This invention provides composite materials comprising nanostructures (e.g., nanowires, branched nanowires, nanotetrapods, nanocrystals, and nanoparticles). Methods and compositions for making such nanocomposites are also provided, as are articles comprising such composites. Waveguides and light concentrators comprising nanostructures (not necessarily as part of a nanocomposite) are additional features of the invention.