XFD568 PEG4 DBCO

• Ex/Em: 579/603 nm
• Extinction coefficient: 91,300 cm^-1M^-1
• Reactive Group: DBCO
• Copper-Free Bioorthogonal Labeling: Enables rapid and efficient azide conjugation via copper-free SPAAC
• Bright & Stable: Provides high quantum yield with resilience to photobleaching and pH variations from 4 to 10
• Hydrophilic PEG4 Spacer: Enhances solubility and minimizes steric hindrance for enhanced biocompatibility

XFD568, manufactured by AAT Bioquest, is structurally identical to Alexa Fluor™ 568 (ThermoFisher). This bright orange-fluorescent dye is efficiently excited by the 568 nm line of the AR-Kr mixed-gas laser and is compatible with RFP filters like Texas Red. It demonstrates excellent solubility in aqueous solutions and is pH-insensitive across a broad range (pH 4–10), ensuring reliable and stable signal generation under diverse experimental conditions. XFD568 is particularly well-suited for multicolor fluorescence microscopy, flow cytometry, and advanced imaging techniques like dSTORM. It can be conjugated to proteins at high molar ratios with minimal self-quenching, resulting in brighter conjugates. Moreover, the superior fluorescence quantum yield and photostability of XFD568 make it ideal for detecting low-abundance biological targets, enabling greater precision and sensitivity in quantitative fluorescence assays.

The DBCO derivative of XFD568 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, XFD568 DBCO serves as an effective alternative to copper-dependent fluorescent alkynes.