Conical Nanopore Membranes: Controlling the Nanopore Shape

Harrell, C. Chad; Siwy, Zuzanna S.; Martin, Charles R.

doi:10.1002/smll.200500196

Cited by 147 publications

(151 citation statements)

References 31 publications

(58 reference statements)

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“…10,11 Polymer samples containing single asymmetric nanopores and multipore arrays obtained by track-etching 12 are of particular interest because they mimic some of the transport properties of biological ion channels. [13][14][15][16][17][18][19] Recent advances concerning the fabrication processes and the tailoring of the surface properties have permitted to control the pore geometry [20][21][22][23] and the response to external stimuli such as voltage, 24,25 temperature, 26,27 pH [28][29][30] or the presence of a given analyte in the pore solution. [31][32][33][34] These features have allowed the fabrication of nanofluidic devices [35][36][37][38] with potential applications in sensing, 34,39,40 energy harvesting 41,42 and information processing.…”

Section: Introductionmentioning

confidence: 99%

Nernst-Planck model of photo-triggered, pH–tunable ionic transport through nanopores functionalized with “caged” lysine chains

Nasir

Ramı́rez

Ali

et al. 2013

The Journal of Chemical Physics

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Nasir, S.; Ramirez Hoyos, P.; Ali, M.; Ahmed, I.; Fruk, L.; Mafé, S.; Ensinger, W. (2013). Nernst-Planck model of photo-triggered, pH-tunable ionic transport through nanopores functionalized with "caged" lysine chains. Journal of Chemical Physics. 138(3):034709-1-034709-11. doi:10.1063/1.4775811. Author to whom correspondence should be addressed. Electronic mail: m.ali@gsi.de AbstractWe describe the fabrication of asymmetric nanopores sensitive to ultraviolet (UV) light and give a detailed account of the divalent ionic transport through these pores using a theoretical model based on the Nernst-Planck equations. The pore surface is decorated with lysine chains having pH-sensitive (amine and carboxylic acid) moieties that are caged with photo-labile 4,5-dimethoxy-2-nitrobenzyl (NVOC) groups. The uncharged hydrophobic NVOC groups are removed using UV irradiation, leading to the generation of hydrophilic "uncaged" amphoteric groups on the pore surface. We demonstrate experimentally that polymer membranes containing single pore and arrays of asymmetric nanopores can be employed for the pH-controlled transport of ionic and molecular analytes. Comparison between theory and experiment allows for understanding the individual properties of the 2 phototriggered nanopores and provides also useful clues for the design and fabrication of multipore membranes to be used in practical applications.

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Section: Introductionmentioning

confidence: 99%

Nernst-Planck model of photo-triggered, pH–tunable ionic transport through nanopores functionalized with “caged” lysine chains

Nasir

Ramı́rez

Ali

et al. 2013

The Journal of Chemical Physics

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“…Depending on the energy regime of the ions and the type of material being bombarded, the shape of the impact features and the underlying mechanisms of formation may differ [9,10]. As the energy deposited by swift ions of equal kinetic energy, but different charge-states may vary substantially close to the surface, a detailed knowledge of charge-state dependent effects is of great importance for ion-beam based techniques of materials structuring (such as ion-track etching), particularly considering the new demands for smaller pattern sizes and the use of thinner layers [11]. Our results give direct evidence for a strong dependence of the surface modifications introduced by single fast ions on their charge state.…”

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confidence: 99%

Direct Evidence for Projectile Charge-State Dependent Crater Formation Due to Fast Ions

