Polymerization-sensitive switch-on monomer for terminal transferase activity assay.

We herein describe a simple but efficient method for the determination of terminal transferase (TdT) activity, which relies on our finding that Fe(III)-quenched boron-dipyrromethene (BODIPY)-ATP is utilized as a switch-on monomer for polymerization and enables the facile synthesis of fluorescence oligonucleotides without additional, post-processing steps. As TdT carries out the synthesis of DNA by adding the monomers into growing chains, Fe(III) is displaced from BODIPY with the release of pyrophosphate group, which consequently leads to the generation of highly fluorescent long oligonucleotides. With this strategy, we selectively detected the TdT activity with high sensitivity. In addition, its practical applicability was successfully demonstrated by determining TdT activities in human serum.