1
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Chen R, Pathirathna P, Balla RJ, Kim J, Amemiya S. Nanoscale Quantitative Imaging of Single Nuclear Pore Complexes by Scanning Electrochemical Microscopy. Anal Chem 2024; 96:10765-10771. [PMID: 38904303 PMCID: PMC11223102 DOI: 10.1021/acs.analchem.4c01890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/22/2024]
Abstract
The nuclear pore complex (NPC) is a proteinaceous nanopore that solely and selectively regulates the molecular transport between the cytoplasm and nucleus of a eukaryotic cell. The ∼50 nm-diameter pore of the NPC perforates the double-membrane nuclear envelope to mediate both passive and facilitated molecular transport, thereby playing paramount biological and biomedical roles. Herein, we visualize single NPCs by scanning electrochemical microscopy (SECM). The high spatial resolution is accomplished by employing ∼25 nm-diameter ion-selective nanopipets to monitor the passive transport of tetrabutylammonium at individual NPCs. SECM images are quantitatively analyzed by employing the finite element method to confirm that this work represents the highest-resolution nanoscale SECM imaging of biological samples. Significantly, we apply the powerful imaging technique to address the long-debated origin of the central plug of the NPC. Nanoscale SECM imaging demonstrates that unplugged NPCs are more permeable to the small probe ion than are plugged NPCs. This result supports the hypothesis that the central plug is not an intrinsic transporter, but is an impermeable macromolecule, e.g., a ribonucleoprotein, trapped in the nanopore. Moreover, this result also supports the transport mechanism where the NPC is divided into the central pathway for RNA export and the peripheral pathway for protein import to efficiently mediate the bidirectional traffic.
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Affiliation(s)
- Ran Chen
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- School
of Chemistry and Chemical Engineering, Southeast
University, Nanjing 211189, China
| | - Pavithra Pathirathna
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department
of Chemistry and Chemical Engineering, Florida
Institute of Technology, Melbourne, Florida 32901, United States
| | - Ryan J. Balla
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jiyeon Kim
- Department
of Chemistry, The University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Shigeru Amemiya
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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2
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Huang SH, Parandhaman M, Farnia S, Kim J, Amemiya S. Nanoelectrochemistry at liquid/liquid interfaces for analytical, biological, and material applications. Chem Commun (Camb) 2023; 59:9575-9590. [PMID: 37458703 PMCID: PMC10416082 DOI: 10.1039/d3cc01982a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Herein, we feature our recent efforts toward the development and application of nanoelectrochemistry at liquid/liquid interfaces, which are also known as interfaces between two immiscible electrolyte solutions (ITIES). Nanopipets, nanopores, and nanoemulsions are developed to create the nanoscale ITIES for the quantitative electrochemical measurement of ion transfer, electron transfer, and molecular transport across the interface. The nanoscale ITIES serves as an electrochemical nanosensor to enable the selective detection of various ions and molecules as well as high-resolution chemical imaging based on scanning electrochemical microscopy. The powerful nanoelectroanalytical methods will be useful for biological and material applications as illustrated by in situ studies of solid-state nanopores, nuclear pore complexes, living bacteria, and advanced nanoemulsions. These studies provide unprecedented insights into the chemical reactivity of important biological and material systems even at the single nanostructure level.
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Affiliation(s)
- Siao-Han Huang
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
| | | | - Solaleh Farnia
- Department of Chemistry, University of Rhode Island, Kingston, RI, 02881, USA.
| | - Jiyeon Kim
- Department of Chemistry, University of Rhode Island, Kingston, RI, 02881, USA.
