Lead ion (Pb²⁺) is a common environmental contaminant, which causes serious bioaccumulation and toxicity in human body. In this work, we developed a novel Pb²⁺ electrochemical biosensor using the specific DNAzyme on a DNA tetrahedron probe, in the presence of Pb²⁺, the substrate strand was cleaved into two parts and released a “G-rich” oligo which subsequently formed a G-quadruplex/hemin complex, generating a detectable catalysis current signal with the assistant of H₂O₂. The 3-D DNA tetrahedron regulated the density and orientation of the probe and thus improved the DNAzyme reaction, and facilitated the complex DNA conformational change in the confined space of the interface on the electrode surface, Finally, the LOD of our biosensor was proved to be 0.008 nM (3σ), which is 9000 times lower than the safety limit of EPA (15 μg/L or 72 nM), and 6000 times lower than IARC (10 μg/L or 48.26 nM), and more importantly, the specificity and reproducibility of the proposed biosensor was well demonstrated.

铅离子（Pb ²⁺）是一种常见的环境污染物，会导致严重的生物积累和对人体的毒性。在这项工作中，我们开发了一种新颖的Pb ²⁺电化学生物传感器，使用DNA四面体探针上的特定DNAzyme，在Pb ²⁺存在下，底物链被切割成两个部分，并释放出“富含G”的寡核苷酸，随后形成一个G-四链体/血红素络合物，在H ₂ O ₂的辅助下产生可检测的催化电流信号。3-D DNA四面体调节了探针的密度和方向，从而改善了DNAzyme反应，并促进了电极表面界面密闭空间中复杂的DNA构象变化，最后证明了我们的生物传感器的LOD为0.008 nM（3σ），比EPA的安全极限（15μg/ L或72 nM）低9000倍，比IARC（10μg/ L或48.26 nM）低6000倍，更重要的是，特异性并很好地证明了所提出的生物传感器的可重复性。