ATTO 647N Tetrazine

• Ex/Em: 645/663 nm
• Extinction coefficient: 150,000 cm^-1M^-1
• Reactive group: Tetrazine
• Click Chemistry Conjugation: Provides rapid, copper-free labeling of TCO-modified biomolecules
• High Quantum Yield & Stability: Provides bright fluorescence with high photostability, thermal resilience, and pH insensitivity across 2–11
• Ozone-Resistant: Enhanced resistance to atmospheric ozone degradation compared to cyanine dyes

ATTO 647N is a rhodamine-based fluorescent dye optimized for use in the red spectral region, with similar spectral characteristics as Cy5. It is characterized by high molar absorptivity, a strong fluorescence quantum yield, and excellent thermal and photostability. The dye is moderately hydrophilic and exhibits optimal excitation within the 625-660 nm range, making it compatible with the 647 nm line of Krypton-Ion lasers and the 650 nm line of diode lasers. ATTO 647N maintains stable fluorescence across a broad pH range (pH 2-11), supporting its application under diverse experimental conditions. Upon conjugation to a substrate, the dye becomes cationic, carrying a net positive charge of +1. Unlike cyanine dyes, ATTO 647N demonstrates enhanced resistance to atmospheric ozone degradation, which increases its reliability in microarray applications. ATTO 647N is particularly effective for high-precision applications such as single-molecule detection, super-resolution microscopy techniques (e.g., SIM and STED), flow cytometry (FACS), fluorescence in situ hybridization (FISH), and various other biological assays.

ATTO 647N tetrazine is particularly useful for labeling TCO-modified biomolecules under copper-free conditions. It reacts with TCO-functionalized molecules, forming a stable conjugate via a dihydropyrazine moiety. This click reaction is favored over others due to its extremely fast kinetics and higher yields under mild reaction conditions, making it a popular choice for researchers.