Long‐Term Live‐Cell STED Nanoscopy of Primary and Cultured Cells with the Plasma Membrane HIDE Probe DiI‐SiR

Super-resolution imaging of live cells over extended time periods with high temporal resolution requires high-density labeling and extraordinary fluorophore photostability. Here we achieve this goal by combining the attributes of the high-density plasma membrane probe DiI-TCO and the photostable STED dye SiR-Tz. These components undergo rapid tetrazine ligation within the plasma membrane to generate the HIDE probe DiI-SiR. Using DiI-SiR, we visualized filopodia dynamics in HeLa cells over 25 min at 0.5 sec temporal resolution, and visualized dynamic contact-mediated repulsion events in primary mouse hippocampal neurons over 9 min at 2 sec temporal resolution. HIDE probes such as DiI-SiR are non-toxic and do not require transfection, and their apparent photostability significantly improves the ability to monitor dynamic processes in live cells at super-resolution over biologically relevant timescales.