Exploring the Properties and Interactions of Supported Lipid Bilayers on the Nanoscale by Atomic Force Microscopy

Supported lipid bilayers (SLBs) are biomimetic model systems that are now widely used to address the biophysical and biochemical properties of biological membranes. Two main methods are usually employed to form SLBs: the transfer of two successive monolayers by Langmuir-Blodgett or Langmuir-Schaefer techniques, and the fusion of preformed lipid vesicles. The transfer of lipid films on flat solid substrates offers the possibility to apply a wide range of surface analytical techniques that are very sensitive. Among them, atomic force microscopy (AFM) has opened new opportunities for determining the nanoscale organization of SLBs under physiological conditions. In this review, we will first focus on the different protocols generally employed to prepare SLBs. Then, we will describe AFM studies on the nanoscale lateral organization and mechanical properties of SLBs. In the last part of this review, we will survey the recent developments in the AFM monitoring of bilayer alteration, remodelling or digestion, by the incubation with external agents such as drugs, detergents, proteins, peptides, nanoparticles, and solvents.