The invention relates to particles comprising: at least one ionically-charged water-soluble polymer; at least one surfactant having an ionic charge opposite to that of said polymer; and at least one water-soluble block copolymer having at least one non-ionic hydrophilic block and at least one non-ionic hydrophobic or ionic block. The invention also relates to a method of obtaining such particles consisting in: preparing a first aqueous mixture comprising the water-soluble, ionically-charged polymer and, if necessary, the water-soluble block copolymer if said copolymer has the same charge; subsequently, a second mixture is added to the above mixture, said second mixture comprising the surfactant and, if necessary, the water-soluble block copolymer if said copolymer has the same charge as the surfactant or if it is not ionically charged. Furthermore, the invention relates to the use of water-soluble block copolymers as an agent for stabilizing particles with a mesophase-forming internal structure, the internal structure of the resulting particles forming the same mesophase.