Structural and positional impact on DNAzyme-based electrochemical sensors for metal ions.

The rapid, accurate and convenient detection of heavy metal is very important to public health. Here, we developed a DNAzyme-based electrochemical sensor for Pb2+. A DNAzyme-including and Pb2+ active probe was anchored to the biosensing interface, based on the well-defined self-assembled, three-dimensional DNA nanostructure. The results indicate that the detection performance depends on the change of distances between the methylene blue and the electrode surface. The limit of detection (LOD) could reach the concentration of 0.01 μM Pb2+, and the signal change shows semi-logarithmic relationship with the concentration of Pb2+ from 0.01 μM to 100 μM. The biosensor also presents good stability and specificity to detect Pb2+ in tap or river water. This method not only provides promising approach for improving the performance of tetrahedra in detecting Pb2+, but helps deepen the understanding of tetrahedral structure design and how the position of electroactive groups affects the performance of electrochemical sensing.