# Non-Faradaic Impedimetric Detection of Heavy Metal Ions via a Hybrid Nanoparticle-DNAzyme Biosensor

## TL;DR

A new biosensor using nanoparticles and DNAzymes detects toxic heavy metals in water with high sensitivity.

## Contribution

First use of non-Faradaic EIS with nanoparticle-DNAzyme hybrids for detecting Pb2+ and Cr3+.

## Key findings

- The sensor detects Pb2+ and Cr3+ below their maximum permitted levels in tap water.
- DNAzyme structure disassembles in the presence of target heavy metal ions.
- Non-Faradaic EIS technique shows promise for heavy metal detection with nanomaterials.

## Abstract

Due to rapid industrialization, novel water-quality monitoring techniques for the detection of highly toxic and hazardous heavy metal ions are essential. Herein, a hybrid noble nanoparticle/DNAzyme electrochemical biosensor is proposed for the simultaneous and label-free detection of Pb2+ and Cr3+ in aqueous solutions. The sensor is based on the combination of a two-dimensional naked-platinum nanoparticle film and DNAzymes, whose double-helix configuration disassembles into smaller fragments in the presence of target-specific heavy metal ions. The electrochemical behavior of the fabricated sensor was investigated with non-faradaic electrochemical impedance spectroscopy (EIS), resulting in the successful detection of Pb2+ and Cr3+ well below their maximum permitted levels in tap water. So far, there has been no report on the successful detection of heavy metal ions utilizing the non-faradaic electrochemical impedance spectroscopy technique based on advanced nanomaterials paired with DNAzymes. This is also one of the few reports on the successful detection of chromium (III) via a sensor incorporating DNAzymes.