic but fundamentally affected how the materials handled stress and flowed under pressure. BUD60, for example, could withstand more force and adapt better to changes in its environment, making it ideal for applications like 3D printing or drug delivery.
All three materials shared two key characteristics: they exhibited shear-thinning behavior, meaning their viscosity decreased under stress, and they retained a high amount of water (about 93% of their weight). These properties make them well-suited for biomedical uses such as scaffolds to support cell growth in tissue engineering or systems for delivering medications in a controlled way.
The potential applications extend beyond the biomedical field. These self-assembling materials could be adapted for environmental cleanup or renewable energy applications, such as building biodegradable structures or harnessing natural processes to generate energy.
This research, supported by the National Science Foundation Graduate Research Fellowship, the Cancer Prevention and Research Institute of Texas, and the Welch Foundation, emphasizes the importance of understanding the relationship between genetic sequences, material structure, and behavior. By identifying how specific genetic modifications affect material properties, researchers are building a foundation for designing next-generation living materials.