ATTO 647N PEG3 azide

• Ex/Em: 645/663 nm
• Extinction coefficient: 150,000 cm^-1M^-1
• Reactive group: azide
• Click Chemistry Conjugation: Efficiently labels terminal alkynes via CuAAC and copper-free SPAAC, ideal for peptides, antibodies, and 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
• Hydrophilic PEG3 Spacer: Enhances solubility and minimizes steric hindrance for enhanced biocompatibility

ATTO 647N is a rhodamine-derived fluorescent dye specifically optimized for applications in the red spectral region. It exhibits spectral properties comparable to Cy5, with improved aqueous solubility conferred by a PEG3 spacer. The dye is characterized by a high molar absorptivity, robust fluorescence quantum yield, and superior thermal and photostability, making it a reliable choice for demanding experimental conditions. ATTO 647N is moderately hydrophilic and has an excitation maximum within the 625-660 nm range, which is well-suited for use with the 647 nm line of Krypton-Ion lasers and the 650 nm line of diode lasers. The dye retains consistent fluorescence across a wide pH spectrum (pH 2-11), ensuring its applicability in diverse biochemical and biophysical assays. Upon conjugation, ATTO 647N becomes cationic with a net positive charge of +1. Notably, this dye exhibits enhanced resistance to atmospheric ozone degradation compared to cyanine dyes, increasing its stability and reliability in microarray and other long-term applications. ATTO 647N is particularly suitable for high-precision techniques, including single-molecule detection, super-resolution microscopy (e.g., SIM, STED), flow cytometry (FACS), fluorescence in situ hybridization (FISH), and various other advanced biological and analytical methodologies.

The PEG3-azide derivative of ATTO 647N 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.