Sensitive and label-free electrochemical lead ion biosensor based on a DNAzyme triggered G-quadruplex/hemin conformation

• Published in: Biosensors & bioelectronics Vol. 115; pp. 91 - 96
• Main Authors: Wang, LeLe, Wen, Yanli, Li, Lanying, Yang, Xue, Jia, Nengqin, Li, Wen, Meng, Jiaoran, Duan, Manlei, Sun, Xiaoguang, Liu, Gang
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.09.2018
• Subjects: Biosensing Techniques; DNA - chemistry; DNA tetrahedron; DNA, Catalytic - chemistry; DNAzyme; Electrochemical biosensor; Electrochemical Techniques; G-quadruplex/hemin; G-Quadruplexes; Hemin - chemistry; Humans; Hydrogen Peroxide - chemistry; Lead - chemistry; Lead - isolation & purification; Lead ion; Limit of Detection; DNAzyme; G-quadruplex/hemin; DNA tetrahedron; Lead ion; Electrochemical biosensor
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2018.04.054

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. •We developed a novel Pb2+ electrochemical biosensor using the specific DNAzyme on a DNA tetrahedron probe.•Pb2+ triggered the DNAzyme reaction and realized the G-rich fragment to form a G-quadruplex/hemin structure.•DNA tetrahedron regulated the density and orientation of the probe and thus improved the DNA conformation switch.•the LOD of our biosensor was proved to be 0.008 nM.