The adsorption of particles to a membrane can have profound effects, both upon the membrane and upon the dynamics of the particles. We found that the addition of cationic nanoparticles stabilizes zwitterionic liposome headgroups, allowing the creation of dense suspensions of lipid vesicles. For larger vesicles, the addition of nanoparticles may also significantly perturb the morphology of the vesicles. At the same time, coupling with membrane fluctuations can cause significant deviations from normal Brownian motion for adsorbed particles, as we found for particles adsorbed on a lipid tubule.

Janus particles are (micron-sized) colloidal particles which have been modified to present two different faces. For the majority of our research, hemispherical metal coatings are applied, such that when imaged with a microscope, the particles look like little moons, whether full, half, or crescent. I have developed techniques which allow us to determine the position of these colloids in four dimensions (two translational, two rotational). Besides allowing such imaging, the coated side can also be independently chemically modified, which we have exploited in studying amphiphilic colloidal interactions. Research directions include the coupling of translational and rotational motion, both for clusters of particles and hydrodynamic coupling between nearby particles, colloidal self-assembly, and the interactions of amphiphilic particles.