Simultaneous Imaging of Zn2+ and Cu2+ in Living Cells Based on DNAzyme Modified Gold Nanoparticle

Trace Zn2+ and Cu2+ in living cells play important roles in the regulation of biological function. It is significant to simultaneously detect the cellular Zn2+ and Cu2+. Here, we present a novel two-color fluorescence nanoprobe based on the DNAzymes for simultaneous imaging of Zn2+ and Cu2+ in living cells. The probe consists of a 13 nm gold nanoparticle, DNAzymes that are specific for Zn2+ and Cu2+, and the substrate strands labeled with fluorophores at the 5' end and quenchers at the 3' end. The fluorescence of the fluoreophores is quenched both by the gold nanoparticle and the quencher. After the nanoprobes are transferred into the cells, the substrate strands would be cleaved in the presence of the Zn2+ and Cu2+ target, resulting in disassociation of the shorter DNA fragments containing fluorophores, which produce fluorescence signals correlated with the location and concentration of the Zn2+ and Cu2+. The nanoprobe exhibits high specificity, nuclease stability, and good biocompatibility. Moreover, the nanoprobe can simultaneously monitor the cellular Zn2+ and Cu2+ with an on-site manner, providing the information on localization and concentration of targets, which is significant to further research the Zn2+- and Cu2+-relative cellular events and biological process. The proposed method has shown great potential in the detection of multiple metal ions in living cells, which may help us to better understand the function of metal ions in the fields of biochemistry, molecular biology, and cellular toxicology.