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Updated: May 30, 2026
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Published on: October 24, 2017
Phase behavior of crowded like-charged mixed polyelectrolytes in a cell-sized sphere
Makiko Negishi1, Masatoshi Ichikawa, Masahiro Nakajima
1Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan.
Summary
Giant DNA and alginate mixtures show unique phase behavior within cell-sized spheres. Sphere size dictates polymer distribution, unlike homogeneous bulk solutions, due to surface-to-volume effects.
Area of Science:
- Polymer Physics
- Biophysics
- Materials Science
Background:
- Semiflexible polyelectrolytes like giant DNA and alginate are crucial in biological systems.
- Understanding polymer behavior in confined environments is essential for cell biology and nanotechnology.
- Crowded conditions and confinement significantly alter polymer phase behavior compared to bulk solutions.
Purpose of the Study:
- To investigate the phase behavior of a mixture of giant DNA and alginate under crowded conditions within cell-sized spheres.
- To determine how sphere size influences the spatial distribution and phase separation of these polyelectrolytes.
- To elucidate the role of surface-to-volume effects in confined polymer systems.
Main Methods:
- Microscopic observation of polymer mixtures in spheres ranging from 5-40 μm in diameter.
- Utilizing the Flory-Huggins model with a novel curvature-dependent interaction term.
- Comparing phase behavior in confined spheres to that of bulk solutions.
Main Results:
- The polymer mixture exhibited homogeneous and isotropic behavior in bulk solution.
- In small spheres, giant DNA was completely depleted from the surface.
- In medium-sized spheres, partial depletion of giant DNA from the surface was observed, with the remainder staying within the sphere.
Conclusions:
- The phase behavior of giant DNA and alginate mixtures is strongly dependent on the size of the confining sphere.
- Surface-to-volume effects, particularly the curvature-dependent interaction, govern the observed phase separation.
- This study provides insights into polymer behavior in cellular microenvironments and confined geometries.
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