XFD700 PEG4 DBCO

• Ex/Em: 696/719 nm
• Extinction coefficient: 192,000 cm^-1M^-1
• Reactive Group: DBCO
• Copper-Free Bioorthogonal Labeling: Enables rapid and efficient azide conjugation via copper-free SPAAC
• Moderate Brightness: Suitable for high-abundance targets, preserving brighter dyes for low-abundance detection.
• Water Soluble: Minimizes aggregation, enhancing signal clarity for advanced imaging and live-cell studies
• Panel Optimization: Enhances spectral resolution between APC and APC-iFluor® 780 in multicolor assays.

XFD700, manufactured by AAT Bioquest, is a near-infrared fluorescent dye structurally identical to Alexa Fluor™ 700 (ThermoFisher). It is optimally excited by 633–640 nm laser lines and offers a relatively low fluorescence intensity, making it particularly well-suited for direct imaging of high-abundance targets in both microscopy and flow cytometry. This allows researchers to allocate brighter dyes for detecting lower-abundance antigens, improving overall panel design. XFD700 exhibits excellent aqueous solubility and maintains consistent fluorescence stability across a broad pH range (pH 4–10), ensuring robust and reproducible performance under diverse experimental conditions. Its long-wavelength emission effectively minimizes background autofluorescence, leading to enhanced signal-to-noise ratios, especially in complex biological samples such as tissues. In multicolor flow cytometry panels, XFD700 serves as an ideal option between APC and APC-iFluor® 780, enabling better resolution in complex assays.

The DBCO derivative of XFD700 is a highly reactive cycloalkyne optimized for copper-free click chemistry (SPAAC, strain-promoted azide-alkyne cycloaddition). This derivative exhibits a significantly higher reaction rate with azides compared to other cyclooctynes and copper-catalyzed click reactions (CuAAC). Uniquely, DBCO does not react with tetrazines, allowing for its use in bioorthogonal reactions alongside trans-cyclooctenes and tetrazines. For applications where the presence of copper is problematic, XFD700 DBCO serves as an effective alternative to copper-dependent fluorescent alkynes.