FITC (fluorescein isothiocyanate)-conjugated anti-monkey primary antibodies are fluorescent immunoreagents that combine the green-emitting fluorescein fluorophore with the target specificity of immunoglobulins directed against non-human primate (NHP) antigens. These reagents are widely employed in flow cytometry, fluorescence-activated cell sorting (FACS), immunofluorescence microscopy, and fluorescence-based plate assays for sensitive detection of monkey immunoglobulins, cell surface markers, and other antigens in preclinical research, vaccine development, and translational medicine.

The FITC Fluorophore

Fluorescein isothiocyanate is a xanthene-based fluorescent dye with a molecular weight of approximately 389 Da. FITC is the most widely used fluorescein derivative for antibody conjugation, containing an isothiocyanate reactive group that enables covalent attachment to proteins. The dye exhibits maximal excitation at approximately 490–495 nm and maximal emission at 516–525 nm, producing bright green fluorescence. FITC has a molar extinction coefficient of approximately 73,000–75,000 cm⁻¹M⁻¹ at 488 nm and a quantum yield of approximately 0.85–0.92 when free in alkaline aqueous solution. However, the quantum yield decreases to 0.3–0.5 when fluorescein is conjugated to antibodies, a phenomenon that must be considered in quantitative applications.