Size-controlled clusters: Clusters of preformed 15 nm oleic acid coated superparamagnetic iron oxide nanoparticles were prepared through partially destabilizing suspensions of the dispersed nanoparticles with CN-modified silica. This effect induced gradual formation of monodisperse, superparamagnetic clusters by competition between the solid phases for the surfactant. The cluster size can be controlled within the range 15–200 nm as the growth process can be stopped and restarted.
