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Guerrette JP, Percival SJ, Zhang B. Voltammetric behavior of gold nanotrench electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:12218-12225. [PMID: 21866978 DOI: 10.1021/la2023743] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the fabrication and electrochemical response of a gold nanoband electrode located at the bottom of a glass/epoxy nanotrench, hereafter referred to as a gold nanotrench electrode. Gold nanotrench electrodes of 12.5 and 40 nm in width with various depths from a few tens of nanometers to approximately 4 μm are fabricated and further characterized by cyclic voltammetry. The fabrication of a Au nanotrench electrode follows a simple electrochemical etching process in which a small AC signal is applied to an inlaid Au nanoband electrode submersed in a NaCl solution. The voltammetric behavior of a Au nanotrench electrode is characterized by a quasi-steady-state response at lower scan rates (e.g., <1 V/s for a 12.5-nm-wide electrode). We present an analytical expression for the quasi-steady-state diffusion-limited current of the nanotrench electrode based upon the analysis of the mass-transport resistance. Finite-element simulation of steady-state and transient voltammetric responses of the nanotrench electrodes provides additional insights for the analytical model. Peak-shaped transient voltammetric responses were observed at scan rates as low as 5 V/s for both inlaid and nanotrench electrodes. This result may suggest that the exposed area of the nanoband electrode is much greater than that expected from the fabrication of the inlaid bands. However, the extent to which this is seen is greatly decreased in the nanotrench electrode by a smoothing effect during etching. Our results confirm previous reports of excess overhanging metal and delamination crack contributing significantly to the shape and magnitude of the voltammetric response.
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Affiliation(s)
- Joshua P Guerrette
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
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102
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103
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Real-time evaluation of nitric oxide (NO) levels in cortical and hippocampal areas with a nanopore-based electrochemical NO sensor. Neurosci Lett 2011; 498:22-5. [DOI: 10.1016/j.neulet.2011.04.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 04/07/2011] [Accepted: 04/20/2011] [Indexed: 11/21/2022]
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104
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Shim JH, Jang K, Lee Youngmi Lee C. Applications of Porous Pt-Filled Micropore Electrode: Direct Amperometric Glucose Detection and Potentiometric pH Sensing. ELECTROANAL 2011. [DOI: 10.1002/elan.201100165] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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105
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Cox JA, Wiaderek KM, Mehdi BL, Gudorf BP, Ranganathan D, Zamponi S, Berrettoni M. Influence of silanization on voltammetry at electrodes modified with silica films of controlled porosity formed by electrochemically initiated sol-gel processing. J Solid State Electrochem 2011. [DOI: 10.1007/s10008-011-1445-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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106
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Schibel AEP, Heider EC, Harris JM, White HS. Fluorescence microscopy of the pressure-dependent structure of lipid bilayers suspended across conical nanopores. J Am Chem Soc 2011; 133:7810-5. [PMID: 21542629 DOI: 10.1021/ja1117182] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Glass and fused-quartz nanopore membranes containing a single conically shaped pore are promising solid supports for lipid bilayer ion-channel recordings due to the high inherent stability of lipid bilayers suspended across the nanopore orifice, as well as the favorable electrical properties of glass and fused quartz. Fluorescence microscopy is used here to investigate the structure of the suspended lipid bilayer as a function of the pressure applied across a fused-quartz nanopore membrane. When a positive pressure is applied across the bilayer, from the nanopore interior relative to the exterior bulk solution, insertion or reconstitution of operative ion channels (e.g., α-hemolysin (α-HL) and gramicidin) in the bilayer is observed; conversely, reversing the direction of the applied pressure results in loss of all channel activity, although the bilayer remains intact. The dependence of the bilayer structure on pressure was explored by imaging the fluorescence intensity from Nile red dye doped into suspended 1,2-diphytanoyl-sn-glycero-3-phosphocholine bilayers, while simultaneously recording the activity of an α-HL channel. The fluorescence images suggest that a positive pressure results in compression of the bilayer leaflets and an increase in the bilayer curvature, making it suitable for ion-channel formation and activity. At negative pressure, the fluorescence images are consistent with separation of the lipid leaflets, resulting in the observed loss of the ion-channel activity. The fluorescence data indicate that the changes in the pressure-induced bilayer structure are reversible, consistent with the ability to repeatedly switch the ion-channel activity on and off by applying positive and negative pressures, respectively.
