Interactions between bare or Janus colloidal particles and lipid membranes govern important processes as particle endocytosis, drug delivery and toxicity from nanomaterials. Adhesion and membrane wrapping on the particles are predicted to depend not only on the adhesion strength and the bending of the membrane but also on the spontaneous membrane curvature, which describes the asymmetry between the two leaflets of the lipid bilayer. We are investigating by optical microscopy and optical tweezers the interaction of several bare and Janus colloids (silica, PS, platinum, gold etc ) with GUVs made of different lipids in order to understand and control the engulfment of particles by membranes and vesicles.
By optical tweezers, we were able to measure the force profile during particle wrapping by the membrane and elucidate on the physical requirments to observe the entry of particles in Giant Vesicles.
See the article: Entry of microparticles into giant lipid vesicles by optical tweezers.
We have also studied the adhesion and the wrapping of Janus Colloids by Gaint Vesicle membranes driven by external forces in the absence of strong binding. By obtaining partial wrapping, we have studied the dynamics of self-propelled Janus particles.
See the article: Driven Engulfment of Janus Particles by Giant Vesicles in and out of Thermal Equilibrium.
Nano-objects have a peculiar affinity for cell membranes, and sometimes are able to translocate through it. Their small dimensions, which, in many cases, are of the order of the membrane barrier thickness, but also other factors such as the hydrophobic-hydrophilic balance, are expected to control the interactions. We pursue efforts to understand the fundamental mechanisms of membrane nanoparticle interactions along three routes: i) we develop fast new methods for optical and cryo-TEM (with the EM platform) ii) we finely tune the composition of the lipid membranes, by adding charges, cholesterol or negative curvature lipids, thus approaching compositions of relevant living systems or formulations and iii) we screen different nano-objects (silica, polystyrene, silver, gold and other nanoparticles, cell penetrating peptides with different cargos, cyclodextrins …) in order to explore the relevant parameter space.
See the article: Tear of lipid membranes by nanoparticles.