Single Chain Polymer Condensates under External Force

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Contributors

Abstract

We investigate the behavior of a single chain condensate formed through polymer-assisted condensation (PAC) [ Sommer, J.-U. . Macromolecules 2022, 55, 4841-4851] under the influence of an external force using molecular dynamics simulations and mean-field theory. By pulling at the chain ends we observe a first-order phase transition at a critical force, characterized by the coexistence of the condensate and stretched segments of the chain at a fixed deformation. We develop a free energy model capable of accommodating the deformed droplet state and the overstretched chain segments. This enables us to calculate the condensation free energy and the surface tension of the condensate formed by phase separation of the two-component solution induced by the polymer, across various compositions of the solvent mixture. We demonstrate the feasibility of matching a Flory-Huggins-type mean field model to Lennard-Jones fluid simulations. A numerical analysis of this Lennard-Jones equivalent model reveals the scaling behavior of the condensation free energy of the PAC-droplet with respect to the chemical potential of the cosolvent and the interaction energy between the cosolvent and the monomers. We discuss the calculated surface tension for a protein model of the cosolvent. This study is poised to advance our understanding of the physical properties exhibited by biomolecular condensates, particularly those formed on DNA under external tension, by considering DNA-binding proteins as cosolvent particles.

Details

Original languageEnglish
Pages (from-to)9476-9488
Number of pages13
JournalMacromolecules
Volume57
Issue number19
Publication statusPublished - 8 Oct 2024
Peer-reviewedYes