Fluorene-derived two-photon fluorescent probes for specific and simultaneous bioimaging of endoplasmic reticulum and lysosomes: group-effect and localization

Two novel fluorene-derived two-photon fluorescent probes (TPFL) targeting the endoplasmic reticulum (TPFL-ER) and lysosomes (TPFL-Lyso) were synthesized by introducing a chlorine group and a morpholine group, respectively. They were shown to be suitable for specific and simultaneous imaging of the endoplasmic reticulum and lysosomes without affecting protein movements owing to their similar molecular structures. TPFL-ER and TPFL-Lyso were successfully used to visualize the changes of the endoplasmic reticulum and lysosomes during cancer cell apoptosis and they demonstrated high specificity and sensitivity, excellent photostability, and low phototoxicity.