Probe-Based Nanopore Sensing for Environmental Monitoring

Nanopore sensing was invented in the mid-1990s, and is a label-free and amplification-free technique for measuring single molecules. Nanopore sensor works by monitoring the ionic current modulations as an analyte enters a nanoscale-sized cavity at a fixed applied potential. Over the past 20 years, nanopore technique has been successfully utilized for a wide variety of applications, including biosensing, sequencing DNA molecules, studying covalent and non-covalent bonding interactions, investigating biomolecular folding and unfolding, environmental monitoring, and so on.

Peptides possess a range of potential donor atoms, and are very effective ligands for a variety of metal ions with high specificities. Based on the difference in the number of peptide events, the mean residence time and/or the blockage amplitude in the absence and presence of metal ions, nanomolar concentration of metallic ions could be detected in minutes.

Herein, I will highlight my recent research efforts to investigate different peptides as chelating agents to detect heavy metal ions in drinking water. In addition, the selectivity of this technique is examined by investigating the effects of main group metal ions such as Ca²⁺, Mg²⁺ and a wide variety of other heavy metal ions having similar chemical properties to the target analytes such as Zn²⁺, Pb²⁺ Cd²⁺, Hg^2+, Co²⁺, Cu²⁺, Ni²⁺, UO₂²⁺, Th⁴⁺ on the peptide ligand translocation in the nanopore. Lastly, to demonstrate the potential application of nanopore sensors in real-world sample analysis, several simulated contaminated water samples would be constructed by spiking certain amounts (ranging from 10 nM to 1 µM) of metal ions in tap water, lake water, and bottled spring water. These samples would be analyzed by the developed nanopore sensor.