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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3
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Elangovan S, Puri SR, Madawala H, Pantano J, Pellock B, Kiesewetter MK, Kim J. Nanoscale Carbonate Ion-Selective Amperometric/Voltammetric Probes Based on Ion-Ionophore Recognition at the Organic/Water Interface: Hidden Pieces of the Puzzle in the Nanoscale Phase. Anal Chem 2023; 95:4271-4281. [PMID: 36808982 DOI: 10.1021/acs.analchem.2c02626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Here, we report on the successful demonstration and application of carbonate (CO32-) ion-selective amperometric/voltammetric nanoprobes based on facilitated ion transfer (IT) at the nanoscale interface between two immiscible electrolyte solutions. This electrochemical study reveals critical factors to govern CO32--selective nanoprobes using broadly available Simon-type ionophores forming a covalent bond with CO32-, i.e., slow dissolution of lipophilic ionophores in the organic phase, activation of hydrated ionophores, peculiar solubility of a hydrated ion-ionophore complex near the interface, and cleanness at the nanoscale interface. These factors are experimentally confirmed by nanopipet voltammetry, where a facilitated CO32- IT is studied with a nanopipet filled with an organic phase containing the trifluoroacetophenone derivative CO32-ionophore (CO32-ionophore VII) by voltammetrically and amperometrically sensing CO32- in water. Theoretical assessments of reproducible voltammetric data confirm that the dynamics of CO32- ionophore VII-facilitated ITs (FITs) follows the one-step electrochemical (E) mechanism controlled by both water-finger formation/dissociation and ion-ionophore complexation/dissociation during interfacial ITs. The yielded rate constant, k0 = 0.048 cm/s, is very similar to the reported values of other FIT reactions using ionophores forming non-covalent bonds with ions, implying that a weak binding between CO32- ion-ionophore enables us to observe FITs by fast nanopipet voltammetry regardless of the nature of bondings between the ion and ionophore. The analytical utility of CO32--selective amperometric nanoprobes is further demonstrated by measuring the CO32- concentration produced by metal-reducing bacteria Shewanella oneidensis MR-1 as a result of organic fuel oxidation in bacterial growth media in the presence of various interferents such as H2PO4-, Cl-, and SO42-.
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Affiliation(s)
- Subhashini Elangovan
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Surendra Raj Puri
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Hiranya Madawala
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Justin Pantano
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Brett Pellock
- Department of Biology, Providence College, Providence, Rhode Island 02981, United States
| | - Matthew K Kiesewetter
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Jiyeon Kim
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
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4
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Chen R, Liu S, Zhang Y. A nanoelectrode-based study of water splitting electrocatalysts. MATERIALS HORIZONS 2023; 10:52-64. [PMID: 36485037 DOI: 10.1039/d2mh01143c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The development of low-cost and efficient catalytic materials for key reactions like water splitting, CO2 reduction and N2 reduction is crucial for fulfilling the growing energy consumption demands and the pursuit of renewable and sustainable energy. Conventional electrochemical measurements at the macroscale lack the potential to characterize single catalytic entities and nanoscale surface features on the surface of a catalytic material. Recently, promising results have been obtained using nanoelectrodes as ultra-small platforms for the study of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on innovative catalytic materials at the nanoscale. In this minireview, we summarize the recent progress in the nanoelectrode-based studies on the HER and OER on various nanostructured catalytic materials. These electrocatalysts can be generally categorized into two groups: 0-dimensional (0D) single atom/molecule/cluster/nanoparticles and 2-dimensional (2D) nanomaterials. Controlled growth as well as the electrochemical characterization of single isolated atoms, molecules, clusters and nanoparticles has been achieved on nanoelectrodes. Moreover, nanoelectrodes greatly enhanced the spatial resolution of scanning probe techniques, which enable studies at the surface features of 2D nanomaterials, including surface defects, edges and nanofacets at the boundary of a phase. Nanoelectrode-based studies on the catalytic materials can provide new insights into the reaction mechanisms and catalytic properties, which will facilitate the pursuit of sustainable energy and help to solve CO2 release issues.
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Affiliation(s)
- Ran Chen
- Jiangsu Province Key Laboratory of Critical Care Medicine, Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-Medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, China.
| | - Songqin Liu
- Jiangsu Province Key Laboratory of Critical Care Medicine, Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-Medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, China.
| | - Yuanjian Zhang
- Jiangsu Province Key Laboratory of Critical Care Medicine, Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-Medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, China.
