One facile fluorescence strategy for sensitive detection of endonuclease activity using DNA-templated copper nanoclusters as signal indicators

Abstract Assay of endonuclease activity plays an important role in biologic and medicinal study. Herein, a simple and facile strategy was developed for detecting endonuclease activity. In this strategy, poly(AT-TA) double-stranded DNA containing restriction cutting site for EcoRI endonuclease was rationally designed and acted as the substrate of EcoRI and the template for copper nanoclusters (CuNCs). In the presence of EcoRI, the double-stranded DNA was cleaved, and then the introduction of Cu 2+ and ascorbate cannot form the fluorescent CuNCs due to the lack of the double-stranded DNA templates. The endonuclease actvity was quantified by monitoring the change in fluorescence intensity. Under the optimized conditions, the fluorescence change was linear with EcoRI concentration in the range from 0.002 U/μL to 0.1 U/μL with the detection limit of 0.00087 U/μL. This method was easy and convenient to operate in homogeneous solution, and the whole assay process can be completed in a single tube.