Supramolecular machineries with life-like mechanical functions

Project Information

MechanoTubes

Grant agreement ID: 819075

DOI

10.3030/819075

Project closed

EC signature date 21 December 2018

Start date 1 March 2019

End date 31 December 2024

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 2 000 000,00

EU contribution

€ 2 000 000,00

Coordinated by

RIJKSUNIVERSITEIT GRONINGEN
Netherlands

Periodic Reporting for period 4 - MechanoTubes (Supramolecular machineries with life-like mechanical functions)

Reporting period: 2023-04-01 to 2024-12-31

Summary of the context and overall objectives of the project

Artificial molecular machines have the potential to become a core part of nanotechnology. However, a wide gap in length scales remains unaccounted for, between the operation of these molecules in solution, where their individual mechanical action is randomly dispersed in the Brownian storm, and on the other hand their action at the macroscopic level, e.g. in polymer networks and crystals. Bridging this gap, requires chemo-mechanical transduction strategies that will allow dynamic molecules to perform a range of unprecedented tasks, e.g. by generating strong directional forces at the nanoscale and in fluid environment. Showing the way for synthetic systems, biological machinery has emerged from the pool of dynamic biomolecules operating in fluid environment. The key strategy that nature uses to overcome the Brownian storm and perform useful mechanical work is to connect the dynamics of individual biomolecular building blocks with the self-assembly processes. Such molecular machineries operating at the level of the self-assembly processes are known as polymerisation and depolymerisation motors. Developing synthetic mechanically active molecular systems that operate on the same principles constitutes the next major challenge in the field of artificial molecular machines.
In this project, we address conceptual aspects of these challenges. The key strategy is to use molecular self-organization as means of generate mechanical force. To do so we draw inspiration from the operational principles of cellular microtubules. By incorporating photo-switches into the design of the molecular monomers we enable the controlled growth and disassembly of the tubes by using light as the energy input. The specific strategy to gain new knowledge and reach these goals consist of: (i) Synthesizing stiff supramolecular tubes made of molecules that grow actively under continuous illumination, and disassemble as soon as illumination stops; (ii) Measuring, and harvesting the forces generated by the tubes to manipulate individual nanoparticles with a sense of directionality; and (iii) Encapsulating the tubes into water droplets and vesicles, to yield shape-shifting, and eventually rudimentary splitting models for cells.
This project will lay the foundations for machineries that are capable of manipulating matter at length scales that are also those at which the cytoskeleton operates.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Over the course of this project, we have made several breakthroughs in designing and understanding mechanically active supramolecular systems. Together, these achievements establish the foundations of a new field where artificial molecular assemblies can generate, transmit, and withstand mechanical forces in fluid environments, ultimately mimicking and complementing the functional roles of cytoskeletal polymers.

1. Interfacing and crosslinking self-assembled tubes
To harness mechanical forces effectively, supramolecular fibers must be connected to the structures on which they act. We developed strategies for interfacing and crosslinking tubular assemblies, thereby amplifying the collective action of multiple molecular machines. These insights also advance the broader understanding of crosslinking and interaction in supramolecular polymers, with implications for soft materials design.

2. Light-fuelled self-assembly into tubular architectures
We established non-equilibrium self-assembly pathways where tubular supramolecular polymers are maintained in dynamic steady states driven by light. These assemblies undergo rapid cycles of growth and disassembly, operating at rates sufficient to generate mechanical work in fluid. This demonstrates that supramolecular systems can be fuelled and controlled externally to emulate the dynamic behavior of cytoskeletal filaments.

3. Mechanical properties of supramolecular hydrogel networks
We explored the mechanical properties of stiff tubular fibers assembled into hydrogels. These networks exhibit strain stiffening under stress, analogous to collagen and fibrin, followed by plastic deformation that preserves network integrity. This discovery of structural plasticity in purely supramolecular systems provides a new paradigm for designing adaptive and resilient biomimetic materials.

4. Depolymerization motors as microscopic machines
We realized the first artificial depolymerization motors, capable of exerting mechanical forces through directional disassembly. These forces are sufficient to drag microscopic particles against fluid flow, directly paralleling the role of microtubules during cell division. This achievement represents one of the first demonstrations of a synthetic microscopic machine performing work in fluid, opening the way toward molecular robotics and programmable manipulation of matter at the microscale.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Our project has advanced the state of the art by demonstrating that supramolecular systems can generate, transmit, and adapt to mechanical forces in ways previously thought exclusive to biological polymers. We established the first artificial depolymerization motors capable of performing mechanical work in fluids, directly paralleling microtubule-driven chromosome transport during cell division. We also discovered structural plasticity in supramolecular hydrogels, a property unprecedented in synthetic systems, enabling materials that stiffen under load yet adapt through permanent structural rearrangements. In addition, we developed fuel-driven, light-controlled self-assembly of tubular architectures and strategies for interfacing and crosslinking supramolecular polymers, laying the foundations for programmable molecular mechanics.

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