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 = F(x, y) and adhesion F = F(x, y) forces were measured. Studies of the friction force F on the membrane surface at the nanolevel showed that its value varies discretely with an interval equal to l ≈ 100 nm. It was shown that such discreteness is determined by the interval l of the action of adhesive forces F and indicates the fractal nature of the functional dependence of the friction force on the coordinate F = F(x). Thus, for nano-objects with dimensions ≤ l, the absolute value of F 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.