DNAzyme-driven bipedal DNA walker and catalytic hairpin assembly multistage signal amplified electrochemical biosensor based on porous AuNPs@Zr-MOF for detection of Pb.

As a highly toxic and refractory heavy metal contaminant, Pb seriously endangers human health. The problems of low sensitivity and high cost of signal labeling widely exist in common electrochemical biosensors. Herein, a Pb electrochemical biosensor was constructed using a DNAzyme-driven bipedal DNA Walker and catalytic hairpin assembly as the multistage signal amplification strategy. Compared with Zr-MOF, AuNPs@Zr-MOF has a larger porosity and specific surface area, which can effectively load MB to amplify the current signal. Pb can trigger a dual signal amplification reaction to gradually accumulate the signal of methylene blue/gold nanoparticle @ zirconium-based metal organic frameworks (MB/AuNPs@Zr-MOF) on the electrode. The ingeniously designed sensing strategy realized the analysis of Pb with a wide linear range from 0.05 to 1000 nmol/L and a lower limit of detection (LOD) of 4.65 pmol/L. In addition, the sensor has strong anti-interference ability and can accurately detect Pb in various food samples.