XFD405 PEG4 DBCO

• Ex/Em: 401/421 nm
• Extinction coefficient: 35,000 cm^-1M^-1
• Reactive Group: DBCO
• Copper-Free Bioorthogonal Labeling: Enables rapid and efficient azide conjugation via copper-free SPAAC
• Stable Fluorescence: Resists photobleaching, pH-insensitive from pH 4 to 10, and minimal quenching when conjugated to proteins
• Advanced PEG4 Spacer: Enhances solubility and minimizes steric hindrance for improved biocompatibility

XFD405, manufactured by AAT Bioquest, is a blue-fluorescent dye that is structurally identical to Alexa Fluor™ 405 (ThermoFisher). The incorporation of a PEG4 linker enhances its aqueous ability, and it is effectively excited by the 407 nm krypton laser line or the 408 nm violet laser diode, making it suitable for a range of fluorescence-based techniques. XFD405 is pH-insensitive across a wide range (pH 4 - 10) and exhibits minimal quenching when conjugated to proteins, ensuring consistent fluorescence signals in live-cell imaging. With an excitation maximum at 401 nm and emission at 422 nm, XFD405 is well-suited for multicolor flow cytometry and super-resolution microscopy (STORM), providing reliable performance in applications requiring distinct spectral separation and photostability.

The DBCO derivative of XFD405 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, XFD405 DBCO serves as an effective alternative to copper-dependent fluorescent alkynes.