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Free keywords:
fluorescence; dyes; large Stokes shift; STED microscopy
Abstract:
The review deals with commercially available organic dyes possessing large Stokes shifts and their
applications as fluorescent labels in optical microscopy based on stimulated emission depletion
(STED). STED microscopy breaks Abbe’s diffraction barrier and provides optical resolution beyond
the diffraction limit. STED microscopy is non-invasive and requires photostable fluorescent markers
attached to biomolecules or other objects of interest. Up to now, in most biology-related STED
experiments, bright and photoresistant dyes with small Stokes shifts of 20–40 nm were used. The
rapid progress in STED microscopy showed that organic fluorophores possessing large Stokes shifts
are indispensable in multi-color super-resolution techniques. The ultimate result of the imaging
relies on the optimal combination of a dye, the bio-conjugation procedure and the performance
of the optical microscope. Modern bioconjugation methods, basics of STED microscopy, as well
as structures and spectral properties of the presently available fluorescent markers are reviewed
and discussed. In particular, the spectral properties of the commercial dyes are tabulated and
correlated with the available depletion wavelengths found in STED microscopes produced by LEICA
Microsytems, Abberior Instruments and Picoquant GmbH.
