Silica nanobubbles containing an organic dye in a multilayered organic/inorganic heterostructure with enhanced luminescence

We report the preparation, luminescent properties, and bioimaging applicati ons of a novel zinc sulfide (core)-two-photon dye-silica (shell) multilayer ed heterostructure. The method utilizes reverse micelles synthesis involvin g multistep reactions as a result of which composite nanoparticles having d ifferent sizes and morphology can be obtained. The size of these composite nanoparticles is typically 15-30 nm. An increase in the luminescence intens ity (similar to 70 times higher) and in fluorescence Lifetime is observed f or the dye encapsulated within the silica nanobubble. Photobleaching result s indicate that the dye is truly encapsulated and the silica shell provides a barrier to penetration of oxygen, thereby making the dye more photostabl e. The application of these particles as nanoprobes for bioimaging of cells using two-photon laser scanning microscopy is also presented.