Condensed Matter Seminar: "Adhering, wrapping, and bursting of fluid membranes: understanding effects of membrane-binding particles and polymers"
Anthony (Tony) Dinsmore, University of Massachusetts, Amherst
Proteins and membranes form remarkably complex structures that are key to intracellular compartmentalization, cargo transport, and cell morphology. Despite this wealth of examples in living systems, we still lack design principles for controlling membrane morphology in synthetic systems. With experiments and simulations, we show that even the simple case of spherical nanoparticles binding to lipid-bilayer membrane vesicles results in a remarkably rich set of morphologies that can be reliably controlled via the particle binding energy. When the binding energy is weak relative to a characteristic membrane-bending energy, vesicles adhere to one another and form a soft solid gel, which is a useful platform for controlled release. With larger binding energy, a transition from partial to complete wrapping of the nanoparticles causes a remarkable vesicle destruction process culminating in rupture, nanoparticle-membrane tubules, and vesicle inversion. These findings help unify the wide range of effects observed when vesicles or cells are exposed to nanoparticles. These results also open the door to a new class of vesicle-based, closed-cell gels that are more than 99% water and can encapsulate and release on demand, and show how to intentionally drive membrane remodeling as a step toward shape-responsive systems.