Exerting pulling forces in fluids by directional disassembly of microcrystalline fibres

• Published in: Nature nanotechnology Vol. 19; no. 10; pp. 1507 - 1513
• Main Authors: Pantaleone, L. C., Calicchia, E., Martinelli, J., Stuart, M. C. A., Lopatina, Y. Y., Browne, W. R., Portale, G., Tych, K. M., Kudernac, T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.07.2024; Nature Publishing Group
• Subjects: 140/133; 639/638/541; 639/638/541/960; Chemical potential; Chemistry and Materials Science; Coumarin; Crystal lattices; Crystal pulling; Crystal surfaces; Dismantling; Etching; Fibers; High aspect ratio; Materials Science; Microfibers; Monomers; Nanotechnology; Nanotechnology and Microengineering; Polymerization; Spectroscopy
• ISSN: 1748-3387; 1748-3395; 1748-3395
• DOI: 10.1038/s41565-024-01742-x

Biomolecular polymerization motors are biochemical systems that use supramolecular (de-)polymerization to convert chemical potential into useful mechanical work. With the intent to explore new chemomechanical transduction strategies, here we show a synthetic molecular system that can generate forces via the controlled disassembly of self-organized molecules in a crystal lattice, as they are freely suspended in a fluid. An amphiphilic monomer self-assembles into rigid, high-aspect-ratio microcrystalline fibres. The assembly process is regulated by a coumarin-based pH switching motif. The microfibre crystal morphology determines the monomer reactivity at the interface, resulting in anisotropic etching. This effect exerts a directional pulling force on microscopic beads adsorbed on the crystal surface through weak multivalent interactions. We use optical-tweezers-based force spectroscopy to extract mechanistic insights into this process, quantifying a stall force of 2.3 pN (±0.1 pN) exerted by the ratcheting mechanism produced by the disassembly of the microfibres. Disassembling molecular microcrystalline fibres produce mechanical work by dragging micro objects along their surface via biased diffusion.