Fluorescent Rhodamines and Fluorogenic Carbopyronines for Super-Resolution STED Microscopy in Living Cells

A range of bright and photostable rhodamines and carbopyronines with absorption maxima in the range of =500-630nm were prepared, and enabled the specific labeling of cytoskeletal filaments using HaloTag technology followed by staining with 1m solutions of the dye-ligand conjugates. The synthesis, photophysical parameters, fluorogenic behavior, and structure-property relationships of the new dyes are discussed. Light microscopy with stimulated emission depletion (STED) provided one- and two-color images of living cells with an optical resolution of 40-60nm.