Nanomechanical Properties of Supported Lipid Bilayers studied by Force Spectroscopy

摘要

The physicochemical properties of biological membranes are crucial to understand membrane function, since their main role is to provide a barrier that divides electrolytic solutions into different compartments guaranteeing at the same time membrane mechanical stability. It is well-known that the chemical composition of the phospholipid molecules that compose the membrane greatly determine the architecture of such biological systems. Force Spectroscopy with AFM is a powerful tool able to study the nanomechanical properties of supported planar bilayers (SPBs). Force plots on lipid bilayers show a discontinuity in the approaching curve that is interpreted as the penetration of the AFM tip through the lipid bilayer. The force at which this discontinuity occurs is the maximum force the bilayer is able to withstand before breaking and it can be regarded as a "fingerprint" of the bilayer stability, just like force is the fingerprint for a protein to unfold or for a hard material surface to be indented. We report on an experimental quantitative Force Spectroscopy study on how both lipid bilayer stability and compactness depend on the solution ionic composition.