Biolubrication From Phospholipid Membranes: A Correlation between Nanomechanical Stability and Tribological Properties

The role of phospholipid bilayers, buffer and ions in controlling and reducing frictional forces between biological surfaces is investigated by tribological and AFM methods. DPPC lipid bilayers in the solid phase generate friction coefficients as low as 0.002 (comparable to that found for cartilage) stable through time. DOPC bilayers generate higher friction coefficients and are more easily punctured by the AFM tip in water but not in buffers. These results demonstrate that the slip plane during shear is located in the thin aqueous layer between bilayers and strongly suggest that ions trapped in this layer are important in lubrication.