Dynamic Excitations in Membranes Induced by Optical Tweezers

We present the phenomenology of transformations in lipid bilayers that are excited using laser tweezers. A variety of dynamic instabilities and shape transformations are observed, including the pearling instability, expulsion of vesicles and more exotic ones such as the formation of passages. Our physical picture of the laser–membrane interaction is based on the generation of tension in the bilayer and loss of surface area. While tension is the origin of the pearling instability, it does not suffice to explain expulsion of vesicles, where we observe the opening of giant pores and creeping motion of bilayers. We present a quantitative theoretical framework to understand most of the observed phenomenology. The main hypothesis that lipid gets pulled into the optical trap by the familiar dielectric effect, is disrupted, and finally gets repackaged into an optically unresolvable suspension of colloidal particles. This suspension can in turn produce osmotic pressure and depletion forces, driving the observed transformations.