Pressure-driven membrane inflation through nanopores on the cell wall

Abstract

Walled cells, such as in plants and fungi, compose an important part of the model systems in biology. The cell wall primarily prevents the cell from over-expansion when exposed to water, and is a porous material distributed with nanosized pores on it. In this paper, we study the deformation of a membrane patch by an osmotic pressure through a nanopore on the cell wall. We find that there exists a critical pore size or a critical pressure beyond which the membrane cannot stand against the pressure and would inflate out through the pore and further expand. The critical pore size scales linearly with the membrane tension and quadratically with the spontaneous curvature. The critical pressure is inversely proportional to the pore radius. Our results also show that the fluid membrane expansion by pressure is mechanically different from the solid balloon expansion, and predict that the bending rigidity of the membrane in walled cells should be much larger than that of the mammalian cells so as to prevent membrane inflation through the pores on the cell wall.