Alexander Zilles

New fluorescent markers for the red region

Two new classes of fluorescent dyes have been developed as labels for the red region of the spectrum: amide-bridged benzopyrylium dyes and carbopyronin dyes. The fluorescence quantum yield ranges from 20 to 90%, the decay time from 1 to 4 ns. The pH- and solvent-dependence of absorption and fluorescence are described in detail. Covalent attachment is possible via activated carboxyl groups.

Characterization of new fluorescent labels for ultra-high resolution microscopy

Photo-induced switching of dyes into dark, long-lived states, such as a triplet state, has recently gained increasing interest, as a means to achieve ultra-high optical resolution. Additionally, these long lived states are often highly environment-sensitive and their photodynamics can thus offer additional independent fluorescence-based information. However, although providing a useful mechanism for photo-induced switching, the triplet state often appears as a precursor state for photobleaching, which potentially can limit its usefulness. In this work, a set of rhodamine and pyronin dyes, modified by substitution of heavy atoms and nitrogen within or close to the central xanthene unit of the dyes, were investigated with respect to their triplet state dynamics and photostabilities, under conditions relevant for ultra-high resolution microscopy. Out of the dyes investigated, in particular the rhodamine and pyronin dyes with a sulfur atom replacing the central oxygen atom in the xanthene unit were found to meet the requirements for ultra-high resolution microscopy, combining a prominent triplet state yield with reasonable photostability.

Characterization of new fluorescent labels for ultrahigh resolution microscopy

A set of modified dyes was investigated, of which several candidates combine prominent triplet state yield with reasonable photostability. They can be used to achieve ultrahigh optical resolution by photo-induced switching into dark (triplet) states.