Enforced unbinding of biomembranes whose mutual adhesion is mediated by a specific interaction

The enforced unbinding of a biomembrane from a rigid substrate whose adhesion is mediated by a specific interaction has been studied theoretically. We argue that the unbinding takes place via motion of the adhesion rim. We account for the release of the elastic energy (stored in the membrane curvature) in the binding-unbinding process and obtain the dissociation constant at the rim. We further deduce an equation of motion for the rim. The solution exhibits an initial phase describing a slow motion followed by a regime of rapid motion and finally breaking of the adhesion. We show that the unbinding force depends on the rate of force application as F(*) approximately equal (F')(beta). When small forces are applied, beta=1/2, while in the case of large forces, beta=1/3.