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Affiliation(s)
- Anna E P Schibel
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA
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107
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Lan WJ, Holden DA, Zhang B, White HS. Nanoparticle Transport in Conical-Shaped Nanopores. Anal Chem 2011; 83:3840-7. [DOI: 10.1021/ac200312n] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Wen-Jie Lan
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
| | - Deric A. Holden
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
| | - Bo Zhang
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
| | - Henry S. White
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, United States
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108
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Davenport M, Healy K, Siwy ZS. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes. NANOTECHNOLOGY 2011; 22:155301. [PMID: 21389573 DOI: 10.1088/0957-4484/22/15/155301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses.
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Affiliation(s)
- Matthew Davenport
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
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109
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Vogel R, Willmott G, Kozak D, Roberts GS, Anderson W, Groenewegen L, Glossop B, Barnett A, Turner A, Trau M. Quantitative sizing of nano/microparticles with a tunable elastomeric pore sensor. Anal Chem 2011; 83:3499-506. [PMID: 21434639 DOI: 10.1021/ac200195n] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The use of a "size-tunable" polyurethane resistive pulse sensor for quantitative sizing of nano- and microparticles is presented. A linear relationship, as first suggested by Maxwell, between particle volume and change in electric resistance across the pore was observed. Particle sizes were quantified for a given size-tunable membrane, by first creating a linear calibration curve to a series of monodisperse carboxylated polystyrene particles of various diameters and then applying this curve to calculate the size of "unknown" nanoparticles. The diameters of a selection of synthetic and biological particles, being PMMA and nonfunctionalized polystyrene particles, along with biological nanoparticles (adenovirus) were calculated using this methodology. Calculated particle diameters and coefficients of variation were shown to be in good agreement with both transmission electron microscopy and dynamic light scattering results.
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Affiliation(s)
- Robert Vogel
- School of Mathematics and Physics, The University of Queensland, St. Lucia QLD, Australia.
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110
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Abstract
Exploration of electrochemical properties in ultrasmall volumes is still an emerging area. It is not only of great importance for the fundamental research, but also endowed with practical significance in the area of bioanalysis and medicine. Microelectrodes with superior electrochemical characteristics and versatile configurations are suitable tools for the investigation in confined geometries, and remarkable progress involving both preparation methods and theoretical interpretation has been made during the last few decades. Despite this success, electrochemical studies in nanoscopic volumes are still highly challenging due to the less predictable situations in very limited spatial and temporal domains, as well as difficulty in micromanipulation at the nanoscale. In this mini-review, we will summarize the main strategies for this topic, briefly look through the recent advances, and specifically introduce the design and application of a new kind of on-chip ultrasmall electrochemical cells based on micro- and nanogap electrodes, which are prepared by photolithographic method with volume ranging from femtolitre to attolitre. Finally, the limits of current systems and the future perspectives of this field are discussed.
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Affiliation(s)
- Tao Li
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
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111
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112
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Schibel AEP, An N, Jin Q, Fleming AM, Burrows CJ, White HS. Nanopore detection of 8-oxo-7,8-dihydro-2'-deoxyguanosine in immobilized single-stranded DNA via adduct formation to the DNA damage site. J Am Chem Soc 2010; 132:17992-5. [PMID: 21138270 PMCID: PMC3021242 DOI: 10.1021/ja109501x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to detect DNA damage within the context of the surrounding sequence is an important goal in medical diagnosis and therapies, but there are no satisfactory methods available to detect a damaged base while providing sequence information. One of the most common base lesions is 8-oxo-7,8-dihydroguanine, which occurs during oxidation of guanine. In the work presented here, we demonstrate the detection of a single oxidative damage site using ion channel nanopore methods employing α-hemolysin. Hydantoin lesions produced from further oxidation of 8-oxo-7,8-dihydroguanine, as well as spirocyclic adducts produced from covalently attaching a primary amine to the spiroiminodihydantoin lesion, were detected by tethering the damaged DNA to streptavidin via a biotin linkage and capturing the DNA inside an α-hemolysin ion channel. Spirocyclic adducts, in both homo- and heteropolymer background single-stranded DNA sequences, produced current blockage levels differing by almost 10% from those of native base current blockage levels. These preliminary studies show the applicability of ion channel recordings not only for DNA sequencing, which has recently received much attention, but also for detecting DNA damage, which will be an important component to any sequencing efforts.
