Simple, one-step and amplified Hg2+ detection strategy based on DNAzyme motor

A simple, one-step and amplified Hg2+ detection strategy based on DNAzyme motor was described here. Fluorophore labeled DNA probes and long arm DNA are immobilized on the AuNPs by Au-S bond. The fluorescent signal of DNA probe is significantly quenched by AuNPs. In the presence of Hg2+, thymine-Hg2+-thymine (T-Hg2+-T) interaction can causes the duplex structure of split E-DNA and then form an entire E-DNA. Then the E-DNA can bind with fluorophore labeled DNA to form Mg2+-dependent DNAzyme structure. With the assistance of Mg2+, the fluorophore labeled DNA can be circularly cleaved by DNAzyme and then leave from the AuNPs surface. The recycling cleavage and binding processes caused processive moving of E-DNA on AuNPs surface and significant fluorescent signal recovery. A good linear relationship was obtained between fluorescence intensity and Hg2+ concentration in the range from 0.1 nM to 5 nM. The limit of detection was calculated to be 30 pM. This strategy was successfully used for detection of Hg2+ in Chinese herbs (Atractylodes macrocephala Koidz), showing a promising practical application future.