title: Local membrane mechanics of pore-spanning bilayers.
abstract: The mechanical behavior of lipid bilayers spanning the pores of highly ordered porous silicon substrates was scrutinized by local indentation experiments as a function of surface functionalization, lipid composition, solvent content, indentation velocity, and pore radius. Solvent-containing nano black lipid membranes (nano-BLMs) as well as solvent-free pore-spanning bilayers were imaged by fluorescence and atomic force microscopy prior to force curve acquisition, which allows distinguishing between membrane-covered and uncovered pores. Force indentation curves on pore-spanning bilayers attached to functionalized hydrophobic porous silicon substrates reveal a predominately linear response that is mainly attributed to prestress in the membranes. This is in agreement with the observation that indentation leads to membrane lysis well below 5% area dilatation. However, membrane bending and lateral tension dominate over prestress and stretching if solvent-free supported membranes obtained from spreading giant liposomes on hydrophilic porous silicon are indented. An elastic regime diagram is presented that readily allows determining the dominant contribution to the mechanical response upon indentation as a function of load and pore radius.
authors.affiliation: Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Mey
authors.forename: Milena
authors.initials: M
authors.lastname: Stephan
authors.forename: Eva K
authors.initials: EK
authors.lastname: Schmitt
authors.forename: Martin Michael
authors.initials: MM
authors.lastname: Müller
authors.forename: Martine
authors.initials: M
authors.lastname: Ben Amar
authors.forename: Claudia
authors.initials: C
authors.lastname: Steinem
authors.forename: Andreas
authors.initials: A
authors.lastname: Janshoff
mesh_terms: D006046:Gold / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D008956:Models, Chemical; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013314:Stress, Mechanical
chemical_list: D008051:Lipid Bilayers; D010767:Phosphorylcholine; D006046:Gold; D012825:Silicon