Next‐Generation Nanopore Sensors Based on Conductive Pulse Sensing for Enhanced Detection of Nanoparticles

Abstract

Nanopore sensing has been successfully used to characterize biological molecules with single‐molecule resolution based on the resistive pulse sensing approach. However, its use in nanoparticle characterization has been constrained by the need to tailor the nanopore aperture size to the size of the analyte, precluding the analysis of heterogeneous samples. Additionally, nanopore sensors often require the use of high salt concentrations to improve the signal‐to‐noise ratio, which further limits their ability to study a wide range of nanoparticles that are unstable at high ionic strength. Here, a new paradigm in nanopore research that takes advantage of a polymer electrolyte system to comprise a conductive pulse sensing approach is presented. A finite element model is developed to explain the conductive pulse signals observed and compare these results with experiments. This system enables the analytical characterization of heterogeneous nanoparticle mixtures at low ionic strength . Furthermore, the wide applicability of the method is demonstrated by characterizing metallic nanospheres of varied sizes, plasmonic nanostars with various degrees of branching, and protein‐based spherical nucleic acids with different oligonucleotide loadings. This system will complement the toolbox of nanomaterials characterization techniques to enable real‐time optimization workflow for engineering a wide range of nanomaterials.

Solid‐State Glass Nanopipettes: Functionalization and Applications

“…Copyright 2020, American Chemical Society. b) Scheme of enhanced nanoparticle detection in a polymer electrolyte bath [93] . Reproduced with permission.…”

“…[92] Recently, Confederat and coworkers reported a novel strategy using a polymer electrolyte system to comprise a conductive pulse sensing approach (Figure 8b). [93] This system enables the analytical characterization of heterogeneous nanoparticle mixtures at low ionic strength, which avoids the disturbance of high concentration of electrolyte and overcomes the need to tailor the nanopore aperture size to the size of the analyte. In addition, nucleic acid tests are essential for clinical molecular diagnosis, especially during the global spread of novel coronavirus (SARS-CoV-2).…”

“…b) Scheme of enhanced nanoparticle detection in a polymer electrolyte bath. [93] Reproduced with permission. Copyright 2023, Wiley-VCH.…”

Single molecule delivery into living cells

“…Nanopipettes have been used hitherto for quantitative detection and characterisation of biological macromolecules in vitro with single molecule resolution, including globular proteins, amyloid fibrils, nucleic acids, ribosomes and nanostructures [32][33][34][35][36][37][38][39] . To demonstrate that nanopipettes can also be used for the quantitative delivery of macromolecules at single molecule resolution into cells and that this results in a demonstrable phenotypic effect, we used the nanoinjection platform to deliver a DNA plasmid into the nucleus of the human cervical epithelial HeLa cell line.…”

“…The translocation of a single macromolecule through the pore at the tip of a nanopipette results in a detectable alteration in the measured ionic current, which can be used to characterise and quantify the number of molecules that pass through the nanopore [32][33][34][35][36][37][38][39] . In recent work, we have shown that the detection of nucleic acids and proteins is enhanced by their translocation into a polymer-electrolyte bath containing poly(ethylene) glycol (PEG) 33,36 , and have shown that this arises from a combination of unique ion transport behaviour and the interaction between the translocating molecule and the polymer-electrolyte interface 38,39 . Inspired by these observations, we here describe the development of a nanoinjection platform in which nanopipettes are used to perform the quantitative delivery of biological macromolecules into the highly crowded interior of mammalian cells that induce different cellular responses.…”