XFD660 NHS Ester [equivalent to Alexa Fluor(R) 660 NHS Ester]

Extinction coefficient (cm^-1 M^-1): 132000. Excitation (nm): 663. Emission (nm): 691. XFD660, synthesized by AAT Bioquest, shares the exact same chemical structure with Alexa Fluor(R) 660 (a ThermoFisher trademark). This far-red dye is optimized for excitation by the 633 or 647 nm laser lines, making it well-suited for applications in imaging and flow cytometry where bright and photostable signal generation is critical. XFD660 is water-soluble and demonstrates pH stability within a range from 4 to 10. The NHS ester derivative of XFD660 is predominantly employed for conjugation to proteins or antibodies. This functionality allows the NHS ester to covalently attach to the primary amines present in proteins, amine-modified oligonucleotides, and other amine-bearing molecules. Conjugates utilizing XFD660 are noted for their enhanced fluorescence intensity and increased photostability relative to conjugates using other fluorophores with similar spectral characteristics.