Years ago, researchers had only one data-imaging option: autoradiography. These scientists tagged samples—whether nucleic acid, protein, cell, or tissue—with radioactive labels, and captured images on film. Safety concerns, convenience, and sensitivity, spurred the development of alternative techniques, and today, researchers can choose from a range of options, including fluorescence, chemifluorescence, and chemiluminescence, in addition to autoradiography.

Fluorescence occurs when a fluorophore, such as fluorescein, absorbs light at one wavelength and emits it at another. Chemifluorescent reactions produce the fluorophore by chemical conversion of a fluorogenic substrate. Both types of fluorescent detection systems require an external light source, usually a laser.

Chemiluminescence is caused by a chemical reaction whose products glow without external stimulation. In many biological applications, an enzyme, linked to a detection antibody, catalyzes this reaction. Some chemiluminescent systems are based on the formation of peroxides by horseradish peroxidase, such as Piscataway, NJ-based Amersham Biosciences' ECL Plus™ reagent....

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