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  1. Article ; Online: pH-regulated ionic current rectification in conical nanopores functionalized with polyelectrolyte brushes.

    Zeng, Zhenping / Ai, Ye / Qian, Shizhi

    Physical chemistry chemical physics : PCCP

    2014  Volume 16, Issue 6, Page(s) 2465–2474

    Abstract: Mimicking biological ion channels capable of pH-regulated ionic transport, synthetic nanopores functionalized with pH-tunable polyelectrolyte (PE) brushes have been considered as versatile tools for active transport control of ions, fluids, and ... ...

    Abstract Mimicking biological ion channels capable of pH-regulated ionic transport, synthetic nanopores functionalized with pH-tunable polyelectrolyte (PE) brushes have been considered as versatile tools for active transport control of ions, fluids, and bioparticles on the nanoscale. The ionic current rectification (ICR) phenomenon through a conical nanopore functionalized with PE brushes whose charge highly depends upon the local solution properties (i.e., pH and background salt concentration) is studied theoretically for the first time. The results show that the rectification magnitude, as well as the preferential rectification direction, is sensitive to the pH stimulus. The bulk concentration of the background salt can also significantly influence the charge of the PE brushes and accordingly affect the ICR phenomenon. The obtained results provide an insightful understanding of the pH-regulated ICR and guidelines for designing nanopores functionalized with PE brushes for pH-tunable applications.
    MeSH term(s) Computer Simulation ; Electrolytes/chemistry ; Hydrogen-Ion Concentration ; Ion Transport ; Ions/chemistry ; Models, Chemical ; Nanopores/ultrastructure
    Chemical Substances Electrolytes ; Ions
    Language English
    Publishing date 2014-02-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c3cp54097a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Direct numerical simulation of AC dielectrophoretic particle-particle interactive motions.

    Ai, Ye / Zeng, Zhenping / Qian, Shizhi

    Journal of colloid and interface science

    2014  Volume 417, Page(s) 72–79

    Abstract: Under an AC electric field, individual particles in close proximity induce spatially non-uniform electric field around each other, accordingly resulting in mutual dielectrophoretic (DEP) forces on these particles. The resulting attractive DEP particle- ... ...

    Abstract Under an AC electric field, individual particles in close proximity induce spatially non-uniform electric field around each other, accordingly resulting in mutual dielectrophoretic (DEP) forces on these particles. The resulting attractive DEP particle-particle interaction could assemble individual colloidal particles or biological cells into regular patterns, which has become a promising bottom-up fabrication technique for bio-composite materials and microscopic functional structures. In this study, we developed a transient multiphysics model under the thin electric double layer (EDL) assumption, in which the fluid flow field, AC electric field and motion of finite-size particles are simultaneously solved using an Arbitrary Lagrangian-Eulerian (ALE) numerical approach. Numerical simulations show that negative DEP particle-particle interaction always tends to attract particles and form a chain parallel to the applied electric field. Particles usually accelerate at the first stage of the attractive motion due to an increase in the DEP interactive force, however, decelerate until stationary at the second stage due to a faster increase in the repulsive hydrodynamic force. Identical particles move at the same speed during the interactive motion. In contrast, smaller particles move faster than bigger particles during the attractive motion. The developed model explains the basic mechanism of AC DEP-based particle assembly technique and provides a versatile tool to design microfluidic devices for AC DEP-based particle or cell manipulation.
    Language English
    Publishing date 2014-03-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2013.11.034
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 71/707: Show issues

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  3. Article ; Online: Ion transport and selectivity in biomimetic nanopores with pH-tunable zwitterionic polyelectrolyte brushes.

    Zeng, Zhenping / Yeh, Li-Hsien / Zhang, Mingkan / Qian, Shizhi

    Nanoscale

    2015  Volume 7, Issue 40, Page(s) 17020–17029

    Abstract: Inspired by nature, functionalized nanopores with biomimetic structures have attracted growing interests in using them as novel platforms for applications of regulating ion and nanoparticle transport. To improve these emerging applications, we study ... ...

