Optical enzyme assay with cell-penetrative molecules and a fluorogenic liposome will be discussed. Polyarginine (pR) can cross a lipid bilayer of a liposome when they are bound to amphiphilic anions. The cell-penetrative complexes can act as anion carriers, and their translocation activities can be monitored by fluorogenic release of carboxyfluorescein (CF) from LUVs-CF (large unilamellar vesicles loaded with CF). This finding implied that the optical transduction of enzyme reactions can be achieved. The presence of the competitive anions, such as ATP, that hinder the formation of pR-activator complex should cause reduced activity. The degradation of the inhibitor anion to the less-competitive anion by enzymatic reaction, for example, should therefore be easily detectable as increase in the activity of pR-activator complexes. We successfully introduced the optical transducer to universal enzyme reaction assay and to optical sensing of sucrose, lipids, etc.

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