Scientists achieve unprecedented control of active substances
An international research team led by Brandeis University has made significant advances in the field of active matter physics, as detailed in a study published this week in Physical Review X. This pioneering work provides the first experimental validation of important theoretical predictions regarding 3D active materials. It is produced by confining nematic liquid crystals within cell-sized spherical droplets.
Nematic liquid crystals, made up of elongated molecules aligned in the same direction, have revolutionized modern technology, especially in liquid crystal displays (LCDs) used in smartphones and computer screens. Controlling the molecular orientation of these materials enables the vivid displays we use every day.
In active nematic liquid crystals, molecules expend energy to propel themselves. These active materials exhibit dynamic, living-like behavior, including spontaneous deformation and flow, even without the application of external forces. Examples of active nematics include bacterial biofilms, cancer cells, and even rice grains on a diaphragm.
Previous experimental studies have shown that 3D active nematics often exhibit chaotic dynamics. But the seminal active matter theory predicts that at low energy levels or strong confinement, these materials should stop moving. A new study showed that by trapping these substances within cell-sized droplets, their chaotic self-stirring motion can indeed be halted.
“This moment reminds us of the early days of LCD technology,” says Dr. Salman Alam, lead author of the study. “We have succeeded in controlling and stabilizing active liquid crystals that convert chemical energy into motion, similar to the way our cells operate. This control of active chaos is important for these materials. It is extremely important for future engineering applications.”
The researchers mixed bundles of microtubules, a biological macromolecule important for cell division, with motor proteins and oil to create an emulsion that is an active analog of the oil-water mixture found in vinaigrette.
“Entrapping these materials in cell-like droplets was a game changer,” explains Guillaume Duclos, Ph.D., assistant professor of physics at Brandeis University and corresponding author. “Our team has been trying to test this fundamental prediction of active matter theory for years, and to have such a seamless alignment between theory and experimental results is truly extraordinary. ”
International cooperation proved essential to the success of the research. Dr. Abhinav Singh from the Dresden University of Technology, the Max Planck Institute for Molecular Cell Biology and Genetics, and the Dresden Center for Systems Biology led the theoretical research and simulations.
“The agreement between our theoretical predictions and experimental results is remarkable,” said Dr. Singh. “This confirms the fundamental behavior of active materials, advances our understanding of living systems, and may open the door to new nanotechnology innovations.”
This research is important for understanding a variety of biological processes, from the alignment of cells within tissues to mitotic spindle organization during cell division.
“This research not only confirms the theory, but also paves the way for advances in materials science and soft robotics,” says the Department of Theoretical Physics at Brandeis University and the Brandeis Bio-Inspired Materials Research Science and Engineering Center (MRSEC). Professor Aparna Bhaskaran, director of -Author of this study. “We are expanding our understanding of the laws of life, and the boundaries between matter and life are becoming blurred.”
Gaining control over active biopolymers could lead to advances in artificial cells, self-healing materials, and biomedical applications. For example, this study could help us understand how to prevent the uncontrolled spread of metastatic cancer cells and bacterial biofilms, two well-characterized examples of activated nematics.
As the field of active materials physics reaches this milestone, researchers are already exploring future applications. “We are on the brink of a new era in materials science at the intersection of biology, physics, and engineering,” Dr. Duclos concluded. “Our research aims to foster innovation in active materials research and applications with building materials with life-like properties.”
Further information: Salman Alam et al., Active Fréedericksz Transition in Active Nematic Droplets, Physical Review X (2024). DOI: 10.1103/PhysRevX.14.041002
Provided by Brandeis University
Citation: Scientists Achieve Unprecedented Control of Active Substances (October 4, 2024) Retrieved October 6, 2024 from https://phys.org/news/2024-10-scientists-unprecedented.html
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