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Atto labels represent a comprehensive series of fluorescent labels for biomolecules, which are designed for highest sensitivity applications. A unique combination of advantages makes them highly favorable tools for all kinds of labeling applications.
Features and Benefits
The absence of cis-trans-isomerization circumvents potential problems in Fluorescent Resonant Energy Transfer (FRET) or single molecule detection (for more details and references please see Analytix 8/2001)
Our range of labels show excitation and emission maxima spanning the range from 390 - 750 nm. This gives opportunity to use various sources of excitation light and to match emission light common used filter sets for other labels. Obviously it also allows a variation of multicolor visualization. The comparably small size of our labels (MW between 400 and 600) minimizes risk of unwanted steric effects towards the interaction of labeled molecules with other target structures. Furthermore Atto labels are quite insensitive against pH fluctuation - most of them do not show any effects between pH 2 and 10- and feature low unspecific adsorption.
Atto dyes are a series of fluorescent dyes, that provide all the crucial properties required for modern fluorescent technologies, such as fluorescence microscopy, flow cytometry, fluorescence in situ hybridisation (FISH), receptor binding assays, or enzyme assays.
Confocal micrograph of human endothelial cells (HUVAC) visualizing vimentin by indirect staining; anti-Vimentin (rabbit) followed by Atto-532 (green) conjugated anti-rabbit-antibody (goat). Counterstaining of cell nucleus by DAPI (blue).
Triple staining of human endothelial cells (HUVAC): vWillebrand factor was visualized with Atto 550 labelled antibody (green), Cadherin with Atto 655 labelled antibody (red) and nucleus by DAPI (blue).
All Atto labels are available as free fluorophores (which might be coupled via free COOH-groups) or succinimidyl (NHS-) esters, which can be coupled to proteins easily. Coupling procedures may be found on our product information sheets.
For convenient use of fluorescent labels in common assay formats we now also offer Atto labels conjugated to specific proteins, inlcluding Atto antibody conjugates. Biotin- and Streptavidin conjugates are the most commonly used among them. The high affinity of streptavidin (like avidin) to biotin has been the basis for wide spread use of streptavidin conjugates as secondary detection reagents in microscopy, flow cytometry, immunoassays, blot analysis and nucleic acid hybridization methods. Streptavidin was chosen as it shows much lower unspecific binding than avidin. Our streptavidin conjugates basically show same spectral spattern than unbound labels. An interesting feature is that several of our streptavidin conjugates show low fluorescence, but strong enhancement of fluorescence after binding to biotin. This phenomenon helps to improve sensitivity in case, that some conjugate might be left adsorbed unspecifically.
Atto labels are also available as Maleimides, which open up an alternative method to amino labelling. Maleimides are suitable for coupling to thiol containing groups such as those contained in cysteine residues. The same holds for thiol groups introduced as modifiers during automated synthesis (of for example oligonucleotides).
 Fluorescence intensity profile of single dye molecules (Atto 650) on a glass surface.
Product List(Standard Pack Size is 1 mg)
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