(Figure ; Mightex ® High-Power LED Collimator Sources, 22 mm aperture, 490 nm, typical output power 140 mW.) The uncaging process was analyzed by HPLC-UV, showing ATP was cleanly released upon irradiation (Figure ). The uncaging kinetics were obtained from HPLC analysis (Table ), demonstrating almost full release of ATP within 7 minutes (Figure ). To evaluate the cellular uptake of molecules 15-22 (Scheme 1C), experiments were performed using HeLa cells. 1 mM stock solution in DMEM was added to dishes containing HeLa cells with a final concentration of 50 µM. Cells were incubated in the dark at 37 °C for 5h, then washed with PBS buffer and stained with CellMask™ deep red plasma membrane stain, which is compatible with the DEAC450 emission. Finally, cells were imaged with super-resolution microscopy (Elyra 7, Zeiss). The compounds 15-22 were stable under the applied conditions as judged by HPLC (Figure ).