Abstract
Flexible membranes which are in contact with dispersed nanoparticles or colloids are theoretically studied. For closed vesicles, the membrane/particle interactions change the "spontaneous" curvature of the membrane provided the surrounding solution contains more than one species of particles. If the membrane/particle interactions are repulsive, the membrane curves toward the larger particles. If the membrane/particle interactions are attractive, the membrane curves away from the adsorption layers of small particles but wraps itself around large particles which become completely encapsulated.