title: Structure and Nanomechanics of Model Membranes by Atomic Force Microscopy and Spectroscopy: Insights into the Role of Cholesterol and Sphingolipids.
abstract: Biological membranes mediate several biological processes that are directly associated with their physical properties but sometimes difficult to evaluate. Supported lipid bilayers (SLBs) are model systems widely used to characterize the structure of biological membranes. Cholesterol (Chol) plays an essential role in the modulation of membrane physical properties. It directly influences the order and mechanical stability of the lipid bilayers, and it is known to laterally segregate in rafts in the outer leaflet of the membrane together with sphingolipids (SLs). Atomic force microscope (AFM) is a powerful tool as it is capable to sense and apply forces with high accuracy, with distance and force resolution at the nanoscale, and in a controlled environment. AFM-based force spectroscopy (AFM-FS) has become a crucial technique to study the nanomechanical stability of SLBs by controlling the liquid media and the temperature variations. In this contribution, we review recent AFM and AFM-FS studies on the effect of Chol on the morphology and mechanical properties of model SLBs, including complex bilayers containing SLs. We also introduce a promising combination of AFM and X-ray (XR) techniques that allows for in situ characterization of dynamic processes, providing structural, morphological, and nanomechanical information.
authors.affiliation: Nanoprobes and Nanoswitches group, Institute for Bioengineering of Catalunya (IBEC), Barcelona 08028, Spain. bgumi@ibecbarcelona.eu.|Physical Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain. bgumi@ibecbarcelona.eu.|European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France. bgumi@ibecbarcelona.eu.|Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28028, Spain. bgumi@ibecbarcelona.eu.
authors.forename: Berta
authors.initials: B
authors.lastname: Gumí-Audenis
authors.affiliation: Structure and Dynamics of Nucleoproteic and Membrane Assemblies, Centre de Biochimie Structurale (CBS), Montpellier 34090, France. costa@cbs.cnrs.fr.
authors.forename: Luca
authors.initials: L
authors.lastname: Costa
authors.affiliation: European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France. francesco.carla@esrf.fr.
authors.forename: Francesco
authors.initials: F
authors.lastname: Carlá
authors.affiliation: European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France. comin@esrf.fr.
authors.forename: Fabio
authors.initials: F
authors.lastname: Comin
authors.affiliation: Nanoprobes and Nanoswitches group, Institute for Bioengineering of Catalunya (IBEC), Barcelona 08028, Spain. fsanz@ub.edu.|Physical Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain. fsanz@ub.edu.|Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28028, Spain. fsanz@ub.edu.
authors.forename: Fausto
authors.initials: F
authors.lastname: Sanz
authors.affiliation: Nanoprobes and Nanoswitches group, Institute for Bioengineering of Catalunya (IBEC), Barcelona 08028, Spain. migiannotti@ub.edu.|Physical Chemistry Department, Universitat de Barcelona, Barcelona 08028, Spain. migiannotti@ub.edu.|Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28028, Spain. migiannotti@ub.edu.
authors.forename: Marina I
authors.initials: MI
authors.lastname: Giannotti
keywords: XR-AFM combination; atomic force microscopy; cholesterol; force spectroscopy; lipid membranes; membrane structure; nanomechanics; sphingolipids; supported lipid bilayers