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5
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Jantz DT, Balla RJ, Huang SH, Kurapati N, Amemiya S, Leonard KC. Simultaneous Intelligent Imaging of Nanoscale Reactivity and Topography by Scanning Electrochemical Microscopy. Anal Chem 2021; 93:8906-8914. [PMID: 34129324 DOI: 10.1021/acs.analchem.1c01248] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Scanning electrochemical microscopy (SECM) enables reactivity and topography imaging of single nanostructures in the electrolyte solution. The in situ reactivity and topography, however, are convoluted in the real-time image, thus requiring another imaging method for subsequent deconvolution. Herein, we develop an intelligent mode of nanoscale SECM to simultaneously obtain separate reactivity and topography images of non-flat substrates with reactive and inert regions. Specifically, an ∼0.5 μm-diameter Pt tip approaches a substrate with an ∼0.15 μm-height active Au band adjacent to an ∼0.4 μm-wide slope of the inactive glass surface followed by a flat inactive glass region. The amperometric tip current versus tip-substrate distance is measured to observe feedback effects including redox-mediated electron tunneling from the substrate. The intelligent SECM software automatically terminates the tip approach depending on the local reactivity and topography of the substrate under the tip. The resultant short tip-substrate distances allow for non-contact and high-resolution imaging in contrast to other imaging modes based on approach curves. The numerical post-analysis of each approach curve locates the substrate under the tip for quantitative topography imaging and determines the tip current at a constant distance for topography-independent reactivity imaging. The nanoscale grooves are revealed by intelligent topography SECM imaging as compared to scanning electron microscopy and atomic force microscopy without reactivity information and as unnoticed by constant-height SECM imaging owing to the convolution of topography with reactivity. Additionally, intelligent reactivity imaging traces abrupt changes in the constant-distance tip current across the Au/glass boundary, which prevents constant-current SECM imaging.
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Affiliation(s)
- Dylan T Jantz
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering, University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas 66047, United States
| | - Ryan J Balla
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Siao-Han Huang
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Niraja Kurapati
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Kevin C Leonard
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering, University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas 66047, United States
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6
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Amemiya S. Nanoelectrochemical Study of Molecular Transport through the Nuclear Pore Complex. CHEM REC 2021; 21:1430-1441. [PMID: 33502100 PMCID: PMC8217113 DOI: 10.1002/tcr.202000175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 11/10/2022]
Abstract
The nuclear pore complex (NPC) is the proteinaceous nanopore that solely mediates the transport of both small molecules and macromolecules between the nucleus and cytoplasm of a eukaryotic cell to regulate gene expression. In this personal account, we introduce recent progress in our nanoelectrochemical study of molecular transport through the NPC. Our work represents the importance of chemistry in understanding and controlling of NPC-mediated molecular transport to enable the efficient and safe delivery of genetic therapeutics into the nucleus, thereby fundamentally contributing to human health. Specifically, we employ nanoscale scanning electrochemical microscopy to test our hypothesis that the nanopore of the NPC is divided by transport barriers concentrically into peripheral and central routes to efficiently mediate the bimodal traffic of protein transport and RNA export, respectively, through cooperative hydrophobic and electrostatic interactions.
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Affiliation(s)
- Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, 15260, PA
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7
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Shigyou K, Sun L, Yajima R, Takigaura S, Tajima M, Furusho H, Kikuchi Y, Miyazawa K, Fukuma T, Taoka A, Ando T, Watanabe S. Geometrical Characterization of Glass Nanopipettes with Sub-10 nm Pore Diameter by Transmission Electron Microscopy. Anal Chem 2020; 92:15388-15393. [PMID: 33205942 DOI: 10.1021/acs.analchem.0c02884] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Glass nanopipettes are widely used for various applications in nanosciences. In most of the applications, it is important to characterize their geometrical parameters, such as the aperture size and the inner cone angle at the tip region. For nanopipettes with sub-10 nm aperture and thin wall thickness, transmission electron microscopy (TEM) must be most instrumental in their precise geometrical measurement. However, this measurement has remained a challenge because heat generated by electron beam irradiation would largely deform sub-10 nm nanopipettes. Here, we provide methods for preparing TEM specimens that do not cause deformation of such tiny nanopipettes.
