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

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