Luminescence Developments Help Scientists See The Light

Biologists are constantly seeking more sensitive assays to detect the presence of organisms or telltale DNA, RNA, and proteins. Although radioactive tags incorporated into the target itself (or into a complementary strand)-and later detected by Geiger counters or film exposures-have traditionally given good sensitivity, the problems of waste disposal and laboratory monitoring have driven a search for alternative tags that have radioactivity's sensitivity but avoid its hazards. Fluorescent tags-

James Kling
May 11, 1997

Biologists are constantly seeking more sensitive assays to detect the presence of organisms or telltale DNA, RNA, and proteins. Although radioactive tags incorporated into the target itself (or into a complementary strand)-and later detected by Geiger counters or film exposures-have traditionally given good sensitivity, the problems of waste disposal and laboratory monitoring have driven a search for alternative tags that have radioactivity's sensitivity but avoid its hazards.

Fluorescent tags-bound directly to the analyte-are easily disposable, but these reagents are not always sensitive enough to meet a researcher's needs (J. Kling, The Scientist, April 14, 1997, page 14). As a result, radiolabels continue to be a mainstay in many smaller research laboratories.

But where fluorescent tags fail, chemiluminescence and bioluminescence detection can often step in. These systems rely on a reporter enzyme-which signals the presence of the target and produces the luminescence-and a substrate, usually added separately. The...

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