Dynamic strengths of molecular anchoring and material cohesion in fluid biomembranes

Building on Kramers' theory for reaction kinetics in liquids and using laboratory experiments, we show how strengths of molecular anchoring and material cohesion in fluid-lipid membranes increase with rate of force and tension loading. Expressed on a scale of log(loading rate), the dynamic spectra of pull-out forces and rupture tensions image the microscopic and mesoscopic energy barriers traversed in molecular extraction and membrane failure. To capture such images, we have pulled single molecules from membranes with force rates from 1 to 10 4 pN s -1 and ruptured giant membrane vesicles with tension rates from 10 -2 to 10 2 mN m -1 s -1 .