Department of Chemistry, Indian Institute of Technology Patna, Bihar 801106, India.
J Phys Chem B. 2023 Jun 8;127(22):4939-4951. doi: 10.1021/acs.jpcb.3c00019. Epub 2023 May 25.
Past experiments rationalized the observed dynamic heterogeneity and non-Gaussian diffusion in living cell membranes in terms of slow-active remodeling of the underlying cortical actin network. In this work, we demonstrate that the nanoscopic dynamic heterogeneity can also be explained via the lipid raft hypothesis, which postulates a phase separation between liquid-ordered (Lo) and liquid-disordered (Ld) nanodomains. Non-Gaussian displacement distribution is observed in the Lo domain for a long time, even when the mean square displacement becomes Fickian. This Fickian yet non-Gaussian diffusion is found particularly in the Lo/Ld interface consistent with the "diffusing diffusion" picture. A translational jump-diffusion model, previously employed to explain the diffusion-viscosity decoupling in supercooled water, is used here to quantitatively explain the long-term dynamic heterogeneity where a strong correlation between translational jump and non-Gaussian diffusion is observed. Therefore, this study proposes a novel approach to elucidate the dynamic heterogeneity and non-Gaussian diffusion in the cell membrane crucial for various cell membrane functionalities.
过去的实验从底层皮质肌动蛋白网络的缓慢主动重塑的角度出发，对活细胞膜中观察到的动态异质性和非高斯扩散进行了合理化解释。在这项工作中，我们证明纳米级动态异质性也可以通过脂质筏假说来解释，该假说假定在有序液体 (Lo) 和无序液体 (Ld) 纳米域之间存在相分离。即使均方位移呈菲克扩散，Lo 域中的非高斯位移分布也会持续很长时间。这种菲克扩散而非高斯扩散在 Lo/Ld 界面处特别明显，与“扩散扩散”图像一致。先前用于解释过冷水中扩散-粘性解耦的平移跳跃扩散模型，此处用于定量解释长期动态异质性，其中观察到平移跳跃和非高斯扩散之间存在强相关性。因此，这项研究提出了一种新方法来阐明细胞膜中的动态异质性和非高斯扩散，这对各种细胞膜功能至关重要。