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Affiliation(s)
- Anna E. P. Schibel
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
| | - Na An
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
| | - Qian Jin
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
| | - Aaron M. Fleming
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
| | - Cynthia J. Burrows
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
| | - Henry S. White
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850
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113
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Chen Q, Liu J, Schibel AEP, White HS, Wu C. Translocation Dynamics of Poly(styrenesulfonic acid) through an α-Hemolysin Protein Nanopore. Macromolecules 2010. [DOI: 10.1021/ma1016117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qianjin Chen
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong
| | - Jin Liu
- Department of Chemistry, University of Utah, 315 S.1400 E, Salt Lake City, Utah 84112, United States
| | - Anna E. P. Schibel
- Department of Chemistry, University of Utah, 315 S.1400 E, Salt Lake City, Utah 84112, United States
| | - Henry S. White
- Department of Chemistry, University of Utah, 315 S.1400 E, Salt Lake City, Utah 84112, United States
| | - Chi Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong
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114
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Guerrette JP, Zhang B. Scan-Rate-Dependent Current Rectification of Cone-Shaped Silica Nanopores in Quartz Nanopipettes. J Am Chem Soc 2010; 132:17088-91. [DOI: 10.1021/ja1086497] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua P. Guerrette
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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115
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Abelow AE, Schepelina O, White RJ, Vallée-Bélisle A, Plaxco KW, Zharov I. Biomimetic glass nanopores employing aptamer gates responsive to a small molecule. Chem Commun (Camb) 2010; 46:7984-6. [PMID: 20865192 DOI: 10.1039/c0cc02649b] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the preparation of 20 and 65 nm radii glass nanopores whose surface is modified with DNA aptamers controlling the molecular transport through the nanopores in response to small molecule binding.
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Affiliation(s)
- Alexis E Abelow
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, USA
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116
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Lantiat D, Vivier V, Laberty-Robert C, Grosso D, Sanchez C. Gold nanoelectrode arrays and their evaluation by impedance spectroscopy and cyclic voltammetry. Chemphyschem 2010; 11:1971-7. [PMID: 20512837 DOI: 10.1002/cphc.200900929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A sol-gel strategy is developed to fabricate highly regular Au nanoelectrode arrays (NEAs) consisting of a nanoperforated ultrathin membrane of ZrO(2), which exhibits a well-ordered array of pores (65+/-5) nm in diameter with a mean center-to-center distance of (110+/-10) nm, on a polycrystalline gold surface. The structural properties are investigated by field-emission scanning electron microscopy (FE-SEM), while grazing incidence small-angle X-ray scattering (GISAXS) is used to assess the thickness homogeneity and the period of the array of electrodes. In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are carried out to describe quantitatively the accessibility, electrochemical behavior, and diffusion processes of the gold NEA. A model applying parameters obtained from FE-SEM, CV, and EIS analyses is proposed to simulate the experimental results. A fairly good agreement between the experimental and the simulated data is obtained, thus allowing the deconvolution of the different diffusion regimes at the NEA.
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Affiliation(s)
- David Lantiat
- LCMCP, UMR7574 CNRS/UPMC, Collège de France, 11 place Marcellin Berthelot, 75231 Paris Cedex 05, France
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117
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Baranski AS, Boika A. Effect of Large-Amplitude Alternating Current Modulation on Apparent Reversibility of Electrode Processes. Anal Chem 2010; 82:8137-45. [DOI: 10.1021/ac1014222] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrzej S. Baranski
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada, S7N 5C9
| | - Aliaksei Boika
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada, S7N 5C9
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118
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Trends in computational simulations of electrochemical processes under hydrodynamic flow in microchannels. Anal Bioanal Chem 2010; 399:183-90. [DOI: 10.1007/s00216-010-4070-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 07/27/2010] [Accepted: 07/29/2010] [Indexed: 10/19/2022]
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119
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Abstract
Here we report the fabrication of two types of microirradiators, consisting of a recessed disk and protruding wire with low-beta-energy radionuclide Ni-63 electrodeposited onto a 25 microm diameter Pt wire. Ni-63 is constricted to a small surface area of the microelectrode; hence, this tool provides a means of delivery of localized, large dose density of beta radiation to the object but a minimal dose exposure to the user. The activity levels of Ni-63 emitted from the recessed disk and protruding wire are 0.25 and 1 Bq, respectively. The corresponding beta particles flux levels emitted from the recessed disk and protruding wire are 51 and 11 kBq/cm(2), respectively. These values, measured experimentally using liquid scintillation counting, fit very well the expected values of activity for each microirradiator, calculated considering the self-absorption effect, typical for low-energy beta particles. In order to determine the optimal configuration the dose rates for varying distances from the object were calculated.
