The Role of Nanopore Geometry for the Rectification of Ionic Currents

Kubeil, Clemens; Bund, Andreas

doi:10.1021/jp111377h

Cited by 107 publications

(178 citation statements)

References 39 publications

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“…Similar simulations have previously been done for nanopores 36,37 and for nanopipettes. 31 The geometry used for the simulations is shown in Supporting Fig.…”

Section: Finite Element Simulationsmentioning

confidence: 58%

“…3). Even if the concentration of ions close to the tip of the nanopipette is changing under conditions of ion rectification, the concentration far from the tip should be independent of the sign of the applied voltage 36,37 and the electric field in that region can be estimated by I/(A×K), where A is the cross-sectional area of the nanopipette in the studied region.…”

Section: Resultsmentioning

confidence: 99%

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On-Demand Delivery of Single DNA Molecules Using Nanopipets

et al. 2015

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Understanding the behavioral properties of single molecules or larger scale populations interacting with single molecules is currently a hotly pursued topic in nanotechnology. This arises from the potential such techniques have in relation to applications such as targeted drug delivery, early stage detection of disease, and drug screening. Although label and label-free single molecule detection strategies have existed for a number of years, currently lacking are efficient methods for the controllable delivery of single molecules in aqueous environments. In this article we show both experimentally and from simulations that nanopipets in conjunction with asymmetric voltage pulses can be used for label-free detection and delivery of single molecules through the tip of a nanopipet with "on-demand" timing resolution. This was demonstrated by controllable delivery of 5 kbp and 10 kbp DNA molecules from solutions with concentrations as low as 3 pM.

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“…Similar simulations have previously been done for nanopores 36,37 and for nanopipettes. 31 The geometry used for the simulations is shown in Supporting Fig.…”

Section: Finite Element Simulationsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

On-Demand Delivery of Single DNA Molecules Using Nanopipets

et al. 2015

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“…[38][39][40] Due to the conical shape of the nanopore, when a negative potential is applied to the interior of the nanopore relative to the exterior, positively charged K + ions move from the bulk solution towards the interior of the pore while negatively charged Cl -ions move in the opposite direction. However, since the pore wall is negatively charged, K + accumulate at the pore orifice while the transit of Clions is partially blocked, resulting in an accumulation of both ions and a conductance higher than the bulk value.…”

Section: Resultsmentioning

confidence: 99%

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 11 The use of the Nernst-Planck (NP) equation to describe ion fluxes is reasonable when the applied pressure is zero and the electro-osmotic flow is negligible, conditions that match those used in this experiment. [48][49][50][51] Solving the coupled Poisson and NernstPlanck equations as a function of temperature requires that D i for K + and Cl -are known as a function of temperature. We used the Stokes-Einstein relationship to estimate the ion diffusion coefficients:…”

Section: Finite Element Simulationsmentioning

confidence: 99%

Effect of the Electric Double Layer on the Activation Energy of Ion Transport in Conical Nanopores

et al. 2015

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Measured apparent activation energies, E A , of ion transport (K + and Cl -) in conical glass nanopores are reported as a function of applied voltage (-0.5 to 0.5 V), pore size (20 -2000 nm) and electrolyte concentration (0.1 -50 mM). E A values for transport within an electrically charged conical glass nanopore differ from the bulk values due to the voltage and temperature-dependent distribution of the ions within the double layer. Remarkably, nanopores that display ion current rectification also display a large increase in E A under accumulation mode conditions (at applied negative voltages versus an external ground) and a large decrease in E A under depletion mode conditions (at positive voltages). Finite element simulations based on the Poisson-Nernst-Planck model semi-quantitatively predict the measured temperature-dependent conductivity and dependence of E A on applied voltage. The results highlight the relationships between the distribution of ions with the nanopore, ionic current, and E A , and their dependencies on pore size, temperature, ion concentration, and applied voltage.

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“…43,45,60,62 Analytical approaches, such as utilizing equation 3 or similar equations for calculating the nanopipette radius or resistive properties, often at a fixed applied bias, 55,56 may evidently become inaccurate under these conditions, as the surface charge of the nanopipette is not generally considered. While there has been much work on the study and simulation of the ICR phenomena at nanopipettes in low ionic strength, 60,62,63 quantification of the nanopipette surface charge and understanding the nanopipette current response is a difficult task owing to a lack of more complete tip characterization methods.…”

Section: Evaluation Of Existing Methods For Nanopipette Characterizationmentioning

confidence: 99%

Characterization of Nanopipettes

et al. 2016

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Nanopipettes are widely used in electrochemical and analytical techniques as tools for sizing, sequencing, sensing, delivery and imaging. For all of these applications, the response of a nanopipette is strongly affected by its geometry and surface chemistry. As the size of nanopipettes becomes smaller, precise geometric characterization is increasingly important, especially if nanopipette probes are to be used for quantitative studies and analysis. This contribution highlights the combination of data from voltage-scanning ion conductivity experiments, transmission electron microscopy (TEM) and finite element method (FEM) simulations to fully characterize nanopipette geometry and surface charge characteristics, with an accuracy not achievable using existing approaches. Indeed, it is shown that presently used methods for nanopipette characterization can lead to highly erroneous information on nanopipettes. The new approach to characterization further facilitates high-level quantification of the behavior of nanopipettes in electrochemical systems, as demonstrated herein for a scanning ion conductance microscope (SICM) setup.

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The Role of Nanopore Geometry for the Rectification of Ionic Currents

Cited by 107 publications

References 39 publications

On-Demand Delivery of Single DNA Molecules Using Nanopipets

On-Demand Delivery of Single DNA Molecules Using Nanopipets

Effect of the Electric Double Layer on the Activation Energy of Ion Transport in Conical Nanopores

Characterization of Nanopipettes

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