ATTO 655 Tetrazine

• Ex/Em: 661/679 nm
• Extinction coefficient: 125,000 cm^-1M^-1
• Reactive group: Tetrazine
• Rapid Conjugation: Labels TCO-modified biomolecules under copper-free conditions with fast reaction kinetics
• High Quantum Yield & Stability: Provides bright fluorescence with high photostability and thermal resilience
• Ozone-Resistant: Enhanced resistance to atmospheric ozone degradation compared to cyanine dyes

ATTO 655 is a far-red fluorescent dye characterized by its strong absorption, high photo and thermal stability, excellent ozone resistance and excellent water solubility. The dye exhibits moderate hydrophilicity and is optimally excited within the 640-660 nm wavelength range, which aligns with the 647 nm line of Krypton-Ion lasers and the 650 nm line of diode lasers. As a zwitterionic compound, ATTO 655 remains electrically neutral when conjugated to biomolecules or other substrates. Its strong electron-accepting properties result in efficient fluorescence quenching by electron donors such as guanine and tryptophan. These properties render ATTO 655 highly suitable for precise applications including single-molecule detection and super-resolution microscopy techniques like PALM, dSTORM, and STED. Furthermore, ATTO 655 is compatible with flow cytometry (FACS), fluorescence in situ hybridization (FISH), and a variety of other biological assays, making it a versatile tool in advanced fluorescence-based research.

ATTO 655 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.