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Affiliation(s)
- Jennifer Steeb
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332-0400, USA
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120
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Jena BK, Percival SJ, Zhang B. Au Disk Nanoelectrode by Electrochemical Deposition in a Nanopore. Anal Chem 2010; 82:6737-43. [DOI: 10.1021/ac101261m] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Bikash Kumar Jena
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Stephen J. Percival
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
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121
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Højgaard Olesen L, Bazant MZ, Bruus H. Strongly nonlinear dynamics of electrolytes in large ac voltages. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:011501. [PMID: 20866619 DOI: 10.1103/physreve.82.011501] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 05/12/2010] [Indexed: 05/29/2023]
Abstract
We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two features--significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination" since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and collapse of space-charge layers, even in the absence of any net Faradaic current through the cell. We also predict that steric effects of finite ion sizes (going beyond dilute-solution theory) act to suppress the strongly nonlinear regime in the limit of concentrated electrolytes, ionic liquids, and molten salts. Beyond the model problem, our reduced equations for thin double layers, based on uniformly valid matched asymptotic expansions, provide a useful mathematical framework to describe additional nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena.
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Affiliation(s)
- Laurits Højgaard Olesen
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech Building 345 East, DK-2800 Kongens Lyngby, Denmark
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122
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Peinetti A, González G, Battaglini F. Modeling the Electrochemical Response of Mesoporous Materials Toward Its Application to Biomolecular Detection. ELECTROANAL 2010. [DOI: 10.1002/elan.200900572] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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123
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Feng J, Liu J, Wu B, Wang G. Impedance Characteristics of Amine Modified Single Glass Nanopores. Anal Chem 2010; 82:4520-8. [DOI: 10.1021/ac100440z] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jingyu Feng
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | - Juan Liu
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | - Baohua Wu
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | - Gangli Wang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
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124
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Hesse WR, Freedman KJ, Yi DK, Ahn CW, Kim M. Bacterial nanofluidic structures for medicine and engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:895-909. [PMID: 20397205 DOI: 10.1002/smll.200901576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Bacteria are microscopic, single-celled organisms that utilize a variety of nanofluidic structures. One of the best known and widely used nanofluidic structures that are derived from bacteria is the alpha-hemolysin pore. This pore, which self-assembles in lipid bilayers, has been used for a wide variety of sensing applications, most notably, DNA sensing. Synthetic pores drilled in a wide variety of materials, such as silicon nitride and polymers have been developed that use inspiration from the alpha-hemolysin pore. Higher-aspect-ratio nanofluidic structures, akin to nanotubes, are also synthesized by bacteria. Examples of such structures include those that are associated with bacterial transport apparatus, such as pili, and are used by bacteria to facilitate the transfer of genetic material from one bacterium to another. Flagella, and its associated structures, such as the rod and hook, are also tubular nanostructures, through which the protein, flagellin, travels to assemble the flagellum. Genetic engineering allows for the creation of modified bacterial nanopores and nanotubes that can be used for a variety of medical and engineering purposes.
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Affiliation(s)
- William R Hesse
- Department of Mechanical Engineering and Mechanics Drexel University 3141 Chestnut St., Philadelphia, PA 19104, USA
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125
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Cao XH, Zhang LX, Cai WP, Li YQ. Amperometric sensing of dopamine using a single-walled carbon nanotube covalently attached to a conical glass micropore electrode. Electrochem commun 2010. [DOI: 10.1016/j.elecom.2010.01.038] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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126
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Shim JH, Lee Y. Amperometric nitric oxide microsensor based on nanopore-platinized platinum: the application for imaging NO concentrations. Anal Chem 2010; 81:8571-6. [PMID: 19775121 DOI: 10.1021/ac901552m] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper reports an amperometric nitric oxide (NO) microsensor based on a cone-shaped nanopore-platinized Pt working electrode. The senor was fabricated using the following procedure: (1) a parent nanodisk electrode was prepared by polishing an etched Pt wire (radius = 12.5 microm; dimension of etched tip end point <10 nm) embedded in a glass capillary, (2) the nanodisk Pt was further etched to produce a nanopore (pore opening radius <1 microm; pore depth approximately 30 microm), (3) the Pt base surface in the nanopore electrode was platinized electrochemically to improve the sensor sensitivity, and (4) silanization and further modification with the electropolymerized polymeric film [poly(5-amino-1-naphthol)] on the nanopore-platinized Pt electrode were carried out to obtain the sensor selectivity to NO. The analytical performance of the sensor was characterized. For example, a sensor with a pore opening radius of 797 nm exhibited a decent linear dynamic range (at least for 0.2-1.8 microM), detection limit of < approximately 32 nM, response time (t(90%)) of < approximately 5 s, and sensitivity of 6.5 +/- 0.02 pA/nM. This sensor was used successfully as a NO-selective probe tip in scanning electrochemical microscopy (SECM) to obtain a two-dimensional image of the local NO concentrations for an inlaid NO-emitting microdisk film (radius = 12.5 microm) on a glass substrate.
