The puzzle of sphingolipids and cholesterol under the atomic force microscope: bilayer thicknesses and breakthrough...

A variety of studies published in the last decades in the field of lipid biophysics deal with the puzzle regarding the relationship between the signaling power of bioactive lipids (sphingolipids) and their capacity to induce lipid membrane heterogeneity (domains). Advances in technology, particularly Atomic Force Microscopy (AFM), have provided a solid contribution in this regard. Moreover, supported planar bilayers (SPB) have become an established membrane model in the study of lipid-lipid interactions. However, in spite of the large amount of published results in this field, the data remain scattered, and a coherent collection that allows easy access to the investigator is missing. This review summarizes the relevant results obtained in our laboratory through the use of AFM under comparable experimental conditions, offering a collection of data on supported lipid bilayer thicknesses and breakthrough forces. An extensive list of lipid compositions including phospholipids, cholesterol and sphingolipids (sphingomyelins, ceramides), at varying molecular ratios, has been considered.