Fluorophore-free luminescent organosilica nanoparticles

In this paper, we report the preparation and characterization of fluorophore-free luminescent organosilica nanoparticles (NPs) with sizes varying from 50 to 250 nm. These NPs were synthesized by the Stöber method by incorporating several organosilanes together with the silicate precursor (tetraethyl orthosilicate, TEOS) to the silica matrix. The calcination of these NPs at high temperatures (600 and 700 degrees C) led to fluorescent and phosphorescent properties, which proved to be highly dependent on the initial composition of the silanization mixture and the heating temperature. Further characterization of this material in terms of its structural and optical properties is reported. Although the NPs are not very bright, the lifetime measurements revealed values in the millisecond range, which makes these NPs potentially attractive as luminescent materials and for time-resolved optical spectroscopic studies and bioassays.