Line Tension of Pore Edge in Membrane on Solid Support

Controlled formation of through pores in bilayer lipid membranes is a key stage of various biotechnological techniques. Excess energy of the pore edge is characterized by line tension, the value of which determines the overall stability of the membrane with respect to pore formation. The practically important pore size is on the order of a few nanometers. It is impossible to study such pores by direct optical methods, but they can, in principle, be visualized by atomic force microscopy. This method uses a solid support on which the lipid bilayer is held due to the interaction of one of the monolayers with it. In this work, we theoretically investigated the effect of the presence of the support on the value of the line tension of the pore edge. It was assumed that the line tension is determined by the energy of elastic deformation of the membrane at the edge. Various regimes of membrane interaction with the support were considered: from a free-standing membrane (complete absence of interaction) to the case of infinitely strong adhesion of the membrane to the support. The calculation results show that the relative change in the line tension of the pore edge within such variation of the intensity of the interaction of the membrane with the support is less than 3.5%. Thus, the developed theoretical model predicts an extremely weak effect of the interaction with the support on the magnitude of the line tension–the main energy characteristic of the pore edge.