What is luminescence?
Luminescence is the emission of light by a substance as a result of a chemical reaction (chemiluminescence) or an enzymatic reaction (bioluminescence).
Luminescence detection is optically simpler than fluorescence detection as it does not require a light source or specific optics for excitation.
Figure 1 - Flash and Glow reaction
Luminescence can be either a ‘flash’ or a ‘glow’ reaction, depending on the kinetic profiles. Flash luminescence gives a very bright signal for a short amount of time, usually seconds. Glow luminescence emits a more stable but usually less intense signal that can last for several minutes or hours. Flash luminescence generally requires a detection system with injectors that can deliver substrate to the reaction shortly before taking a measurement so that signal is not missed. White microplates are usually recommended for luminescence as they reflect light and maximize the signal. (see Figure 1)
Advantages of luminescence
Luminescence is an extremely popular detection platform for many applications compared to absorbance and fluorescence. It generally offers a wider dynamic range and a higher sensitivity as background interference (autofluorescence from compounds, media and cells) is low. In addition, luminescence assays often use a homogenous (no wash) protocol, which makes them simpler to automate for high-throughput applications.