Curvature-Induced Lateral Organization in Mixed Lipid Bilayers Supported on a Corrugated Substrate

Structure Evolution of Binary Ligands on Nanoparticles Triggered by Competition between Adsorption Reaction and Phase Separation

The ligand shell of a nanoparticle (NP) determines most of the interfacial properties through its composition and structure. Despite widespread study over the years, the factors impacting the ligand shell structures, especially the effects of ligand-adsorption kinetics in solution, are still not clear and even conflict with each other. We have developed an adsorption-migration reaction model to study the dynamic evolution processes of binary ligands on NP surfaces during adsorption reaction. Apparent dependence of the structure of ligand shells on ligand-adsorption and phase-separation rates has been found, which induces the formation of different shell patterns, including Janus, patchy, stripe, and island patterns. The formation process of these patterns accords with different reaction kinetic pathways, depending on the nature of ligands. Further screening the role of the NPs' curvature reveals that it can indirectly influence the ligand-adsorption and phase-separation kinetics. As the NPs' curvature increases, an accelerated ligand-adsorption and phase-separation process on NPs will happen, resulting in the preferential formation of more ordered Janus or stripe patterns. These results suggest that controlling the reaction kinetics is key to effectively regulating the composition and morphology of binary ligands on NPs. They also provide principles for guiding the experimental studies to fabricate novel NPs with a functional surface for use in broad nanoscience fields.

Buckling Under Pressure: Curvature-Based Lipid Segregation and Stability Modulation in Cardiolipin-Containing Bilayers

Mitochondrial metabolic function is affected by the morphology and protein organization of the mitochondrial inner membrane. Cardiolipin (CL) is a unique tetra-acyl lipid that is involved in the maintenance of the highly curved shape of the mitochondrial inner membrane as well as spatial organization of the proteins necessary for respiration and oxidative phosphorylation. Cardiolipin has been suggested to self-organize into lipid domains due to its inverted conical molecular geometry, though the driving forces for this organization are not fully understood. In this work, we use coarse-grained molecular dynamics simulations to study the mechanical properties and lipid dynamics in heterogeneous bilayers both with and without CL, as a function of membrane curvature. We find that incorporation of CL increases bilayer deformability and that CL becomes highly enriched in regions of high negative curvature. We further show that another mitochondrial inverted conical lipid, phosphatidylethanolamine (PE), does not partition or increase the deformability of the membrane in a significant manner. Therefore, CL appears to possess some unique characteristics that cannot be inferred simply from molecular geometry considerations.

Curvature-based interaction potential between a micro/nano curved surface body and a particle on the surface of the body

The interaction potential between a curved surface body and a particle located on the surface of the body is studied in this paper. Based on the negative exponential pair potential (1/R(n)) between particles, the interaction potential is proved to be of the curvature-based form, i.e., it can be written as a function of curvatures of the surface. Idealized numerical experiments are designed to test the accuracy of curvature-based potential. Based on the curvature-based potential, propositions below are confirmed: a highly curved surface body will induce driving forces on the particle located on the surface, and curvatures and the gradients of curvatures are essential factors forming the driving forces. In addition, the tangent driving force acting on the particle from the curved surface body is studied. Based on duality, the following rule is proved: for a convex or concave curved body sharing the same curved surface, the curvature-based interaction potential between them and a particle on the surface can make up the potential of a particle in the whole space.

Interplay between curvature and lateral organization of lipids and peptides/proteins in model membranes

Membrane curvature plays a crucial role in the realization of many cellular membrane functions such as signaling and trafficking. Here, using coarse-grained molecular dynamics (MD) simulation, we present an effective method of producing curved model membranes and systematically investigated the interplay between the curvature and lateral sorting of lipids and transmembrane (TM) peptides/proteins in the model membranes. We first confirmed the experimental results of the lateral organization of lipid domains in curved ternary membranes. Then, we focused on exploring the lateral sorting of TM peptides/proteins with symmetric shape in the curved membranes. The results showed that the lateral inhomogeneous packing of lipids induced by the curvature and/or the component heterogeneity drives the peptides/proteins to accumulate in the curved regions in both the unary and ternary membranes. However, whether the peptides/proteins can stably and compactly reside in the curved regions is determined by their final packing configuration, which may be influenced by the membrane curvature in the curved regions. Additionally, the insertion of peptides/proteins may enhance the membrane curvature. This work provided some theoretical insights into understanding the mechanism of the interplay of membrane curvature and lateral organization (especially the lateral sorting of the peptides/proteins with symmetric shape) in the biomembrane in some biological processes.