XFD430, manufactured by AAT Bioquest, is a green-fluorescent dye that is structurally similar to Alexa Fluor™ 430 (Thermo Fisher). It has excitation and emission maxima of 432 nm and 540 nm, respectively, and is efficiently excited by a 405 nm violet laser. Its large Stokes shift minimizes spectral overlap with blue-emitting fluorophores, significantly improving the signal-to-noise ratio in multiplexed fluorescence assays. XFD430 also exhibits excellent water solubility and remains pH-insensitive across a wide range (pH 4–10), making it well-suited for generating stable, reproducible fluorescence signals in both microscopy and flow cytometry applications.

The maleimide derivative of XFD430 is widely used for labeling biomolecules with free thiol (SH) groups, including antibodies, proteins, thiol-modified oligonucleotides, and low molecular weight ligands. Maleimides react readily with sulfhydryl groups, forming stable thio-ether bonds between the dye and the biomolecule, facilitating robust and reliable labeling for diverse experimental applications.