摘要

A "turn-on" and label-free fluorescent assay for the specific, rapid, and sensitive detection of 3'aEuro parts per thousand a dagger'aEuro parts per thousand 5' exonuclease III activity is reported in this study. The assay is based on the Tb3+-promoted G-quadruplex, which lead to the enhancement of Tb3+ fluorescence due to the energy transfer from guanines. The proposed assay is highly simple, rapid, and cost-effective, and does not require sophisticated experimental techniques such as gel-based equipment or radioactive labels. It can be used for the rapid detection of exonuclease III activity with a detection limit of 0.8 U and a RSD (n = 6) < 5 %. Notably, no dye was covalently conjugated to the DNA strands, which offers the advantages of low-cost and being interference-free.