XFD514 PEG4 DBCO

• Ex/Em: 518/543 nm
• Extinction coefficient: 80,000 cm^-1M^-1
• Reactive Group: DBCO
• Copper-Free Bioorthogonal Labeling: Enables rapid and efficient azide conjugation via copper-free SPAAC
• Bright and Stable: Offers high fluorescence intensity, photostability, and consistent performance across pH 4—10
• Advanced PEG4 Spacer: Enhances solubility and minimizes steric hindrance for improved biocompatibility

XFD514, manufactured by AAT Bioquest, is a bright green-fluorescent dye that is structurally identical to Alexa Fluor™ 514 (ThermoFisher). With optimal excitation between 480-535 nm, it is ideally compatible with the 488 nm line of the Argon-Ion laser and the 532 nm line of the frequency-doubled Nd:YAG laser. XFD514 demonstrates enhanced water solubility due to the incorporation of a PEG4 linker and remains stable over a wide pH range (pH 4–10), providing consistent and robust fluorescence signals. These properties make it highly suitable for advanced imaging techniques such as fluorescence microscopy and flow cytometry. XFD514 is a suitable replacement for rhodamine 6G.

The DBCO derivative of XFD514 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, XFD514 DBCO serves as an effective alternative to copper-dependent fluorescent alkynes.