Abstract: A novel fluorescent probe for Pb²⁺ was obtained, in which the quencher modified 17E DNAzyme and the fluorophore-modified substrate strand were connected through 6 adenine deoxynucleotides. Due to the intramolecular hybridization between 17E DNAzyme and the substrate strand, the quencher was closed to the fluorophore and it resulted in fluorescence quenching. In the presence of Pb²⁺, the substrate strand was cleaved under the catalysis of enzyme strand, and the fluorophore-modified fragment was released, which resulted in the increase of fluorescence. Pb²⁺ could be rapidly detected at room temperature based on this principle, and the limits of detection were 10 nmol/L. For divalent metal ions, such as Zn²⁺, Mn²⁺, Co²⁺, Cd²⁺, Cu²⁺, Mg²⁺ and Ni²⁺, only Zn²⁺, Mn²⁺ and Cd²⁺ showed a slight increase of fluorescence intensity while all the other metal ions gave approximately background intensity. It is demonstrated that the novel fluorescent probe has a good selectivity to Pb²⁺.

Key words: 17E DNAzyme, Lead, Fluorescence