Facile Synthesis, Enhanced Photostability, and Long-term Cellular Imaging of Bright Red Luminescent Organosilica Nanoparticles.

We herein demonstrate a facile approach for the preparation of red luminescent organosilica nanoparticles (OSi NPs) via the addition reaction of indocyanine green (ICG) and (3-aminopropyl)trimethoxysilane (APTMS). Photoluminescent quantum yield (PLQY) of the resulting OSi NPs was tunable by simply changing the molar ratio of ICG and APTMS used in the reactions. Under the optimized molar ratio of ICG and APTMS, that is, 1:4, PLQY of the red luminescent OSi NPs was as high as 32%. The resulting OSi NPs presented greatly enhanced photostability, attributing to the promoted decay rate of the excited state and thus suppressed the generation of the reactive oxygen species in the OSi NPs. The integrated superiorities of high PLQY, enhanced photostability, low toxicity, and excellent biocompatibility endow the red luminescent OSi NPs extremely promising for long-term cellular imaging.