Bioluminescence is generally said to be useful as an optical readout of various bioassays, by virtue of non-toxicity and simplicity in the measuring instrumentation.

Bioluminescence has low background intensity and works as highly sensitive optical readouts, compared to fluorescence. Meanwhile, bioluminescence has the poor absolute intensities and limitation in the color palette. If we address the limitations on the luminescence technology, we can fabricate much high-performance bioassays and thus can expect great impacts on a broad range of research fields ranging from basic biomedicine to industries.

The researchers developed a variety of bioluminescence substrates (native coelenterazine, nCTZ) which were conjugated by fluorescent dyes through co-works with Keio university. They have achieved a variety of luminescence colors through reacting the made substrates with AIST original Artificial Luciferases (ALuc®; AIST trademark) and Renilla luciferases (RLuc). The color variety is due to a resonance energy transfer from the luminescence substrates to fluorescent dyes (termed Chemiluminescence/Bioluminescence Resonance Energy Transfer (CRET/BRET)).

As some of the new substrates are selective to a specific luciferase, we can selectively visualize a luciferase activity even in a complex context of chemical substances. Especially, the researchers found that a substrate with an azide group as an intermediate for introducing a fluorescent dye, emits very bright green luminescence with unique enzyme specificity. The present achievements have wide utilities in the development of highly sensitive diagnosis kits, early detection of carcinomas, various bioassays, imaging of living subjects, etc.