AVS 51st International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuA

Paper NS-TuA6
Friction Measurements of DMPC Phospholipidic Bilayers

Tuesday, November 16, 2004, 3:00 pm, Room 213D

Session: Nanostructures and Biology
Presenter: G. Oncins, Universitat de Barcelona, Spain
Authors: G. Oncins, Universitat de Barcelona, Spain
S. Garcia-Manyes, Universitat de Barcelona, Spain
F. Sanz, Universitat de Barcelona, Spain
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Self-assembled phospholipid layers have been a matter of extensive research during last decades. The high content of these structures in cellular membranes has led to their use as models for the study of a wide bunch of biological, biochemical, biophysical and medical issues. Besides, the Supported Planar Bilayers (SPBs) have been very useful in the study of interaction and adhesion forces between cells, in the modelling of the diffusion kinetics of phospholipids and in the insertion of proteins in membranes. AFM has proved to be the most suitable technique to obtain molecular topographic resolution of these systems and to study the morphology of SPBs under various conditions. We have recently worked with such structures at a nanometric level, mostly performing studies based on AFM force spectroscopy measurements of 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers@footnote 1@. The present work has used Lateral Force Microscopy (LFM) to mechanically test DMPC bilayers supported on mica, performing a series of experiments with laterally and vertically calibrated tips in aqueous environment and in which NaCl concentration has been ramped from 0M to 0.1M. Obtained friction results have been complemented with AFM height images of the same tested bilayer area, being able to relate each friction signal with its corresponding topography. Results have shown that the presence of NaCl modifies drastically the mechanical response of the DMPC bilayer, and, consequently, of the cellular phospholipidic membrane. @FootnoteText@ @footnote 1@Garcia-Manyes, S. ;Oncins, G.; Sanz, F.; Effect of ionic solutions on the nanomechanics of a model lipid bilayer: a quantitative Force Spectroscopy contribution, submitted to JACS Communications.).