DNA-scaffolded silver nanoclusters as an on–off label-free fluorescence probe for the selective detection of endonuclease activity and inhibition

Abstract

A label-free platform method to selectively detect the activity and inhibition of EcoRI has been developed. This method was based on using DNA-templated silver nanoclusters (DNA–AgNCs) as the fluorescence probe and the fluorescence intensity of the long-chain DNA–AgNCs was stronger than the short one. In the assay, C-rich DNA was designed which contained twenty cytosine bases and G-rich DNA was complemented to it. In the presence of EcoRI, they hybridized and were cut by EcoRI, and finally the fluorescence of the DNA–AgNCs was quenched. This proposed assay was easy and convenient to operate in a homogeneous solution, with a high sensitivity and selectivity that enabled other endonucleases to be distinguished. The limit of detection of EcoRI was 2.1 × 10⁻⁴ U μL⁻¹. Meanwhile, this method used DNA–AgNCs as the fluorogen which is label-free and cheap. Our method was also able to determine the inhibition of EcoRI; it has potential applications in drug screening assays.