Control of filament network rigidity by the condensation of crowding molecules
Abstract
Understanding how liquid-liquid phase separation impacts the mechanics of filament networks is a fundamental physical problem at the heart of biological cellular processes and soft material design. While a few theoretical mechanisms have been proposed, a clear demonstration of the direct coupling of phase separation to the overall network stiffness is missing. We report experiments that reveal a universal mechanism by which the condensation of macromolecular crowders induces a rigidity transition in a model filament network. We reconstituted stiff sterically interacting helical filaments and polymeric crowders. Initially, the macromolecules were uniformly dissolved and the filaments formed bundles that assembled a rigid entangled network. Once the crowders condensed into droplets, the network structure lost its rigidity and its mechanical response weakened by an order-of-magnitude. The subsequent dissolution of the condensates was accompanied by the re-establishment of rigidity. Our results show that crowder phase separation modulates the mechanics of filament networks by tuning the osmotic pressure holding the network together. This principle may serve as a paradigm for devising dynamically tunable filamentous materials.
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BibTeX
@misc{cheon2026control,
title = {{Control of filament network rigidity by the condensation of crowding molecules}},
author = {Jiyong Cheon and Zhengyan Lin and Dean Kim and Anirudh Malli and Itamar Kolvin},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26983},
eprint = {2609.26983},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26983},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Control of filament network rigidity by the condensation of crowding molecules
AU - Jiyong Cheon
AU - Zhengyan Lin
AU - Dean Kim
AU - Anirudh Malli
AU - Itamar Kolvin
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.26983
UR - https://arxiv.org/abs/2609.26983
AB - Understanding how liquid-liquid phase separation impacts the mechanics of filament networks is a fundamental physical problem at the heart of biological cellular processes and soft material design. While a few theoretical mechanisms have been proposed, a clear demonstration of the direct coupling of phase separation to the overall network stiffness is missing. We report experiments that reveal a universal mechanism by which the condensation of macromolecular crowders induces a rigidity transition in a model filament network. We reconstituted stiff sterically interacting helical filaments and polymeric crowders. Initially, the macromolecules were uniformly dissolved and the filaments formed bundles that assembled a rigid entangled network. Once the crowders condensed into droplets, the network structure lost its rigidity and its mechanical response weakened by an order-of-magnitude. The subsequent dissolution of the condensates was accompanied by the re-establishment of rigidity. Our results show that crowder phase separation modulates the mechanics of filament networks by tuning the osmotic pressure holding the network together. This principle may serve as a paradigm for devising dynamically tunable filamentous materials.
ER -