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Morphogenesis of photo-mechanized molecular materials

Periodic Reporting for period 2 - Morpheus (Morphogenesis of photo-mechanized molecular materials)

Reporting period: 2020-04-01 to 2021-09-30

The evolution of humanity is inherently connected to the materials we can make and use. So much, that our history is divided into technological eras – each of them starting with a breakthrough in materials science. However, each of these eras is disappearing faster than the previous one, and silicon is not the drive for innovation that it used to be anymore. Intelligent and life-inspired materials could embody a paradigm shift, because in biological materials, the material is the device itself, which also means less waste, and more adaptability.

Morpheus aims at designing life-like and adaptive materials that are inspired from morphogenesis.

The Volvox algae is a simple model for morphogenesis – a spherical sheet of cells, that form a colony and work together. During morphogenesis, Volvox undergoes a dramatic shape transformation: it turns inside out, thus revealing flagella, and then, it starts turning. Three key design principles underpin such a tissue deformation: i) There is an active deformation of individual, spherical soft units that is driven by molecular machines ii) The individual units are interacting through connective dynamic junctions; iii) and the shape changes of each unit are transmitted by anisotropy in the environment, across increasing length scales. The specific objective of Morpheus is to bring about a new concept towards sustainable man-made materials, by re-engineering each of these morphogenetic design principles, first independently and then as a combination, in synthetic soft matter.
My approach consists in incorporating hierarchical structuration in mechanized materials, with a special focus on structural hierarchy and the engineering of anisotropy. This approach is inspired from the principles of shape transformations in living tissues.
1. Mechanizing soft matter with active molecular systems
Morphogenesis requires cells to change shape and collectively, these cellular deformations give rise to tissue transformation. During morphogenesis, the elastic deformation of cellular tissues is driven by the molecular machinery of the cell (the cytoskeleton). This movement requires amplifying the operation of molecular machines in soft matter, across increasing length scales. At mid-term, our published scientific output primarily concerns this aspect of the work, with significant contributions in integrating either artificial molecular machines or molecular knots into anisotropic soft matter. This research has consequences for the design of tissue-like materials and soft robotics.
2. Neuromorphic transformation of spherical building blocks
One of the cellular shape changes we are particularly interested in, is the formation of axons that grow from the body of neurons – typically, networks of neuronal cells grow and connect through synapses as they change shape and grow axons. We research the fundamental physics and chemistry that may be involved in the growth of axon-like features, by using rudimentary cellular mimics. This research on neuromorphic building blocks is relevant to the design of intelligent matter and brain-like systems for neuromorphic computing.
3. Multivalent glues for tissue-like materials
During morphogenesis, molecular machines located at the interface of the cells act as reconfigurable junctions that keep the cells together into a tissue, while allowing the cells to deform actively. These dynamic intercellular bridges are key to the shape-shifting and mechanical properties of cellular tissues. Inspired from these intercellular bridges, we design multivalent supramolecular glues that support strong but reconfigurable adhesion – using either dynamic covalent chemistry, or charged dendrimers. Besides the design of morphogenetic materials, this aspect of the proposal could also contribute to the development of defect-free films of polymer networks.
Dynamic assemblies of active colloids can embody a new paradigm in the development of sustainable materials. This approach is inspired from biological materials, where the building blocks are not so much molecules themselves, but rather supramolecular assemblies or colloids (e.g. a living cell). If more materials are made of the same building blocks, this has also consequences on recyclability of materials. The chemo-mechanical coupling between these building blocks then determines the functionality and dynamics of the material.