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Free keywords:
fluorescence, photoactivation, stimulated emission depletion (STED), optical superresolution, protein labelling, immunofluorescence
Abstract:
The use of photoactivatable dyes in STED microscopy has so far been limited by two—photon activation through the STED beam and by the fact that photoactivatable dyes are poorly solvable in water. Here we report ONB‐2SiR, a fluorophore that can be both photoactivated in the UV and specifically de‐excited by STED at 775 nm. Likewise, we introduce a conjugation and purification protocol to effectively label primary and secondary antibodies with moderately water‐soluble dyes. Greatly reducing dye aggregation, our technique provides a defined and tunable degree of labeling, and improves the imaging performance of dye conjugates in general.