Interfacial Permeability, Reflectivity and Preferential Internal Mixing of Phase-Separated Condensates

Fuente: arXiv
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Hauptverfasser: Joyot, Oihan, Ferrand, Zoé, Muzzopappa, Fernando, Weiss, Pierre, Erdel, Fabian
Format: Preprint
Veröffentlicht: 2026
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author Joyot, Oihan
Ferrand, Zoé
Muzzopappa, Fernando
Weiss, Pierre
Erdel, Fabian
author_facet Joyot, Oihan
Ferrand, Zoé
Muzzopappa, Fernando
Weiss, Pierre
Erdel, Fabian
contents Biomolecular condensates organize biochemical processes by spatially concentrating molecules while allowing for dynamic exchange with their surroundings. However, transport across their interface can be strongly attenuated, leading to enhanced retention and preferential internal mixing. Two key mechanisms have been proposed to describe this behavior: biased interfacial reflectivity, which compares how strongly particles are reflected at the interface when attempting to enter or leave the condensate, and interfacial resistance, which sets the kinetic rate at which particles can cross the interface. Quantifying these parameters experimentally has remained challenging. Here, we present a theoretical and experimental framework to address this issue, extending our previously developed half-FRAP approach. We solve the spherical diffusion problem with a semipermeable interface by spectral decomposition. By evaluating the information content of the integrated recovery curves, we show that they encode sufficient information to recover interfacial parameters over extended regions of parameter space. Applying our framework to tunable coacervates composed of poly-lysine and hyaluronic acid, we find that their interfaces exhibit strongly biased reflectivity and substantial resistance, both driving preferential internal mixing. These parameters depend on salt concentration, linking interfacial transport to intermolecular interaction strength and position in the phase diagram. Our results establish a quantitative connection between interfacial properties and condensate dynamics, revealing how their interplay gives rise to distinct transport regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2603_25447
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Interfacial Permeability, Reflectivity and Preferential Internal Mixing of Phase-Separated Condensates
Joyot, Oihan
Ferrand, Zoé
Muzzopappa, Fernando
Weiss, Pierre
Erdel, Fabian
Biological Physics
Soft Condensed Matter
Subcellular Processes
Biomolecular condensates organize biochemical processes by spatially concentrating molecules while allowing for dynamic exchange with their surroundings. However, transport across their interface can be strongly attenuated, leading to enhanced retention and preferential internal mixing. Two key mechanisms have been proposed to describe this behavior: biased interfacial reflectivity, which compares how strongly particles are reflected at the interface when attempting to enter or leave the condensate, and interfacial resistance, which sets the kinetic rate at which particles can cross the interface. Quantifying these parameters experimentally has remained challenging. Here, we present a theoretical and experimental framework to address this issue, extending our previously developed half-FRAP approach. We solve the spherical diffusion problem with a semipermeable interface by spectral decomposition. By evaluating the information content of the integrated recovery curves, we show that they encode sufficient information to recover interfacial parameters over extended regions of parameter space. Applying our framework to tunable coacervates composed of poly-lysine and hyaluronic acid, we find that their interfaces exhibit strongly biased reflectivity and substantial resistance, both driving preferential internal mixing. These parameters depend on salt concentration, linking interfacial transport to intermolecular interaction strength and position in the phase diagram. Our results establish a quantitative connection between interfacial properties and condensate dynamics, revealing how their interplay gives rise to distinct transport regimes.
title Interfacial Permeability, Reflectivity and Preferential Internal Mixing of Phase-Separated Condensates
topic Biological Physics
Soft Condensed Matter
Subcellular Processes
url https://arxiv.org/abs/2603.25447