MSC Seminar. 13/03/2025. 11h00. Chiho Watanabe (Hiroshima University, Japan): “Cell size space effect on crowded polymer solutions”

Cells confine macromolecularly crowded solutions of biopolymers (proteins, nucleic acids, polysaccharides, etc.) inside lipid-based membranes. Typical cell sizes range from a few to tens of microns, with corresponding volumes of fL to pL. In such a cell-size space, the confined solution may behave differently than the unconfined bulk solution over µL volumes. Here, we used water-in-oil emulsion polymer droplets to model the cell structure and investigated how cell-size space confinement with lipid membranes affects the physicochemical properties of the internal polymer solutions. We found that, above a certain concentration, molecular diffusion slows down with decreasing confinement size. In addition, cell-size space confinement induces phase separation, with the composition exhibiting a homogeneous phase in a bulk solution. These results suggest that cell size confinement with lipid membranes can influence the behavior of macromolecularly crowded solutions. [1–4]

[1] C. Watanabe, Y. Kobori, J. Yamamoto, M. Kinjo, and M. Yanagisawa, Quantitative Analysis of Membrane Surface and Small Confinement Effects on Molecular Diffusion, J. Phys. Chem. B 124, 1090 (2020).

[2] K. Harusawa, C. Watanabe, Y. Kobori, K. Tomita, A. Kitamura, M. Kinjo, and M. Yanagisawa, Membrane Surface Modulates Slow Diffusion in Small Crowded Droplets, Langmuir 37, 437 (2021).

[3] C. Watanabe, T. Furuki, Y. Kanakubo, F. Kanie, K. Koyanagi, J. Takeshita, and M. Yanagisawa, Cell-Sized Confinement Initiates Phase Separation of Polymer Blends and Promotes Fractionation upon Competitive Membrane Wetting, ACS Materials Lett. 4, 1742 (2022).

[4] Y. Kanakubo, C. Watanabe, J. Yamamoto, N. Yanagisawa, H. Sakuta, A. Nikoubashman, and M. Yanagisawa, Cell-Sized Confinements Alter Molecular Diffusion in Concentrated Polymer Solutions Due to Length-Dependent Wetting of Polymers, ACS Mater. Au 3, 442 (2023).