Fluorescence is used in life sciences research as a non-destructive way of tracking or analyzing biological molecules. Some proteins or small molecules in cells are naturally fluorescent; this is called intrinsic or autofluorescence and includes molecules such as NADH, tryptophan or endogenous Chlorophyll, Phycoerythrin, or green fluorescent protein. Alternatively, proteins, nucleic acids, lipids, and small molecules can be labelled with an extrinsic fluorophore, a fluorescent dye which can be a small molecule, protein, or quantum dot.
Generally, fluorescent labels are advantageous compared to traditional radioactive and many biochemical labels. They are safer to work with; different fluorescent labels can be distinguished from one another allowing multiple biomolecules to be studied simultaneously; and certain properties of fluorescent labels can be exploited to detect proximity (fluorescence resonance energy transfer) or evaluate structure (fluorescence intensity). However, fluorescent labels can be toxic to tissue and cells and fluorescence can be quenched with repeated or extended exposure to light.
Direct immunofluorescence, a method that uses an antibody tagged with a fluorescent dye, can be used to detect the presence of a specific antigen, which is generally representative of the presence of a specific protein, in a biological sample. This laboratory test that is used to detect rabies in animals is a direct immunofluorescence assay.
To learn more about bioanalytical systems, equipment, instruments and software from Molecular Devices that can be leveraged for fluorescence detection, including intrinsic or extrinsic fluorescence, visit the links below.
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