荧光素5（6）-异硫氰酸酯，也称为FITC，是一种弱酸性的羟基黄酮类化合物，其整体尺寸较小，在苯环上具有羧酸和异硫氰酸酯基团。这种染料具有中等大小、非平面的芳香环系。 异硫氰酸酯基团与生物分子的亲核官能团（如氨基，羟基，巯基）反应，作为荧光标记物附加在生物分子上。 该染料在相同溶剂中的最大发射波长为519纳米。 应用 用于蛋白质的荧光标记（例如免疫荧光）;凝胶色谱中的 H 蛋白质标记 荧光素5(6)-异硫氰酸(FITC)标记的分子用于非显微免疫测定和生理示踪实验。FITC在流式细胞术实验中广泛用于蛋白质、细胞核和亚核颗粒的染色。 使用FITC标记的白细胞（WBC）可用于研究其对趋化因子的反应性并进行最终测定。 Fluorescein 5(6)-isothiocyanate, also known as FITC, is a weakly acidic hydroxyxanthene whose overall size is small, with both carboxylic acid and isothiocyanate substituents on the pendant phenyl ring. The dye has a moderately sized, nonplanar aromatic system. The isothiocyanate group reacts with nucleophilic substituents (e.g. amino, hydroxyl, thiol) of biomolecules to be attached as a fluorescent label. The maximum emission of the dye is at 519nm in the same solvent. Application Fluorescein 5(6)-isothiocyanate (FITC) labelled molecules are used in non-microscopic immunoassays and physiological tracing experiments. FITC is widely used in flow cytometry experiments for staining proteins, nuclei, and subnuclear particles. White blood cells (WBCs) are marked with FITC to study their response toward a chemoattractant, eventually being measured. For fluorescent labeling of proteins (e.g. immunofluorescence); H Protein labeling for gel chromatography