Label-free detection of exonuclease III by using dsDNA-templated copper nanoparticles as fluorescent probe

Abstract

3'-5' Exonuclease activities play key roles in maintaining genome stability, so the detection of 3'-5' exonuclease activity is very important for diseases diagnosis and drug development. In this paper, we established a simple, sensitive, low-cost and label-free method to detect the activity of exonuclease III (Exo III) by using double-strand DNA (dsDNA)-templated copper nanoparticles as fluorescent probe. Fluorescent Cu nanoparticles (NPs ) with maximum emission wavelength of 575 nm are formed by using double-strand DNA (dsDNA) as templates. Upon the addition of Exo III, the dsDNA templates would be digested from 3' to 5', and the formation of fluorescent Cu NPs would be inhibited. Thus, the fluorescence intensity of dsDNA-Cu NPs would decrease. This method exhibits a low detection limit of 0.02 U mL(-1) for Exo III. Compared with the previous reports, this method does not need complex DNA sequence design, fluorescence dye label and sophisticated experimental techniques.

Keywords: 3′–5′ exonuclease; Copper nanoparticles; DNA; Exonuclease III; Fluorescent sensor.