ATTO 655 PEG3 azide

• Ex/Em: 661/679 nm
• Extinction Coefficient: 125,000 M⁻¹cm⁻¹
• Reactive Group: Azide
• Click Chemistry Conjugation: Efficiently labels terminal alkynes via CuAAC and copper-free SPAAC, perfect for peptides, antibodies, and biomolecules
• High Quantum Yield & Stability: Delivers bright, photostable fluorescence with strong thermal resilience
• Ozone-Resistant: Superior resistance to atmospheric ozone ensures reliable performance, ideal for microarray applications
• Hydrophilic PEG3 Spacer: Enhances solubility and minimizes steric hindrance for enhanced biocompatibility

ATTO 655 is a far-red fluorescent dye characterized by its strong absorption, high photo and thermal stability, and excellent ozone resistance. The dye exhibits enhanced aqueous solubility due to the incorporation of a PEG3 spacer 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.

The PEG3-azide derivative of ATTO 655 is widely used for labeling terminal alkynes on peptides, antibodies, and other biomolecules via click chemistry. It participates in copper-catalyzed azide-alkyne cycloaddition (CuAAC) with alkyne-containing molecules and strain-promoted alkyne-azide cycloaddition (SPAAC) with DBCO- or BCN-containing molecules.