Study of tribological properties of human buccal epithelium cell membranes using probe microscopy

In this work demostrates a unique method for determining the absolute value of the friction force of a nanoobject on the surface of a cell membrane using atomic force microscopy. The tribological properties of membranes of adult human buccal epithelium cells in the presence of a protective adsorption buffer layer of ~ 100 nm on their surface were studied using atomic force microscopy in the contact scanning mode. Local mapping of the tribological characteristics of the surface was carried out, viz. friction F(L) = F(L)(x, y) and adhesion F(adh) = F(adh)(x, y) forces were measured. Studies of the friction force F(fr) on the membrane surface at the nanolevel showed that its value varies discretely with an interval equal to l(LF) ≈ 100 nm. It was shown that such discreteness is determined by the interval l(LF) of the action of adhesive forces F(adh) and indicates the fractal nature of the functional dependence of the friction force on the coordinate F(fr) = F(fr)(x). Thus, for nano-objects with dimensions ≤ l(LF), the absolute value of F(fr) decreases according to a power law with an increase in the size of the object, which contradicts the similar dependence of the friction force for macro-objects in the global approximation.