Lanthanide-based protease activity sensors for time-resolved fluorescence measurements

Lanthanide-based luminescent sensors are noteworthy because their long-lifetime luminescence enables time-resolved fluorescence measurements. After exploring suitable antenna groups, we designed and synthesized lanthanide-based luminogenic sensors detecting protease activities. This sensor yielded strong luminescence on addition of proteases such as calpain I and leucine aminopeptidase (LAP). Since the luminescence lifetimes of the probes were very long, the sensors could be applied to time-resolved measurements that exclude background fluorescence signals derived from proteins or other impurities. This sensing principle could be applicable to general time-resolved fluorescence assays for other proteases.