et al. 2008

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We report on craters formed by individual 3 MeV=u Au q ini þ ions of selected incident charge states q ini penetrating thin layers of poly(methyl methacrylate). Holes and raised regions are formed around the region of the impact, with sizes that depend strongly and differently on q ini . Variation of q ini , of the film thickness and of the angle of incidence allows us to extract information about the depth of origin contributing to different crater features. DOI: 10.1103/PhysRevLett.101.167601 PACS numbers: 79.20.Rf, 61.80.Jh, 61.82.Pv, 81.16.Rf Energetic atomic [1-3], molecular or cluster ions [4] impacting solids may leave tiny holes at the surface often surrounded by a raised region of displaced material. The observed surface morphology [1][2][3][4] is similar to what is found in ablation craters produced by an intense laser pulse [5,6], in macroscopic craters produced by meteorite impacts on planets [7], or by balls dropped into granular media [8], although their spatial scales may differ by about 17 orders of magnitude. Depending on the energy regime of the ions and the type of material being bombarded, the shape of the impact features and the underlying mechanisms of formation may differ [9,10]. As the energy deposited by swift ions of equal kinetic energy, but different charge-states may vary substantially close to the surface, a detailed knowledge of charge-state dependent effects is of great importance for ion-beam based techniques of materials structuring (such as ion-track etching), particularly considering the new demands for smaller pattern sizes and the use of thinner layers [11]. Our results give direct evidence for a strong dependence of the surface modifications introduced by single fast ions on their charge state. For track-etching procedures, this means it is possible to control the etching sensitivity at the surface and charge equilibration below the surface should yield different etched shapes, dependent on the incident charge state. Moreover, by employing a series of well-defined nonequilibrium charge states, we could derive depth information on the near-surface effects induced by single fast ion impacts.In this Letter, we focus on cratering induced by high velocity ions. At specific kinetic energies of a few MeV per nucleon, such ions transfer more than 99% of their energy to the target-electron system. A considerable fraction of the energy deposited in the track of a swift heavy ion is concentrated in a core region ( % 1 nm), where ionizations are directly produced by the ions. Fast secondary electrons spread the rest of the energy over larger distances. The exact size of such regions depend on the material and on the velocity of the ions, while the total amount of energy loss per path length, S e ¼ dE e =dx, is well understood [12]. The subsequent electron dynamics, however, is a nonlinear phenomenon and it may result in large sputter yields and cratering, due to the coupling of electronic and atomic degrees of freedom [13][14][15]. For reviews on ion-induced electronic cratering pr...

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“…[67][68][69] The fabrication process involves first bombarding a thin sheet of polymer material (polyethylene terephthalate, polyimide or polycarbonate) with a high energy beam of nuclear fission fragments or with a high energy ion beam from a MeV accelerator at normal or near normal incidence angle to the polymer substrate. The irradiated polymer membrane is then placed between two chambers of a conductivity cell and etched chemically from one side.…”

Section: Track-etch Methodsmentioning

confidence: 99%

Solid-State Nanopore Sensors for Nucleic Acid Analysis

Venkatesan

Bashir

2011

Nanopores

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Nanopore DNA analysis is an emerging technique that involves electrophoretically driving DNA molecules through a nano-scale pore in solution and monitoring the corresponding change in ionic pore current. This versatile approach permits the label-free, amplification-free analysis of charged polymers (single stranded DNA, double stranded DNA and RNA) ranging in length from single nucleotides to kilobase long genomic DNA fragments with subnanometer resolution.Recent advances in nanopores suggest that this low-cost, highly scalable technology could lend itself to the development of third generation DNA sequencing technologies, promising rapid and reliable sequencing of the human diploid genome for under $1000.Here, we report the development of versatile, nano-manufactured Al 2 O 3 solid-state nanopores and nanopore arrays for rapid, label-free, single-molecule detection and analysis of DNA and protein. This nano-scale technology has proven to be reliable, affordable, and mass producible, and allows for integration with VLSI processes. A detailed characterization of nanopore performance in terms of electrical noise, mechanical robustness and materials analysis is provided, and the functionality of this technology in experimental DNA biophysics is explored.A framework for the application of this technology to medical diagnostics and sequencing is also presented. Specifically, studies involved the detection of DNA-protein complexes, a viable strategy in screening methylation patterns in panels of genes for early cancer detection, and the creation of lipid bilayer coated nanopore sensors, useful in creating hybrid biological/solid-state nanopores for DNA sequencing applications.The concept of a gated nanopore is also presented with preliminary results. The fabrication of this novel system has been enabled by the recent discovery of graphene, a highly versatile material with remarkable electrical and mechanical properties. Direct modulation of the nanopore conductance was observed through the application of potentials to the graphene gate.These exciting results suggest this technology could potentially be useful in slowing down or trapping a DNA molecule in the pore, thereby enabling solid-state nanopore sequencing.iii

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Conical Nanopore Membranes: Controlling the Nanopore Shape

Cited by 147 publications

References 31 publications

Nernst-Planck model of photo-triggered, pH–tunable ionic transport through nanopores functionalized with “caged” lysine chains

Nernst-Planck model of photo-triggered, pH–tunable ionic transport through nanopores functionalized with “caged” lysine chains

Direct Evidence for Projectile Charge-State Dependent Crater Formation Due to Fast Ions

Solid-State Nanopore Sensors for Nucleic Acid Analysis

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