Lipid structures exhibit complex and highly dynamic lateral structure; and changes in lipid density and fluidity are believed to play an essential role in membrane targeting and function. The dynamic structure of liquids on the molecular scale can exhibit complex transient density fluctuations. Here the lateral heterogeneity of lipid dynamics is explored in free standing lipid monolayers. As the temperature is lowered the probes exhibit increasingly broad and heterogeneous rotational correlation. This increase in heterogeneity appears to exhibit a critical onset, similar to those observed for glass forming fluids. We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by measuring the rotational diffusion of a fluorescent probe, 1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine (NBD-PC), using wide-field time-resolved fluorescence anisotropy (TRFA). The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ~ 2.4 ns), consistent with previous experimental measures [1, 2]. However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ~ 16.5 ns). This supports the heterogeneity observed for lipids at high packing densities, and demonstrates that the nanoscale diffusion and reorganization in lipid structures can be significantly complex, even in the simplest amorphous architectures. Dynamical heterogeneity of this form can have a significant impact on the organization, permeability and energetics of lipid membrane structures.
Protein driven lipid domain nucleation in biological membranes
脂筏是细胞膜上的异质动态脂质结构域，参与多种生物过程，如蛋白质和脂质特异性转运和信号传导。我们对脂筏形成的理解仍然是有限的，这是由于这些结构域{ \it in vivo}的瞬时和难以捉摸的性质，与在人工膜中观察到的稳定的相分离结构域相反。受实验结果的启发，突出了跨膜蛋白的脂筏的相关性，我们研究了粗粒度的分子动力学和伊辛模型模拟脂质结构域成核。我们发现，跨膜蛋白的存在下，可以触发脂质结构域成核在一个平坦的膜，否则混合脂质相。此外，我们研究的脂质结构域中的蛋白质的扩散的作用表明，其流动性受到阻碍的存在下的筏。因此，我们的粗粒度分子动力学和伊辛模型模拟的结果一致地支持跨膜蛋白在脂质结构域的形成和稳定性中发挥的重要作用。
Computational probes of molecular motion in the Lewis and Whanstrom model for ortho-terphenyl
我们使用分子动力学模拟来研究脆性玻璃形成剂邻三联苯在260 K < T < 346 K和环境压力下的刚性三位模型中的平移和旋转扩散。提出了转动运动的爱因斯坦公式，它补充了常用的德拜模型。后者被证明是打破在过冷温度下的分子重新取向的机制从小的随机步骤大罕见的取向跳跃的变化。我们发现，该模型系统在平移和旋转运动中表现出非高斯行为，这加强了过冷。检查粒子的流动性揭示了空间异质动态的平移和旋转，具有很强的空间相关性之间的摩擦和旋转移动的粒子。应用爱因斯坦形式主义的分析结果在相反的趋势，在传统的方法的基础上的德拜形式主义，即在过冷时的旋转运动相对于平移的有效速率的增强。
M3Scope a 3D multimode multiplane microscope for imaging nanoscale dynamics in soft matter
KU Leuven（荷语鲁汶大学）；Institut Quimic de Sarria, Universitat Ramon Lull（萨拉米亚化学研究所，拉蒙·卢尔大学）；CIC biomaGUNE（CIC生物大分子研究中心）；Centro de Investigación Biomédica en Red, Bioingeniería. Biomateriales y Nanomedicina (CIBER-BBN)（生物、材料工程和纳米医学网络研究中心）；Ghent University（根特大学）；Max Planck Institute for Polymer Research（马克斯·普朗克聚合物研究所）；Ikerbasque, Basque Foundation for Science（伊克尔巴斯基，巴斯克科学基金会）；CINBIO, University of Vigo（CINBIO，维戈大学）
