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Shedding light into mechanics of biological systems

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Published on Thursday, 10 February 2022

An interdisciplinary research article published in Nature Communications provides novel insights into collective mechanical forces induced by light absorbed in biological systems. This research is a result of collaboration between the Universities of Luxembourg, Manchester and Padova.

Interactions between light and matter

Light-matter interactions are essential for living systems and industrial applications. Fundamental processes such as vision, photosynthesis, and photovoltaic energy conversion, all rely on concerted and selective interactions between light and matter. While photon energy transfer to electrons is well understood, light can also activate collective mechanical motions. The latter process is poorly understood at the moment because of its complex quantum mechanical nature that is difficult to model and understand for realistic molecular systems that contain thousands or millions of atoms.

Novel insights 

The advance of the interdisciplinary team included developing efficient methodology that allows to model light-induced forces in systems with tens of thousands of atoms, enabling the modeling of arbitrary nanostructures, molecular materials, and biomolecules. Remarkably, it was found that both attractive and repulsive mechanical forces can arise upon interaction of molecules with light, opening new perspectives for the control and activation of dynamical processes by light.

Moreover, a comprehensive analysis of the human formaldehyde dehydrogenase protein revealed both localised and delocalised mechanical deformations that sensitively depend on the photon energy. Low photon energies were found to activate local deformations, whereas more energetic photons can induce large-scale motions of the protein. Hence, these calculations rationalise the recent experimental observation of efficient energy transfer between absorbed light and collective mechanical vibrations.

"This work presents a breakthrough result deriving from a long-term collaboration between Padova and Luxembourg, aiming to address complex dynamical phenomena in biology. The complex dynamical order required for the functionality of living cells is expected to depend on long-ranged selective forces that are yet to be understood. What we found here is one of the possible light-matter interaction mechanisms that can selectively activate large-scale mechanical vibrations in large biomolecules", says Dr. Alberto Ambrosetti from the University of Padova.

"Understanding light-matter interactions in complex molecular systems is one of the most fundamental contemporary challenges in physics, chemistry, and biology. Our work proposes an efficient methodology that enables a practical and accurate treatment of photon-induced mechanical vibrations in large molecules. The shown applications highlight the high potential of our methodology to study a wealth of novel phenomena previously inaccessible to computational modeling", says Prof. Alexandre Tkatchenko, from the Department of Physics and Materials Science at the University of Luxembourg.

Full paper available here