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Affiliation(s)
- Jun Ho Shim
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, USA
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127
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Mallon CT, Zuliani C, Keyes TE, Forster RJ. Single nanocavity electrodes: fabrication, electrochemical and photonic properties. Chem Commun (Camb) 2010; 46:7109-11. [DOI: 10.1039/c0cc00418a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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128
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Abstract
Molecular-scale pore structures, called nanopores, can be assembled by protein ion channels through genetic engineering or be artificially fabricated on solid substrates using fashion nanotechnology. When target molecules interact with the functionalized lumen of a nanopore, they characteristically block the ion pathway. The resulting conductance changes allow for identification of single molecules and quantification of target species in the mixture. In this review, we first overview nanopore-based sensory techniques that have been created for the detection of myriad biomedical targets, from metal ions, drug compounds, and cellular second messengers to proteins and DNA. Then we introduce our recent discoveries in nanopore single molecule detection: (1) using the protein nanopore to study folding/unfolding of the G-quadruplex aptamer; (2) creating a portable and durable biochip that is integrated with a single-protein pore sensor (this chip is compared with recently developed protein pore sensors based on stabilized bilayers on glass nanopore membranes and droplet interface bilayer); and (3) creating a glass nanopore-terminated probe for single-molecule DNA detection, chiral enantiomer discrimination, and identification of the bioterrorist agent ricin with an aptamer-encoded nanopore.
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Affiliation(s)
- Li-Qun Gu
- Biological Engineering and Dalton Cardiovascular Research Center, University of Missouri, 134 Research Park, Columbia, Missouri 65211, USA.
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129
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Sun P. Cylindrical Nanopore Electrode and Its Application to the Study of Electrochemical Reaction in Several Hundred Attoliter Volume. Anal Chem 2009; 82:276-81. [DOI: 10.1021/ac9019335] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Peng Sun
- Department of Chemistry, East Tennessee State University, Box 70695, Johnson City, Tennessee 37614
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130
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Fang D, Jiang D, Lu H, Chiel HJ, Kelley TJ, Burgess JD. Observation of cellular cholesterol efflux at microcavity electrodes. J Am Chem Soc 2009; 131:12038-9. [PMID: 19670860 DOI: 10.1021/ja903684f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cholesterol oxidase modified platinum microcavity electrodes are used to measure cholesterol efflux from the plasma membrane surface of a single neuron in the buccal ganglion of Aplysia at room temperature. A background subtraction analog chronocoulometry method is used to measure hydrogen peroxide accumulation in the microcavity volume resulting from cellular cholesterol efflux and enzymatic oxidation. The data are consistent with the aqueous diffusion model for cellular cholesterol efflux where plasma membrane cholesterol undergoes exchange with solution phase cholesterol.
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Affiliation(s)
- Danjun Fang
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
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131
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Abstract
Recently reported nanofluidic diodes with highly nonlinear current-voltage characteristics offer a unique possibility to construct different biosensors. These sensors are based on local changes of the surface charge on walls of single conical nanopores induced by binding of an analyte. The analyte binding can be detected as a change of the ion-current rectification of single nanopores defined as a ratio of currents for voltages of one polarity, and currents for voltages of the opposite polarity. In this article, we provided both modeling and experimental studies of various biosensing routes based on monitoring changes of the rectification degree in nanofluidic diodes used as a biosensing platform. A prototype of a sensor for the capsular poly gamma-D-glutamic acid (gammaDPGA) from Bacillus anthracis is presented. The nanopore used for the sensing was locally modified with the monoclonal antibody for gammaDPGA. The proof of principle of the rectification degree-based sensing was further shown by preparation of sensors for avidin and streptavidin. Our devices also allowed for determination of the isoelectric point of the minute amounts of proteins immobilized on the surface.
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Affiliation(s)
- Ivan Vlassiouk
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
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132
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Ding S, Gao C, Gu LQ. Capturing single molecules of immunoglobulin and ricin with an aptamer-encoded glass nanopore. Anal Chem 2009; 81:6649-55. [PMID: 19627120 PMCID: PMC3009471 DOI: 10.1021/ac9006705] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanopore-based single-molecule biosensors have been extensively studied. Protein pores that have receptors attached to them are target-selective, but their real-time applications are limited by the fragility of the lipid membrane into which the protein pores are embedded. Synthetic nanopores are more stable and provide flexible pore sizes, but the selectivity is low when detecting in the translocation mode. In spite of modifications with probing molecules, such as antibodies, to potentiate specific targeting, these nanopores fail to bind individual target molecules. Distinguishing between binding and translocation blocks remains unsolved. Here, we propose an aptamer-encoded nanopore that overcomes these challenges. Aptamers are well-known probing oligonucleotides that have high sensitivity and selectivity. In contrast to antibodies, aptamers are much smaller than their targets, rendering target blockades in the nanopore much more distinguishable. We used aptamer-encoded nanopores to detect single molecules of immunoglobulin E and the bioterrorist agent ricin, sequentially captured by the immobilized aptamer in the sensing zone of the pore. The functional nanopore also probed sequence-dependent aptamer-protein interactions. These findings will facilitate the development of a universal nanopore for multitarget detection.
