ATTO 550 Dye Labeling

ATTO® 550 is a premium orange fluorescent dye developed for high-performance fluorescence imaging, molecular diagnostics, and analytical applications. The dye combines high fluorescence quantum yield, excellent brightness, and outstanding resistance to photobleaching, making it an excellent choice for demanding fluorescence experiments requiring stable and sensitive signal detection.

ATTO 550 consists of three isomers with practically identical absorption and fluorescence. The fluorescence is excited most efficiently in the range 540 - 565 nm. They dye can be use as an alternative dye for Alexa flour 555 or NED fluorescent dye. 

Features:

• Replacement dye for TAMRA, CY3
• High Fluorescence yield
• High thermal and photo-stability
• Moderate hydrophilic
• Cationic dye
• Mixture of three diastereomers

ATTO® 550 is commonly conjugated to DNA, RNA, PNA, LNA, siRNA, antisense oligonucleotides (ASOs), aptamers, peptides, proteins, and other amino-modified biomolecules using NHS ester chemistry, forming a stable amide bond with primary amino groups. Alternative conjugation approaches, including click chemistry and other orthogonal labeling methods, can also be employed depending on the experimental design.

The dye exhibits excitation and emission maxima of approximately 554 nm and 576 nm, respectively, making it highly compatible with 543 nm, 552 nm, and 561 nm laser systems commonly found on confocal microscopes, fluorescence microscopes, imaging systems, and flow cytometers. ATTO® 550 provides excellent spectral separation from blue, green, red, and far-red fluorophores, making it particularly valuable for multicolor fluorescence imaging and multiplex assays.

ATTO 550 dye can be incorporated at any position within an Oligonucleotide. A primary amine modified oligonucleotide is used to covalently attach with dye via NHS conjugation chemistry; other cross-linking chemistries are also available depending on particular project specifications. Dual HPLC purification is used to remove failure sequences during first HPLC purification,  after labeling, the second HPLC is performed to remove unlabeled oligonucleotides and excessive dye in order to obtain a full length labeled oligonucleotide.

Bio-Synthesis offers custom ATTO® 550-labeled oligonucleotides for DNA, RNA, PNA, LNA, siRNA, ASOs, molecular beacons, aptamers, and other synthetic nucleic acids. ATTO® 550 can be incorporated at the 5′ end, 3′ end, or internal amino-modified positions, and may be combined with numerous additional modifications including quenchers, biotin, thiol modifiers, amino modifiers, PEG linkers, click chemistry handles, GalNAc, cholesterol, peptide conjugates, lipid conjugates, and other custom chemistries.

Each labeled oligonucleotide is synthesized under stringent quality standards and is available with optional HPLC purification, together with analytical characterization by HPLC, LC-MS, MALDI-TOF, UV-Vis spectroscopy, and fluorescence analysis to verify labeling efficiency, sequence identity, and product purity.

Property	Typical Value
Fluorophore	ATTO® 550
Fluorescence Color	Orange
Typical Reactive Group	NHS ester (or other conjugation formats)
Target Functional Group	Primary amino groups
Bond Formed	Stable amide bond
Excitation Maximum	554 nm
Emission Maximum	576 nm
Laser Compatibility	543 nm, 552 nm and 561 nm lasers
Filter Compatibility	Cy3 / TRITC filter sets
Compatible Oligos	DNA, RNA, PNA, LNA, siRNA, ASO, Aptamers
Typical Labeling Sites	5′ end, 3′ end, internal amino modifiers

Trademark Notice: ATTO® is a registered trademark of ATTO-TEC GmbH. Bio-Synthesis provides custom conjugation services using customer-specified or commercially available fluorescent dyes and is not affiliated with or endorsed by ATTO-TEC GmbH.