XFD594, manufactured by AAT Bioquest, is structurally similar to Alexa Fluor™ 594 (Thermo Fisher). This bright red-fluorescent dye is efficiently excited by the 561 nm or 594 nm laser lines 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. XFD594 is particularly well-suited for multicolor fluorescence microscopy, flow cytometry, and advanced SRM imaging techniques like dSTORM, SIM, STED and TPE. 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 XFD594 make it ideal for detecting low-abundance biological targets, enabling greater precision and sensitivity in quantitative fluorescence assays.

The N-hydroxysuccinimidyl (NHS) ester of XFD594 is a widely used reagent for the conjugation of this dye to proteins or antibodies. NHS esters react selectively and efficiently with primary amines (such as the side chains of lysine residues or aminosilane-coated surfaces) at pH 7–9, forming stable covalent amide bonds. This property makes XFD594 NHS ester an excellent choice for labeling proteins, amine-modified oligonucleotides, and other amine-containing molecules.