Homogeneous Chemiluminescent Determination of Mercury(II) Using a Peroxidase-Mimicking DNAzyme Assay

Environmental pollution in manufacturing sectors is often accompanied by the release of diverse forms of pollutants including heavy metals. Mercury is one of the most toxic heavy metals. Here, we describe a homogeneous chemiluminescent method for Hg²⁺ detection based on allosteric activation of peroxidase-mimicking DNAzyme and formation of Hg²⁺-thymine bonds in DNA duplex with T–T mismatches in the presence of mercury. The formation of such duplex increased the activity of peroxidase-mimicking DNAzyme. The analysis conditions and structures of probes were optimized. Under the favorable conditions, the limit of detection and a linear range of the assay were 12 and 12–600?nM, respectively. The values of coefficient of variation measured within the working range varied from 0.7 to 3.0%. The study of cross-reactivity of Hg²⁺, Ag⁺, Pb²⁺, Ca²⁺, Zn²⁺, Bi³⁺, Ni²⁺, Co²⁺, Ba²⁺, Mn²⁺, Cd²⁺, Mg²⁺, and Cr³⁺ showed that only mercury in concentration nanoscale activates peroxidase-mimicking DNAzyme that indicates high specificity of the developed Hg²⁺ assay. Thus, an easy-to-use, specific, rapid, and sensitive method for Hg²⁺ detection was developed.