Ultrasensitive photoelectrochemical sensing of Pb2 + based on allosteric transition of G-Quadruplex DNAzyme

•Photoelectrochemical (PEC) Pb2 + sensing was achieved firstly.•G-quadruplex-based DNAzyme and biocatalytic precipitation were coupled.•Amplified ultrasensitive PEC detection of Pb2 + was realized.•It opened a different horizon for PEC ions sensing.

A sensitive photoelectrochemical (PEC) approach for Pb2 + sensing was achieved firstly with the coupling of G-quadruplex-based DNAzyme and biocatalytic precipitation (BCP) on a CdS quantum dots electrode. Pb2 + can induce the conformational change of K+-stabilized G-quadruplex-based DNAzyme, leading to the decrease of the catalytic activity to H2O2-mediated 4-chloro-1-naphthol oxidation (BCP reaction). From the respective BCP reaction that monitors the event of DNAzyme deactivation, a novel PEC Pb2 + sensor could be realized with a detection limit of 1.0 × 10− 8 M.