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Affiliation(s)
- Shu Ding
- Department of Biological Engineering and Dalton Cardiovascular Research Center, University of Missouri – Columbia, MO 65211, USA
| | - Changlu Gao
- Department of Biological Engineering and Dalton Cardiovascular Research Center, University of Missouri – Columbia, MO 65211, USA
| | - Li-Qun Gu
- Department of Biological Engineering and Dalton Cardiovascular Research Center, University of Missouri – Columbia, MO 65211, USA
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133
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Amatore C, Oleinick AI, Svir I. Numerical simulation of diffusion processes at recessed disk microelectrode arrays using the quasi-conformal mapping approach. Anal Chem 2009; 81:4397-405. [PMID: 19402648 DOI: 10.1021/ac9003419] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we present a theoretical analysis of diffusion processes at arrays of recessed microelectrodes and evaluate the dependence of these processes on the main geometrical parameters (distance between electrodes in the array and slope of side walls of conical recesses) of this complex system. To allow for faster computation time and excellent accuracy, numerical simulations were performed upon transforming the real space allowed for diffusion using a quasi-conformal mapping introduced for this array geometry in our previous work (Amatore, C., Oleinick, A. I. and Svir, I. J. Electroanal. Chem. 2006, 597, 77-85). The applied quasi-conformal mapping is perfectly suited to the considered microelectrode array geometry and ensures that the abrupt change of boundary conditions reflecting the contorted geometries of the considered microelectrode array are treated efficiently and precisely in the simulations.
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Affiliation(s)
- C Amatore
- Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640 Pasteur, 24 rue Lhomond, 75231 Paris Cedex 05, France.
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134
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Yang C, Sun P. Fabrication and Characterization of a Dual Submicrometer-Sized Electrode. Anal Chem 2009; 81:7496-500. [DOI: 10.1021/ac901099n] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chenxi Yang
- Department of Chemistry, Box 70695, East Tennessee State University, Johnson City, Tennessee 37614
| | - Peng Sun
- Department of Chemistry, Box 70695, East Tennessee State University, Johnson City, Tennessee 37614
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135
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Zhang B, Wood M, Lee H. A Silica Nanochannel and Its Applications in Sensing and Molecular Transport. Anal Chem 2009; 81:5541-8. [DOI: 10.1021/ac9009148] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Marissa Wood
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Hyunae Lee
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
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136
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Maire HC, Ibrahim S, Li Y, Ito T. Effects of substrate roughness on the orientation of cylindrical domains in thin films of a polystyrene–poly(methylmethacrylate) diblock copolymer studied using atomic force microscopy and cyclic voltammetry. POLYMER 2009. [DOI: 10.1016/j.polymer.2009.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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137
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Guo J, Lindner E. Cyclic Voltammetry at Shallow Recessed Microdisc Electrode: Theoretical and Experimental Study. J Electroanal Chem (Lausanne) 2009; 629:180-184. [PMID: 20160948 PMCID: PMC2766860 DOI: 10.1016/j.jelechem.2009.01.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study focuses on the cyclic voltammetry behavior at shallow recessed microdisc electrode, particularly on the transition from cottrellian behavior to steady state behavior. Diffusion to the inlaid and recessed microdisc electrode is simulated. From the shape of the CVs, for a given radius and potential scan rate, the transition time from planar diffusion to hemispherical diffusion presents a minimum as the recess increases. Theoretical prediction was confirmed by fitting the simulated CVs with experimental results. Dimensionless transition scan rate has been defined and determined by simulation for inlaid and recessed microdisc electrodes.