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Affiliation(s)
- Kazuki Shigyou
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Linhao Sun
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Riku Yajima
- Division of Nano Life Science, Graduate School of Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Shohei Takigaura
- Department of Physics, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Masashi Tajima
- College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Hirotoshi Furusho
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yousuke Kikuchi
- Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Keisuke Miyazawa
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Faculty of Frontier Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan
| | - Takeshi Fukuma
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Faculty of Frontier Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Azuma Taoka
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Toshio Ando
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Shinji Watanabe
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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8
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Rabinowitz J, Whittier E, Liu Z, Jayant K, Frank J, Shepard K. Nanobubble-controlled nanofluidic transport. SCIENCE ADVANCES 2020; 6:6/46/eabd0126. [PMID: 33188030 PMCID: PMC7673748 DOI: 10.1126/sciadv.abd0126] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/23/2020] [Indexed: 05/03/2023]
Abstract
Nanofluidic platforms offering tunable material transport are applicable in biosensing, chemical detection, and filtration. Prior studies have achieved selective and controllable ion transport through electrical, optical, or chemical gating of complex nanostructures. Here, we mechanically control nanofluidic transport using nanobubbles. When plugging nanochannels, nanobubbles rectify and occasionally enhance ionic currents in a geometry-dependent manner. These conductance effects arise from nanobubbles inducing surface-governed ion transport through interfacial electrolyte films residing between nanobubble surfaces and nanopipette walls. The nanobubbles investigated here are mechanically generated, made metastable by surface pinning, and verified with cryogenic transmission electron microscopy. Our findings are relevant to nanofluidic device engineering, three-phase interface properties, and nanopipette-based applications.
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Affiliation(s)
- Jake Rabinowitz
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Elizabeth Whittier
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Zheng Liu
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Krishna Jayant
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Joachim Frank
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Kenneth Shepard
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA.
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
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9
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Chen R, Alanis K, Welle TM, Shen M. Nanoelectrochemistry in the study of single-cell signaling. Anal Bioanal Chem 2020; 412:6121-6132. [PMID: 32424795 DOI: 10.1007/s00216-020-02655-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/02/2020] [Accepted: 04/08/2020] [Indexed: 12/28/2022]
Abstract
Label-free biosensing has been the dream of scientists and biotechnologists as reported by Vollmer and Arnold (Nat Methods 5:591-596, 2008). The ability of examining living cells is crucial to cell biology as noted by Fang (Int J Electrochem 2011:460850, 2011). Chemical measurement with electrodes is label-free and has demonstrated capability of studying living cells. In recent years, nanoelectrodes of different functionality have been developed. These nanometer-sized electrodes, coupled with scanning electrochemical microscopy (SECM), have further enabled nanometer spatial resolution study in aqueous environments. Developments in the field of nanoelectrochemistry have allowed measurement of signaling species at single cells, contributing to better understanding of cell biology. Leading studies using nanoelectrochemistry of a variety of cellular signaling molecules, including redox-active neurotransmitter (e.g., dopamine), non-redox-active neurotransmitter (e.g., acetylcholine), reactive oxygen species (ROS), and reactive nitrogen species (RNS), are reviewed here.
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Affiliation(s)
- Ran Chen
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL, 61801, USA
| | - Kristen Alanis
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL, 61801, USA
| | - Theresa M Welle
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL, 61801, USA
| | - Mei Shen
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL, 61801, USA.
