Biomimetic Curvature and Tension-Driven Membrane Fusion Induced by Silica Nanoparticles

Abstract

Membrane fusion is a key process to develop new technologies in synthetic biology, where artificial cells function as biomimetic chemical microreactors. Fusion events in living cells are intricate phenomena that require the coordinate action of multicomponent protein complexes. However, simpler synthetic tools to control membrane fusion in artificial cells are highly desirable. Native membrane fusion machinery mediates fusion driving a delicate balance of membrane curvature and tension between two closely apposed membranes. Here we show that silica nanoparticles (SiO<sub>2</sub> NPs) at a size close to the cross-over between tension-driven and curvature-driven interaction regimes initiate efficient fusion of biomimetic model membranes. Fusion efficiency and mechanisms are studied by Förster Resonance Energy Transfer (FRET) and confocal fluorescence microscopy. SiO<sub>2</sub> NPs induce a slight increase in lipid packing likely to increase the lateral tension of the membrane. We observe a connection between membrane tension and fusion efficiency. Finally, real-time confocal fluorescence microscopy reveals three distinct mechanistic pathways for membrane fusion. SiO<sub>2</sub> NPs show significant potential for inclusion in the synthetic biology toolkit for membrane remodelling and fusion in artificial cells.