FSD EX Fluor™ 680 NHS Ester is a next-generation, amine-reactive near-infrared (NIR) fluorescent dye developed through BioActs’ advanced technology. It exhibits excellent optical performance and high brightness compared with spectrally similar dyes, making the FSD EX Fluor™ series ideal for diverse biochemical and biological applications.

FSD EX Fluor™ 680 shows excitation and emission maxima (Ex/Em = 679/696 nm) comparable to Alexa 680, Cy5.5, IRDye 680LT, and DyLight 680. The dye can be efficiently excited by a 633 nm laser line, emitting in the NIR region that provides superior tissue penetration and minimal background interference. It demonstrates high sensitivity and photostability suitable for advanced fluorescence imaging. The NHS ester form readily reacts with amine-modified oligonucleotides or primary amines—such as the ε-amino group of lysine or the terminal amine of nucleotides—to form a stable amide linkage. This enables efficient labeling of low-abundance biomolecules with strong, stable fluorescence signals. FSD EX Fluor™ 680 NHS Ester is optimized for both in vitro and in vivo NIR imaging applications.

Special Properties (NIR Characteristics)

FSD EX Fluor™ 680, 750, and 800 dyes emit within the near-infrared region (NIR-I, 650–900 nm), known as the optical window of biological tissues. In this spectral range, absorption and scattering by biomolecules such as hemoglobin, water, and lipids are minimal, allowing deep tissue penetration and low background autofluorescence. These dyes provide high signal-to-noise ratios and excellent photostability, making them ideal for in vivo and deep-tissue fluorescence imaging.