Bioorthogonal, twice-clickable fluorogenic probes for two-photon live-cell microscopy.

Two-photon-excitable profluorogenic probes capable of undergoing bioorthogonal reactions in complex biological media remain exceedingly rare, despite their tremendous potential for live-cell imaging. We herein describe two new acridane-based probes capable of undergoing double bioorthogonal click reactions with cyclooctynes and exhibiting promising photophysical properties for live-cell imaging.