A general strategy is described which allows for transferring hydrophobically capped nanocrystals from organic to aqueous solution by wrapping an amphiphilic polymer around the particles. In particular, high quality CoPt 3 , Au, CdSe/ZnS, and Fe 2 O 3 nanocrystals have been water-solubilized in this way. Analysis with transmission electron microscopy, gel electrophoresis, and fluorescence correlation spectroscopy demonstrates that monodispersity of the particles is conserved upon phase transfer to aqueous solution.

Silver nanoparticles coated with a uniform, thin shell of titanium dioxide are synthesized via a remarkably simple one-pot route, where the reduction of Ag + to Ag 0 and the controlled polymerization of TiO2 on the surface of silver crystallites take place simultaneously. The prepared dispersions of coated nanoparticles display a surface plasmon band, which is significantly red-shifted with respect to that of bare Ag. Highquality ultrathin films of the core-shell clusters are prepared via layer-by-layer assembly. The nanoparticles are arranged in closely packed layers interlaced with polyelectrolyte producing a stratified core-shell hybrid material with unique structure and catalytic and electron-transport properties.

Three-dimensional colloidal crystals have been grown by electrophoretic deposition on ITO glass supports from aqueous-ethanol colloidal solutions of monodisperse submicrometer-sized negatively charged polystyrene latex spheres. The technique offers the possibility to produce uniform single-crystal colloidal multilayers on the time scale of minutes, which is a drastic acceleration in comparison with the gravity sedimentation technique that needs weeks or even months. SEM and AFM images of colloidal crystals reveal that close-packed 3D fcc ordering of the latex spheres extends over large areas. Electrophoretically deposited colloidal crystals show a pronounced photonic stopband in the visible spectral range in the normal incidence transmission spectra with a position depending on the size of latex spheres. The electrophoretic deposition has also been used for the impregnation of 3D colloidal crystals with luminescent CdTe nanocrystals. The luminescence spectrum of CdTe nanocrystals shows a dip at the wavelengths corresponding to the spectral position of the photonic stopband of the colloidal crystal.