NOVELTY - Stabilization of quantum size-dependent properties of nanocrystals and provision of colloidal stability of the nanoparticles in a liquid comprises preparing a polymer multidentate ligand and dissolving the ligand in a fluid. The polymer multidentate ligand has first portions which can bind to a surface of the nanoparticles and a second portion which does not bind to the surface of the nanoparticles.    USE - The method is for stabilization of quantum size-dependent properties of nanocrystals and provision of colloidal stability of nanoparticles in a liquid, where nanoparticles are luminescent nanocrystals, particularly semiconductor nanocrystals consisting of silicon, germanium, indium phosphide, gallium arsenide, cadmium selenide, cadmium telluride, lead sulfide, lead selenide, zinc selenide, zinc sulfide, cadmium sulfide, silver sulfide, copper sulfide or titanium dioxide (most preferably cadmium selenide/zinc sulfide quantum nanocrystals), especially core-shell nanocrystals (all claimed). They are useful for biological labels; solar cells; photoluminescence polymer composites (e.g. for lasers). The method is used to print security markings and barcodes that absorb and/or emit light at UV and/or visible wavelengths.    ADVANTAGE - The method establishes the utility of using simple homopolymers or copolymers, which can be synthesized in a controlled manner, as robust multidentate ligands.    DETAILED DESCRIPTION - Stabilization of quantum size-dependent properties of nanocrystals and provision of colloidal stability of the nanoparticles in a liquid comprises:    (a) preparing a colloidal dispersion of nanoparticles in a liquid, preparing a polymer multidentate ligand having first portions, which can bind to a surface of the nanoparticles and a second portion, which does not bind to the surface of the nanoparticles and dissolving the ligand in a fluid; and    (b) mixing the fluid containing the polymer with the colloidal dispersion of nanoparticles under conditions to induce binding of at least some of the first portions of the polymer multidentate ligand onto the surface of the nanoparticles, the polymer multidentate ligand being selected such that at least some of the first portions bind to the surface to stabilize quantum size-dependent properties of the nanocrystals and the second portion, which does not bind to the surface, provides colloidal stability of the nanoparticles in a desired liquid.