Poly(maleic anhydride-alt-1-octadecene), a cheap and commercially available polymer, was used to water-solubilize colloidal nanocrystals with various compositions, morphologies, and sizes. Highly pure nanoparticles with homogeneous distributions of sizes and surface charges were obtained after a single purification step of the polymer-coated particles by ultracentrifugation, saving precious time as compared to a previously published and similar polymer coating procedure. This simple strategy proved also to be generally applicable and represents a valid methodology to water-solubilize nanoparticles.