Ru-catalyzed deprotection of 2.5 μM ©4 in CEF cells: (a) ©4, 30 min at 37 °C, blue channel; (b) ©4, 30 min at 37 °C, brightfield; (c) ©4 treated with 2.5 μM [Ru] and 100 μM PhSH, 8 min, blue channel; (d) ©4 treated with 2.5 μM [Ru] and 100 μM PhSH, 8 min, brightfield; (e) ©4 treated 20 min with 2.5 μM [Ru] and 100 μM PhSH, 20 min, blue channel; (f) ©4 treated 20 min with 2.5 μM [Ru] and 100 μM PhSH, 20 min, brightfield. (g) control with 2.5 μM 4 after 30 min at 37 °C, blue channel; (h) control with 15 μM 4 after 30 min, 37 °C, blue channel. Blue channel fluorescence microscopy settings: excitation filter 360–370 nm, emission filter 420 nm and dichromatic mirror 400 nm.