greenfluorescent

Green fluorescence is the emission of light in the green portion of the visible spectrum by a fluorescent molecule after it absorbs higher-energy light. The typical emission range is about 495–530 nanometers. In practice, green fluorescence is produced by natural fluorophores or by fluorescent proteins and dyes used in biological assays. The compound called green fluorescent protein (GFP) is the best-known example, though many other green-emitting fluorophores exist.

Green fluorescent protein (GFP) was discovered in the jellyfish Aequorea victoria and has become a fundamental tool in biology. GFP emits green light without added substrates and can be fused to proteins to monitor their localization, expression, and dynamics in living cells. Variants such as enhanced GFP (EGFP) and other green-shifted derivatives extend brightness and maturation speed while maintaining emission in the green range.

Applications span fluorescence microscopy, live-cell imaging, flow cytometry, and high-content screening. GFP and related green fluorophores are often used in multicolor experiments alongside red and blue reporters. Limitations include photobleaching and pH sensitivity, and for older GFPs, dependence on molecular oxygen for chromophore maturation. Newer variants have improved brightness, maturation, and photostability, expanding the practical use of green fluorescence in research.