Into colloidal particles formed from chitosan and DNA, microcrystallines of either H- or J-aggregates of astaxanthin have been selectively incorporated. Which form of the aggregate is produced in the nanoparticles is governed by the composition of ethanol-water solutions used for their preparations. These aqueous colloidal dispersions show large hypsochromic and bathochromic shifts, with respect to the monomeric dye, indicating strong potentials for medical and pharmaceutical applications.