Small, Stoichiometric & Reproducible labeling
FluoTag® is NanoTag’s trademark for camelid single-domain antibodies conjugated to chemical fluorophores. Using site-specific coupling chemistry, we ensure a uniform labeling stoichiometry and a defined localization of the fluorophore(s) on the sdAb. After chemical fluorophore attachment, the excess dye is carefully removed from the preparation. These production hallmarks ensure the best possible quality for low background and highest reproducibility. Together with the high-affinity monovalent binding mode of our sdAbs, these features provide a highly linear and reliable signal in all fluorescence-based analyses. In addition, due to the small size of sdAbs, all FluoTag® reagents show much better and more rapid tissue penetration as compared to conventional antibodies. This relates to both, access to crowded cellular environments and fast and deep penetration in 3D tissue sections and whole-mount samples.
Our FluoTags are available in up to three different flavors:
FluoTag®-Q: One target – One sdAb – One fluorophore (1:1:1)
All FluoTag®-Q reagents are conjugates featuring exactly one nanobody per fluorophore. The fluorophore is placed very near (< 1.5 nm) the antigen-binding surface.
- High affinity monovalent binding + one nanobody per fluorophore – Ideal for epitope counting and highly linear quantitative analyses
- Small size for optimal access to the target epitope, also in crowded environment or 3D samples.
- Minimal fluorophore displacement – ideal for super-resolution imaging at highest possible resolution
FluoTag®-X2: One target – One sdAb – Two fluorophores (1:1:2)
FluoTag®-X2 reagents are composed of a single sdAb carrying two fluorophores per protein molecule. The conjugate is therefore up to 2-fold (“X2”) brighter than the corresponding FluoTag®-Q products. The maximal displacement of fluorophores from the antigen-binding surface is ~3 nm. FluoTag®-X2 reagents are only slightly larger than the corresponding FluoTag®-Q products and therefore show similarly good tissue penetration features.
- High affinity monovalent binding + two fluorophores per sdAb for brighter signals
- Reagent is made from small-sized proteins. This ensures optimal access to the respective target protein, also in crowded environment or 3D samples.
Very low fluorophore displacement from the bound target protein – ideal for standard superresolution technologies
FluoTag®-X4: One taget – Two sdAbs – Four fluorophores (1:2:4)
Each FluoTag®-X4 reagent is a blend of two different sdAbs (FluoTag®-X2 and FluoTag®-X2-B) molecules that independently bind the target protein. As each sdAb carries two fluorophores per protein molecule, the blend can direct up to 4 fluorophores to each target protein. The reagent is therefore up to 4-fold (“X4”) brighter than the corresponding FluoTag®-Q products. The maximal displacement of fluorophores from each antigen-binding surface is ~3 nm. FluoTag®-X4 reagents have the same size as the corresponding FluoTag®-X2 products and therefore show similarly good tissue penetration features.
- A blend of two high affinity monovalent sdAbs directs four fluorophores to each target protein – ideal for bright signals
- Small size for optimal access to the respective target protein, also in crowded environment or 3D samples.
- Very low fluorophore displacement from the bound target protein – ideal for standard super-resolution technologies