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10
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Balla RJ, Jantz DT, Kurapati N, Chen R, Leonard KC, Amemiya S. Nanoscale Intelligent Imaging Based on Real-Time Analysis of Approach Curve by Scanning Electrochemical Microscopy. Anal Chem 2019; 91:10227-10235. [PMID: 31310104 DOI: 10.1021/acs.analchem.9b02361] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Scanning electrochemical microscopy (SECM) enables high-resolution imaging by examining the amperometric response of an ultramicroelectrode tip near a substrate. Spatial resolution, however, is compromised for nonflat substrates, where distances from a tip far exceed the tip size to avoid artifacts caused by the tip-substrate contact. Herein, we propose a new imaging mode of SECM based on real-time analysis of the approach curve to actively control nanoscale tip-substrate distances without contact. The power of this software-based method is demonstrated by imaging an insulating substrate with step edges using standard instrumentation without combination of another method for distance measurement, e.g., atomic force microscopy. An ∼500 nm diameter Pt tip approaches down to ∼50 nm from upper and lower terraces of a 500 nm height step edge, which are located by real-time theoretical fitting of an experimental approach curve to ensure the lack of electrochemical reactivity. The tip approach to the step edge can be terminated at <20 nm prior to the tip-substrate contact as soon as the theory deviates from the tip current, which is analyzed numerically afterward to locate the inert edge. The advantageous local adjustment of tip height and tip current at the final point of tip approach distinguishes the proposed imaging mode from other modes based on standard instrumentation. In addition, the glass sheath of the Pt tip is thinned to ∼150 nm to rarely contact the step edge, which is unavoidable and instantaneously detected as an abrupt change in the slope of approach curve to prevent damage of the fragile nanotip.
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Affiliation(s)
- Ryan J Balla
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Dylan T Jantz
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering , University of Kansas , 1501 Wakarusa Drive , Lawrence , Kansas 66047 , United States
| | - Niraja Kurapati
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Ran Chen
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
| | - Kevin C Leonard
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering , University of Kansas , 1501 Wakarusa Drive , Lawrence , Kansas 66047 , United States
| | - Shigeru Amemiya
- Department of Chemistry , University of Pittsburgh , 219 Parkman Avenue , Pittsburgh , Pennsylvania 15260 , United States
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11
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Pathirathna P, Balla RJ, Jantz DT, Kurapati N, Gramm ER, Leonard KC, Amemiya S. Probing High Permeability of Nuclear Pore Complexes by Scanning Electrochemical Microscopy: Ca 2+ Effects on Transport Barriers. Anal Chem 2019; 91:5446-5454. [PMID: 30907572 PMCID: PMC6535230 DOI: 10.1021/acs.analchem.9b00796] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The nuclear pore complex (NPC) solely mediates molecular transport between the nucleus and cytoplasm of a eukaryotic cell to play important biological and biomedical roles. However, it is not well-understood chemically how this biological nanopore selectively and efficiently transports various substances, including small molecules, proteins, and RNAs by using transport barriers that are rich in highly disordered repeats of hydrophobic phenylalanine and glycine intermingled with charged amino acids. Herein, we employ scanning electrochemical microscopy to image and measure the high permeability of NPCs to small redox molecules. The effective medium theory demonstrates that the measured permeability is controlled by diffusional translocation of probe molecules through water-filled nanopores without steric or electrostatic hindrance from hydrophobic or charged regions of transport barriers, respectively. However, the permeability of NPCs is reduced by a low millimolar concentration of Ca2+, which can interact with anionic regions of transport barriers to alter their spatial distributions within the nanopore. We employ atomic force microscopy to confirm that transport barriers of NPCs are dominantly recessed (∼80%) or entangled (∼20%) at the high Ca2+ level in contrast to authentic populations of entangled (∼50%), recessed (∼25%), and "plugged" (∼25%) conformations at a physiological Ca2+ level of submicromolar. We propose a model for synchronized Ca2+ effects on the conformation and permeability of NPCs, where transport barriers are viscosified to lower permeability. Significantly, this result supports a hypothesis that the functional structure of transport barriers is maintained not only by their hydrophobic regions, but also by charged regions.
