Lanthanide-chelate silica nanospheres as robust multicolor Vis-NIR tags.

Different lanthanide chelates have been simultaneously embedded in a silica matrix yielding bright dual-mode lanthanide doped nanospheres which are uniform in size distribution, tunable, photostable, and leakage free. Depending on the chelate combination, two color emission with a single light source or tunable emission with multiple sources is obtained.