title: Pore-spanning lipid membrane under indentation by a probe tip: a molecular dynamics simulation study.
abstract: We study the indentation of a free-standing lipid membrane suspended over a nanopore on a hydrophobic substrate by means of molecular dynamics simulations. We find that in the course of indentation the membrane bends at the point of contact and the fringes of the membrane glide downward intermittently along the pore edges and stop gliding when the fringes reach the edge bottoms. The bending continues afterward, and the large strain eventually induces a phase transition in the membrane, transformed from a bilayered structure to an interdigitated structure. The membrane is finally ruptured when the indentation goes deep enough. Several local physical quantities in the pore regions are calculated, which include the tilt angle of lipid molecules, the nematic order, the included angle, and the distance between neighboring lipids. The variations of these quantities reveal many detailed, not-yet-specified local structural transitions of lipid molecules under indentation. The force-indentation curve is also studied and discussed. The results make a connection between the microscopic structure and the macroscopic properties and provide deep insight into the understanding of the stability of a lipid membrane spanning over nanopore.
authors.affiliation: Department of Engineering and System Science, National Tsing Hua University, Taiwan, Republic of China.
authors.forename: Chen-Hsi
authors.initials: CH
authors.lastname: Huang
authors.forename: Pai-Yi
authors.initials: PY
authors.lastname: Hsiao
authors.forename: Fan-Gang
authors.initials: FG
authors.lastname: Tseng
authors.forename: Shih-Kang
authors.initials: SK
authors.lastname: Fan
authors.forename: Chien-Chung
authors.initials: CC
authors.lastname: Fu
authors.forename: Rong-Long
authors.initials: RL
authors.lastname: Pan
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D008567:Membranes, Artificial; D056004:Molecular Dynamics Simulation; D058608:Nanopores
chemical_list: D008567:Membranes, Artificial