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Affiliation(s)
- Jidong Guo
- Department of Biomedical Engineering, University of Memphis 330 Engineering Technology, Memphis, TN 38152, USA
| | - Ernő Lindner
- Department of Biomedical Engineering, University of Memphis 330 Engineering Technology, Memphis, TN 38152, USA
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138
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Kawano R, Schibel AEP, Cauley C, White HS. Controlling the translocation of single-stranded DNA through alpha-hemolysin ion channels using viscosity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:1233-1237. [PMID: 19138164 DOI: 10.1021/la803556p] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Translocation of single-stranded DNA through alpha-hemolysin (alpha-HL) channels is investigated in glycerol/water mixtures containing 1 M KCl. Experiments using glass nanopore membranes as the lipid bilayer support demonstrate that the translocation velocities of poly(deoxyadenylic acid), poly(deoxycytidylic acid), and poly(deoxythymidylic acid) 50-mers are decreased by a factor of approximately 20 in a 63/37 (vol %) glycerol/water mixture, relative to aqueous solutions. The ion conductance of alpha-HL and the entry rate of the polynucleotides into the protein channel also decrease with increasing viscosity. Precise control of translocation parameters by adjusting viscosity provides a potential means to improve sequencing methods based on ion channel recordings.
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Affiliation(s)
- Ryuji Kawano
- Department of Chemistry, University of Utah, 315S. 1400E, Salt Lake City, Utah 84112, USA.
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139
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Amatore C, Oleinick AI, Svir I. Theory of Ion Transport in Electrochemically Switchable Nanoporous Metallized Membranes. Chemphyschem 2009; 10:211-21. [DOI: 10.1002/cphc.200800481] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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140
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Gao C, Ding S, Tan Q, Gu LQ. Method of creating a nanopore-terminated probe for single-molecule enantiomer discrimination. Anal Chem 2009; 81:80-6. [PMID: 19061410 PMCID: PMC2642537 DOI: 10.1021/ac802348r] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nanopores are increasingly utilized as tools for single-molecule detection in biotechnology. Many nanopores are fabricated through procedures that require special materials, expensive facilities and experienced operators, which limit their usefulness on a wider scale. We have developed a simple method of fabricating a robust, low-noise nanopore by externally penetrating a nanocavity enclosed in the terminal of a capillary pipet. The nanocavity was shown to have a pore size on the scale of a single molecule, verified by translocation of molecules of known sizes, including double-stranded DNA (2 nm), gold nanoparticles (10 nm), and ring-shaped cyclodextrin (1.5 nm). The small pore size allows entrapment of a single cyclodextrin molecule. The glass nanopore with a trapped cyclodextrin proves useful in single-molecule discrimination of chiral enantiomers.
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Affiliation(s)
- Changlu Gao
- Department of Biological Engineering and Dalton Cardiovascular Research Center, University of Missouri-Columbia, Missouri 65211, USA
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141
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White HS, Bund A. Mechanism of electrostatic gating at conical glass nanopore electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:12062-12067. [PMID: 18811220 DOI: 10.1021/la801776w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The mechanism of molecule-based electrostatic gating of redox fluxes at conical glass nanopore (GNP) electrodes has been investigated using finite-element simulations. The results demonstrate that the fluxes of cationic redox molecules through the nanopore orifice can be reduced to negligibly small values when the surface charge of the nanopore is switched from a negative to a positive value. Electrostatic charge reversal can be affected by ionization of surface-bound moieties in response to environmental stimuli (e.g., photoionization or acid protonation), but only if the negative charge of the glass is included in the analysis. Numerical simulations of the responses of GNP electrodes are based on a simultaneous solution of the Poisson and Nernst-Planck equations and are in excellent agreement with our previously reported experimental results for electrostatic gating of the fluxes of Ru(NH 3) 6 (3+) and Fe(bpy) 3 (2+) at GNP electrodes with orifice radii between 15 and 100 nm. The gating mechanism is discussed in terms of three components: (1) migration of ionic redox species in the depletion layer adjacent to the electrode surface; (2) migrational transport along the charged pore walls; (3) electrostatic rejection of charged molecules at the pore orifice. The numerical results indicate that all three components are operative, but that ion migration along the pore walls is dominant.
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Affiliation(s)
- Henry S White
- Chemistry Department, University of Utah, Salt Lake City, Utah 84112, USA.
