Surface functionalized perovskite nanocrystals: a design strategy for organelle-specific fluorescence lifetime...

Fluorescent molecules or materials with high photoluminescence quantum yields and stability towards photobleaching are ideally suited for multiplex imaging. Despite complying with such properties, perovskite nanocrystals (Pv-NCs) are rarely used for bioimaging owing to their toxicity and limited stability in aqueous media and towards human physiology. We aim to address these deficiencies by designing core-shell structures with Pv-NCs as the core and surface-engineered silica as the shell (SiO₂@Pv-NCs) since silica is recognized as a biologically benign carrier material and is known to be excreted through urine. The post-grafting methodology is adopted for developing [SiO₂@Pv-NCs]tpm and [SiO₂@Pv-NCs]tsy (tpm: triphenylphosphonium ion, tsy: tosylsulfonamide) for specific imaging of mitochondria and endoplasmic reticulum (ER) of the live HeLa cell, respectively. A subtle difference in their average fluorescence decay times ([SiO₂@Pv-NCs]tpm: ^tpm τ _av = 3.1 ns and [SiO₂@Pv-NCs]tsy: ^tsy τ _av = 2.1 ns) is used for demonstrating a rare example of perovskite nanocrystals in fluorescence lifetime multiplex imaging.