Transport Dynamics of Nanoconfined Water within Lipid Membranes
ABSTRACT
Understanding of water behavior confined between biological membranes in nanoscale is crucial to elucidate various biological functions. The interfacial environment between the membrane and water plays a significant role in governing the dynamic properties of nanoconfined water. Despite extensive investigations into the dynamic properties of nanoconfined water, a quantitative understanding of the dynamic heterogeneity of water motion and its relationship with the interfacial environment remains elusive. In this study, we present a novel transport equation for water molecules in the intermembrane space [1], providing a quantitative explanation for molecular dynamics (MD) simulation results. Our findings reveal that the unique transport dynamics of water molecules arises from fluctuations in the lateral diffusion coefficient, influenced by their longitudinal motion perpendicular to the membranes. Furthermore, we extend this framework to examine how the addition of divalent cations influences the dynamics of water molecules, revealing that the ions act as bridges between water and lipid headgroups rather than as electrostatic screens [2].
[1] M. Lee, E. Lee, J.-H. Kim, H. Hwang, M. Cho, and J. Sung, Transport Dynamics of Water Molecules Confined between Lipid Membranes, J. Phys. Chem. Lett. 15, 4437 (2024).
[2] M. Lee, J. Park, J.-H. Kim, M. Cho, and J. Sung, Effects of divalent cations on diffusion dynamics of biological water confined between lipid membranes, J. Chem. Phys. 164, (2026).