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Affiliation(s)
- Pavithra Pathirathna
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260, United States
| | - Ryan J. Balla
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260, United States
| | - Dylan T. Jantz
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering, University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas 66047, United States
| | - Niraja Kurapati
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260, United States
| | - Erin R. Gramm
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260, United States
| | - Kevin C. Leonard
- Center for Environmentally Beneficial Catalysis, Department of Chemical and Petroleum Engineering, University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas 66047, United States
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260, United States
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12
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Puri SR, Kim J. Kinetics of Antimicrobial Drug Ion Transfer at a Water/Oil Interface Studied by Nanopipet Voltammetry. Anal Chem 2019; 91:1873-1879. [DOI: 10.1021/acs.analchem.8b03593] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Surendra Raj Puri
- Department of Chemistry, The University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Jiyeon Kim
- Department of Chemistry, The University of Rhode Island, Kingston, Rhode Island 02881, United States
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13
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Zhao Z, Leonard KC, Boika A. Hot-Tip Scanning Electrochemical Microscopy: Theory and Experiments Under Positive and Negative Feedback Conditions. Anal Chem 2019; 91:2970-2977. [DOI: 10.1021/acs.analchem.8b05192] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhiling Zhao
- Department of Chemistry, The University of Akron, Akron, Ohio 44325, United States
| | - Kevin C. Leonard
- Department of Chemical & Petroleum Engineering, Center for Environmentally Beneficial Catalysis, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Aliaksei Boika
- Department of Chemistry, The University of Akron, Akron, Ohio 44325, United States
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14
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Li P, He Q, Liu H, Liu Y, Su J, Tian N, Zhan D. Collision Incidents of Single Tetrahexahedral Platinum Nanocrystals Recorded by a Carbon Nanoelectrode. ChemElectroChem 2018. [DOI: 10.1002/celc.201800650] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pei Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
| | - Quanfeng He
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
| | - Hai‐Xia Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
- Key Laboratory of Mesoscopic Chemistry of MOE Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical EngineeringNanjing University Nanjing 210093 China
| | - Yunhua Liu
- National CAD Support Software Engineering Research CenterHuazhong University of Science and Technology Wuhan 430074 China
| | - Jian‐Jia Su
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
| | - Na Tian
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
| | - Dongping Zhan
- State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Centre of Chemistry for Energy Materials College of Chemistry and Chemical EngineeringXiamen University Xiamen 361005 China
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Shen M, Qu Z, DesLaurier J, Welle TM, Sweedler JV, Chen R. Single Synaptic Observation of Cholinergic Neurotransmission on Living Neurons: Concentration and Dynamics. J Am Chem Soc 2018; 140:7764-7768. [PMID: 29883110 DOI: 10.1021/jacs.8b01989] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Acetylcholine, the first neurotransmitter identified more than a century ago, plays critical roles in human activities and health; however, its synaptic concentration dynamics have remained unknown. Here, we demonstrate the in situ simultaneous measurements of synaptic cholinergic transmitter concentration and release dynamics. We used nanoscale electroanalytical methods: nanoITIES electrode of 15 nm in radius and nanoresolved scanning electrochemical microscopy (SECM). Time-resolved in situ measurements unveiled information on synaptic acetylcholine concentration and release dynamics of living Aplysia neurons. The measuring technique enabled the quantitative sensing of acetylcholine with negligible interference of other ionic and redox-active species. We measured cholinergic transmitter concentrations very close to the synapse, with values as high as 2.4 mM. We observed diverse synaptic transmitter concentration dynamics consisting of singlet, doublet and multiplet events with a signal-to-noise ratio of 6 to 130. The unprecedented details about synaptic neurotransmission unveiled are instrumental for understanding brain communication and diseases in a way distinctive from extra-synaptic studies.
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Affiliation(s)
- Mei Shen
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
| | - Zizheng Qu
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
| | - Justin DesLaurier
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
| | - Theresa M Welle
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
| | - Jonathan V Sweedler
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
| | - Ran Chen
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Matthews Avenue , Urbana , Illinois 61801 , United States
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16
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Advances and Perspectives in Chemical Imaging in Cellular Environments Using Electrochemical Methods. CHEMOSENSORS 2018. [DOI: 10.3390/chemosensors6020024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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