    Abstract Inspired by nature, functionalized nanopores with biomimetic structures have attracted growing interests in using them as novel platforms for applications of regulating ion and nanoparticle transport. To improve these emerging applications, we study theoretically for the first time the ion transport and selectivity in short nanopores functionalized with pH tunable, zwitterionic polyelectrolyte (PE) brushes. In addition to background salt ions, the study takes into account the presence of H(+) and OH(-) ions along with the chemistry reactions between functional groups on PE chains and protons. Due to ion concentration polarization, the charge density of PE layers is not homogeneously distributed and depends significantly on the background salt concentration, pH, grafting density of PE chains, and applied voltage bias, thereby resulting in many interesting and unexpected ion transport phenomena in the nanopore. For example, the ion selectivity of the biomimetic nanopore can be regulated from anion-selective (cation-selective) to cation-selective (anion-selective) by diminishing (raising) the solution pH when a sufficiently small grafting density of PE chains, large voltage bias, and low background salt concentration are applied.
    MeSH term(s) Biomimetic Materials/chemistry ; Hydrogen-Ion Concentration ; Ion Transport ; Nanopores
    Language English
    Publishing date 2015-10-28
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/c5nr05828g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Tuning ion transport and selectivity by a salt gradient in a charged nanopore.

    Yeh, Li-Hsien / Hughes, Christopher / Zeng, Zhenping / Qian, Shizhi

    Analytical chemistry

    2014  Volume 86, Issue 5, Page(s) 2681–2686

    Abstract: Inspired by ion channels in biological cells where the intracellular and extracellular ionic concentrations are typically different, a salt concentration gradient through a charged nanopore is proposed to actively regulate its ion transport and ... ...

    Abstract Inspired by ion channels in biological cells where the intracellular and extracellular ionic concentrations are typically different, a salt concentration gradient through a charged nanopore is proposed to actively regulate its ion transport and selectivity. Results obtained show that, in addition to the ion current rectification phenomenon, a reversed ion selectivity of the nanopore occurs when the concentration gradient is sufficiently large. In addition, if the directions of the applied concentration gradient and electric field are identical, a reversed magnified electric field occurs near the cathode side of the nanopore. This induced field can be used to enhance the capture rate of biomolecules and is therefore capable of improving the performance of single biomolecule sensing using nanopores.
    MeSH term(s) Ion Transport ; Models, Theoretical ; Nanopores ; Salts/chemistry
    Chemical Substances Salts
    Language English
    Publishing date 2014-03-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1508-8
    ISSN 1520-6882 ; 0003-2700
    ISSN (online) 1520-6882
    ISSN 0003-2700
    DOI 10.1021/ac4040136
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 4033: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Article: Tuning Ion Transport and Selectivity by a Salt Gradient in a Charged Nanopore

    Yeh, Li-Hsien / Hughes Christopher / Qian Shizhi / Zeng Zhenping

    Analytical chemistry. 2014 Mar. 04, v. 86, no. 5

    2014  

    Abstract: Inspired by ion channels in biological cells where the intracellular and extracellular ionic concentrations are typically different, a salt concentration gradient through a charged nanopore is proposed to actively regulate its ion transport and ... ...

    Abstract Inspired by ion channels in biological cells where the intracellular and extracellular ionic concentrations are typically different, a salt concentration gradient through a charged nanopore is proposed to actively regulate its ion transport and selectivity. Results obtained show that, in addition to the ion current rectification phenomenon, a reversed ion selectivity of the nanopore occurs when the concentration gradient is sufficiently large. In addition, if the directions of the applied concentration gradient and electric field are identical, a reversed magnified electric field occurs near the cathode side of the nanopore. This induced field can be used to enhance the capture rate of biomolecules and is therefore capable of improving the performance of single biomolecule sensing using nanopores.
    Keywords electric field ; electrodes ; ion channels ; nanopores ; salt concentration
    Language English
    Dates of publication 2014-0304
    Size p. 2681-2686.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 1508-8
    ISSN 1520-6882 ; 0003-2700
    ISSN (online) 1520-6882
    ISSN 0003-2700
    DOI 10.1021%2Fac4040136
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 4' 52/94: Show issues
    Z 2.9: Show issues

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