A 30 nm Nanopore Electrode: Facile Fabrication and Direct Insights into the Intrinsic Feature of Single Nanoparticle Collisions

Abstract

Clarifying the hidden but intrinsic feature of single nanoparticles by nanoelectrochemistry could help understand its potential for diverse applications. The uncontrolled interface and bandwidth limitation in the electrochemical measurement put the obstacle in single particle collision. Here, we demonstrate a well-defined 30 nm nanopore electrode with a rapid chemical-electrochemical fabrication method which provides a high reproducibility in both size and performance. A capacitance-based detection mechanism is demonstrated to achieve a high current resolution of 0.6 pA ±0.1 pA (RMS) and a high the temporal resolution of 0.01 ms. By utilizing this electrode, the dynamic interactions of every single particle in the mixture could be directly read during the collision process. The collision frequency is two orders of magnitude higher than previous reports, which helps reveal the hidden features of nanoparticles during the complex and multidimensional interaction processes.

Confined Nanopipette Sensing: From Single Molecules, Single Nanoparticles, to Single Cells

“…[49] To improve the sensitivity of nanopipettes in singleparticle discriminations,anew capacitive feedback response (CFR) mechanism was presented, which enabled the collisions of single nanoparticles to be observed (Figure 2d). [50] TheC FR effect is based on ac onfined nanopore electrode which was fabricated by the rapid chemical-electrochemical method. As aconsequence of the highly uniform structure of the nanopore tip,t he confined nanopore electrode leads to inconsistencyi nt he bandwidth and noise.I ta chieves ah igh current resolution of (0.6 AE 0.1) pA (root-mean square;RMS) with ah igh temporal resolution of 0.01 ms.A sar esult, the collision frequencyofthe gold nanoparticles increased at least two orders of magnitude compared to at raditional ultramicroelectrode.B yu tilizing this electrode,t he dynamic interactions of every particle in the mixture could be directly read during the collision process.I na ddition, the conductive materials coated on the nanopipette could act as an electrode surface,w hich could be applied for the electrochemical sensing of single nanoparticles.…”

Nanopore‐Based Confined Spaces for Single‐Molecular Analysis

“…A glass‐capillary‐based nanoelectrode has achieved high sensitivity, owing to the confined nanospace in the orifices. The glass capillary was fabricated into a tip (diameter: 30 nm) and the inside was deposited with gold, thereby creating a so‐called “confined nanopore electrode” (CNE) . This CNE was powerful enough to distinguish ionic migrations of 0.6 pA and a temporal resolution of 0.01 ms, for discriminating between single‐particle collisions and even gas bubbles on the nanoscale…”

Nanopore Electrochemistry: A Nexus for Molecular Control of Electron Transfer Reactions

“… 74 − 76 Since these early reports, it has become possible to sequester a few nanoparticles, or even one. 77 , 78 Recently, Long et al reported an innovative nanopore bipolar electrode to control the dynamic self-assembly of gold nanoparticles, 79 Figure 3 c. Similarly, White and co-workers proposed a super-resolution imaging method to map the trajectories of fluorescent nanoparticles around the tip of a nanopipette, 80 Figure 3 d. These are just a few examples illustrating the broad interest in single entity electrochemistry; readers may refer to recent comprehensive reviews for additional details. 81 − 84 …”