Lipid bilayer mechanics

Lipid bilayer mechanics is the study of the physical material properties of lipid bilayers, classifying bilayer behavior with stress and strain rather than biochemical interactions. Local point deformations such as membrane protein interactions are typically modelled with the complex theory of biological liquid crystals but the mechanical properties of a homogeneous bilayer are often characterized in terms of only three mechanical elastic moduli: the area expansion modulus K_a, a bending modulus K_b and an edge energy ${\displaystyle \Lambda }$. For fluid bilayers the shear modulus is by definition zero, as the free rearrangement of molecules within plane means that the structure will not support shear stresses. These mechanical properties affect several membrane-mediated biological processes. In particular, the values of K_a and K_b affect the ability of proteins and small molecules to insert into the bilayer.^[1][2] Bilayer mechanical properties have also been shown to alter the function of mechanically activated ion channels.^[3]