Label-Free Rapid and Simple Detection of Exonuclease III Activity with DNA-Templated Copper Nanoclusters

In this study, DNA-templated copper nanoclusters (DNA-CuNCs) were used to detect exonuclease III (Exo III) activity, which is important for the diagnosis and therapy of several diseases. The results of this study showed that Exo III was affected by the concentrations of magnesium ions and sodium ions, and its optimal conditions for cleavage were 5 mM Mg2+ and less than 25 mM Na+. With a blunt-end DNA, more than 98% of DNA was digested by Exo III. As expected, with two or four cytosines in the terminal position of a 4-base overhanging DNA such as 5'-GGCC-3' and 5'-CCCC-3', there was little cleavage by Exo III compared with a blunt-end DNA.