5-[[[[2-[[(4S)-4-[[4-[[(2-氨基-1,4-二氢-4-氧代-6-蝶啶基)甲基]氨基]苯甲酰基]氨基]-4-羧基-1-氧代丁基]氨基]乙基]氨基]硫代甲酰]氨基]-2-(6-羟基-3-氧代-3H-氧杂蒽-9-基)苯甲酸钠盐

Folate receptor alpha

EC-17 contains the fluorescein fluorochrome and has a spectral wavelength of 490–530 nm. EC-17 is synthesized by a folate (vitamin B9) and fluorescein isothiocyanate (FITC) conjugated through an ethylenediamine spacer to produce folate-FITC, with a molecular weight of 917 kDa. FITC is a derivative of fluorescein functionalized with an isothiocyanate reactive group. The folate-FITC conjugate forms a negatively charged fluorescent molecule that specifically targets cell-surface FRα and is subsequently internalized into the cytoplasm. The signal-to-background ratio (SBR) of EC-17 for HeLa cells range from 0.97 to 7.32 depending on the molarity and concentration of cancer cells.

The mean fluorescence signal from the animals injected with EC-17 to be 42,234 ± 12,234 au. Fluorescence microscopy for folate-FITC shows a strong signal in all malignant tumors with FR-α expression and no signal in FR-α–negative malignant or benign lesions.