A Novel Impedimetric Biosensor for Detection of Lead (II) with Low-cost Interdigitated Electrodes Made on PCB

A novel, low-cost, label-free impedance biosensor based on gold interdigitated electrodes (GIE) was developed for detection of lead. This sensor was developed by immobilizing GR-5 DNAzymes onto the GIE surface through Au-S bonding. In the presence of lead, the substrate strand was cleaved into two parts at the RNA site (rA) and caused changes in the interfacial properties of the GIE, resulting in a corresponding decrease in the impedance magnitude. Thus, by measuring the decrease, the concentration of lead ion can be determined. And coupled the GIE with GR-5 DNAzyme recognition, our proposed lead biosensor exhibited a high sensitivity with a detection limit of 6.61 nM, which is much lower than the 72 nM defined as the maximum contamination level (MCL) of lead ions in drinking water by The United States Environmental Protection Agency (EPA), at the same time, with a linear range from 10–100 nM and a prominent selectivity against other heavy metal ions. What’s more, different from the traditional way, the GIE are made on printed circuit board (PCB), this makes the biosensor has the advantages of simplicity, low cost and easy mass production, and it can easily be widely used.