A submicron structure includes a silica body defining a plurality of pores that are suitable to receive molecules therein, the silica body further defining an outer surface between pore openings of said plurality of pores; and a plurality of anionic molecules attached to the outer surface of the silica body. The anionic molecules provide hydrophilicity to the submicron structure and are suitable to provide repulsion between other similar submicron structures, and the submicron structure has a maximum dimension less than one micron.