Unimolecular, amphiphilic polymeric nanocontainers based on poly(2-vinylpyridine)-b-polystyrene-polymacromonomers are dispersed in organic solvents and loaded with different hydrophilic dyes in solution. The poly-2-vinylpyridine core of the nanocontainers is responsible for the dye uptake, whereas the polystyrene corona grants the solubility and stabilization of the particles. The nanocontainers are 20-30 nm in diameter and possess an excellent ability to sequester dye molecules up to 116% (w/w) or 3.20 mmol/g. (c) 2005 Elsevier Ltd. All rights reserved.