Abstract
Using molecular dynamics simulations, we investigate the mechanical properties of lipid membranes spanning over funnel-like nanopores under the action of an indenting probe. Two linear regimes are identified in the force-indentation curves with the apparent spring constant in the first regime about twice of the one in the second. The occurrence of the second regime is attributed to a local phase transition of membrane from bilayered structure to interdigitated one. At large indentation, rupture of membrane happens. The rupture point depends on the pore geometry, locating at opposite sides of pore for the convergent and divergent pore systems, owing to the tilting of lipid molecules. We study the amount of lipid molecules dragged into the pore region, the maximum depression depth, the maximum bending angle, and the membrane lifetime under indentation. The results show important influences of pore geometry. The convergent-pore membranes are more sustained than the divergent-pore ones.