title: Ultrathin spin-coated dioleoylphosphatidylcholine lipid layers in dry conditions: a combined atomic force microscopy and nanomechanical study.
abstract: Atomic force microscopy (AFM) has been used to study the structural and mechanical properties of low concentrated spin-coated dioleoylphosphatidylcholine (DOPC) layers in dry environment (RH ≈ 0%) at the nanoscale. It is shown that for concentrations in the 0.1-1 mM range the structure of the DOPC spin-coated samples consists of an homogeneous lipid monolayer ∼1.3 nm thick covering the whole substrate on top of which lipid bilayer (or multilayer) micro- and nanometric patches and rims are formed. The thickness of the bilayer structures is found to be ∼4.5 nm (or multiples of this value for multilayer structures), while the lateral dimensions range from micrometers to tens of nanometer depending on the lipid concentration. The force required to break a bilayer (breakthrough force) is found to be ∼0.24 nN. No dependence of the mechanical values on the lateral dimensions of the bilayer structures is evidenced. Remarkably, the thickness and breakthrough force values of the bilayers measured in dry environment are very similar to values reported in the literature for supported DOPC bilayers in pure water.
authors.affiliation: Nanobioelec group, Institut de Bioenginyeria de Catalunya (IBEC), Baldiri i Reixac 15-21, 08028 Barcelona, Spain. adols@ibec.pcb.ub.es
authors.forename: Aurora
authors.initials: A
authors.lastname: Dols-Perez
authors.forename: Laura
authors.initials: L
authors.lastname: Fumagalli
authors.forename: Adam Cohen
authors.initials: AC
authors.lastname: Simonsen
authors.forename: Gabriel
authors.initials: G
authors.lastname: Gomila
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D010713:Phosphatidylcholines / Q000737:chemistry*; D012996:Solutions
chemical_list: D000538:Aluminum Silicates; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D012996:Solutions; C017251:1,2-oleoylphosphatidylcholine; C011934:mica