Cell-Sized Confinements Alter Molecular Diffusion in Concentrated Polymer Solutions Due to Length-Dependent Wetting of Polymers

• Published in: ACS Materials Au 2023-09, Vol.3 (5), p.442-449
• Main Authors: Kanakubo, Yuki, Watanabe, Chiho, Yamamoto, Johtaro, Yanagisawa, Naoya, Sakuta, Hiroki, Nikoubashman, Arash, Yanagisawa, Miho
• Format: Article
• Language: English
• Subjects: Letter
• ISSN: 2694-2461; 2694-2461
• DOI: 10.1021/acsmaterialsau.3c00018

Living cells are characterized by the micrometric confinement of various macromolecules at high concentrations. Using droplets containing binary polymer blends as artificial cells, we previously showed that cell-sized confinement causes phase separation of the binary polymer solutions because of the length-dependent wetting of the polymers. Here, we demonstrate that the confinement-induced heterogeneity of polymers also emerges in single-component polymer solutions. The resulting structural heterogeneity also leads to a slower transport of small molecules at the center of cell-sized droplets than that in bulk solutions. Coarse-grained molecular simulations support this confinement-induced heterogeneous distribution by polymer length and demonstrate that the effective wetting of the shorter chains at the droplet surface originates from the length-dependent conformational entropy. Our results suggest that cell-sized confinement functions as a structural regulator for polydisperse polymer solutions that specifically manipulates the diffusion of molecules, particularly those with sizes close to the correlation length of the polymer chains.