Wireless Bipolar Nanopore Electrode for Single Small Molecule Detection.

Solid-state nanopore-based techniques have become a promising strategy for diverse single molecule detections. Owing to the challenge in well and rapid fabrication of solid-state nanopores with the diameter less than 2 nm, small molecule detection is hard to be addressed by existing label-free nanopore methods. In this work, we for the first time propose a metal-coated wireless nanopore electrode (WNE) which offers a novel and generally accessible detection method for analyzing small molecules and ions at the single molecule/ion level. Here, a silver-coated WNE is developed as a proof-of-principle model which achieves the detection the self-generated H ₂ , the smallest known molecule, and Ag ⁺ at single molecule/ion level by monitoring the enhanced ionic signatures. Under a bias potential of -800 mV, the WNE could accomplish the distinction of as low as 14 H ₂ molecules and 28 Ag ⁺ from one spike signal. The finite element simulation is introduced to suggest that the generation of H ₂ at the orifice of the WNE results in the enhanced spike of ionic current. As a proof-of-concept experiment, the WNE is further utilized to directly detect Hg ²⁺ from 100 pM to 100 nM by monitoring the frequency of the spike signals. This novel nanoelectrode provides a brand new label-free, ultrasensitive, and simple detection mechanism for various small molecules/ions detection, especially for redox analytes.