Chapter 9 Cell Membrane Mechanics

This chapter discusses the cell membrane mechanics. Biological membranes are critical to the life of a cell because the hydrophobic interior of the phospholipid bilayer forms a barrier to the transport of solutes and macromolecules between the cell interior and its environment. In many respects biological membranes can be treated as two-dimensional materials. Strictly speaking, they are continuous only in the two dimensions of the cell surface, with a molecular character in the direction normal to the surface. The important mechanical properties of the membrane include its elastic modulus, shear modulus, bending stiffness, and viscosity. From the view of mechanics, membranes have a remarkably low shear modulus, a high elastic modulus, and a reasonable bending stiffness influenced strongly by the membrane proteins, including cytoskeletal elements. Another mechanical feature of bilayers is that the two surfaces can be independently modulated, which will induce curvature through the bilayer couple.