Mechanism that helps active systems to escape transformation to glass can aid study of cancerous metastasis: Scientists

When a liquid is super cooled, the particles in the liquid slow down drastically, and on further decreasing the temperature, the molecules stop moving altogether and transform into a glass. Pragya Arora, Prof Rajesh Ganapathy from JNCASR and Prof Ajay K Sood from IISc, who studied the glassy dynamics of an artificial active-matter system, found that patterns can form in systems consisting of active elongated particles that help it elude from turning glassy.

Their research published in the journal Physical Review Letters showed that the patterns were triggered by the defects in the orientation of the particles and this helped keep the particles moving, preventing the system from behaving like a typical glass. They have now identified the mechanism that helps such active matter particles where the individual constituents are elongated in shape, elude turning glassy. This mechanism that helps active systems escape transformation to glass can aid study of cancerous metastasis.

“The assemblies of active elongated particles spontaneously coalesce into beautiful swirls, a technique that keeps them from freezing into the glassiness. The swirls are mediated by the defects in the packing. Since such motile defects are known to play a role in the human body’s defence against precancerous, abnormal cells, this study could provide a tool for probing cancerous metastasis,” the researchers said.

“With an aim to develop well-controlled experiments with a synthetic active matter where activity can be tuned systematically while keeping the particle shape features fixed, the team from JNCASR, chose a system of vibrated granules for their experiment. They used millimetre-sized ellipsoidal particles fabricated by 3-D printing, made self-propelled by vertical vibrations. The researchers had found in earlier studies that particles with an asymmetry in their shape, mass, and/or friction coefficient along the two ends would become active or self-propelled under vibration,” DST said.

“Building on these results, they made particles with one end rougher than the other to include friction differences. They also included a hole in the print process to increase the mass asymmetry between the two sides and tuned the particle activity by changing its centre of mass by playing with the position of the hole. Arora and her colleagues found that at higher particle densities, most active particles spontaneously coalesced into swirls,” it added.

According to Arora, cellular systems have several biological functions, such as cell death, extrusion, tissue regeneration and sorting, which show active behaviour. This study can shed light on these fundamental biological processes where these motile defects are critical players.