Fluorescein di-beta-D-galactopyranoside

Fluorescein di-β-D-galactopyranoside (FDG) is a fluorogenic substrate used to detect β-galactosidase activity via flow cytometry, with excitation at 485 nm and emission at 535 nm. It is widely applied in both in vitro and in vivo research for studying gene expression and cell senescence in models ranging from kinetoplastids to mammalian cells.