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142
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Boika A, Baranski AS. Dielectrophoretic and Electrothermal Effects at Alternating Current Heated Disk Microelectrodes. Anal Chem 2008; 80:7392-400. [DOI: 10.1021/ac801094s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aliaksei Boika
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada, S7N 5C9
| | - Andrzej S. Baranski
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada, S7N 5C9
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143
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Li Y, Ito T. Surface chemical functionalization of cylindrical nanopores derived from a polystyrene-poly(methylmethacrylate) diblock copolymer via amidation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8959-8963. [PMID: 18590296 DOI: 10.1021/la800992f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This paper demonstrated covalent functionalization of surface -COOH groups on cylindrical nanopores derived from a polystyrene-poly(methylmethacrylate) diblock copolymer (PS- b-PMMA) via amidation mediated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The surface functionalization led to conversion of the surface charge of the nanopores and also to the shrinkage of effective pore radius, as verified using cyclic voltammetry for PS- b-PMMA-derived nanoporous films immobilized on gold substrates. For native PS- b-PMMA-derived nanoporous films, the redox current of anionic Fe(CN) 6 (3-) decreased with increasing solution pH due to the deprotonation of the surface -COOH groups, whereas those of cationic Ru(NH 3) 6 3+ and uncharged 1,1'-ferrocenedimethanol (Fc(CH 2OH) 2) were similar regardless of pH. In contrast, upon EDC-mediated amidation of the nanopore surface with ethylenediamine, the redox current of Ru(NH 3) 6 3+ decreased with decreasing pH and those of Fe(CN) 6 (3-) and Fc(CH 2OH) 2 were independent of pH. The decrease in redox current of Ru(NH 3) 6 3+ at acidic pH was consistent with the presence of -NH 2 groups on the nanopore surface as a result of the covalent immobilization of ethylenediamine. Furthermore, the redox current of Fc(CH 2OH) 2 decreased upon amidation of the nanopores with tetraethyleneglycol monoamine ((PEO) 4NH 2), reflecting the shrinkage of the effective pore radius. The control of the surface charge and effective radius of the nanopores via EDC-mediated amidation will provide a simple means for controlling the selectivity of molecular mass transport through PS- b-PMMA-derived nanopores.
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Affiliation(s)
- Yongxin Li
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
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144
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Zhang Y, Zhou J, Lin L, Lin Z. Determination of Electrochemical Electron‐Transfer Reaction Standard Rate Constants at Nanoelectrodes: Standard Rate Constants for Ferrocenylmethyltrimethylammonium(III)/(II) and Hexacyanoferrate(III)/(II). ELECTROANAL 2008. [DOI: 10.1002/elan.200804198] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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145
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146
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Sun P, Mirkin MV. Electrochemistry of Individual Molecules in Zeptoliter Volumes. J Am Chem Soc 2008; 130:8241-50. [DOI: 10.1021/ja711088j] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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147
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Murray RW. Nanoelectrochemistry: Metal Nanoparticles, Nanoelectrodes, and Nanopores. Chem Rev 2008; 108:2688-720. [DOI: 10.1021/cr068077e] [Citation(s) in RCA: 963] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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148
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Han A, Creus M, Schürmann G, Linder V, Ward TR, de Rooij NF, Staufer U. Label-free detection of single protein molecules and protein-protein interactions using synthetic nanopores. Anal Chem 2008; 80:4651-8. [PMID: 18470996 DOI: 10.1021/ac7025207] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nanofabricated pores in 20 nm-thick silicon nitride membranes were used to probe various protein analytes as well as to perform an antigen-antibody binding assay. A two-compartment electrochemical cell was separated by a single nanopore, 28 nm in diameter. Adding proteins to one compartment caused current perturbations in the ion current flowing through the pore. These perturbations correlated with both the charge and the size of the protein or of a protein-protein complex. The potential of this nanotechnology for studying protein-protein interactions is highlighted with the sensitive detection of beta-human chorionic gonadotropin, a hormone and clinical biomarker of pregnancy, by monitoring in real time and at a molecular level the formation of a complex between hormones and antibodies in solution. In this form, the assay compared advantageously to immunoassays, with the important difference that labels, immobilization, or amplification steps were no longer needed. In conclusion, we present proof-of-principle that properties of proteins and their interactions can be investigated in solution using synthetic nanopores and that these interactions can be exploited to measure protein concentrations accurately.
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Affiliation(s)
- Anpan Han
- Institute of Microtechnology, University of Neuchâtel, Rue Jaquet-Droz 1, P.O. Box 526, CH-2002 Neuchâtel, Switzerland
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149
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Zhang B, Adams KL, Luber SJ, Eves DJ, Heien ML, Ewing AG. Spatially and temporally resolved single-cell exocytosis utilizing individually addressable carbon microelectrode arrays. Anal Chem 2008; 80:1394-400. [PMID: 18232712 DOI: 10.1021/ac702409s] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the fabrication and characterization of carbon microelectrode arrays (MEAs) and their application to spatially and temporally resolve neurotransmitter release from single pheochromocytoma (PC12) cells. The carbon MEAs are composed of individually addressable 2.5-mum-radius microdisks embedded in glass. The fabrication involves pulling a multibarrel glass capillary containing a single carbon fiber in each barrel into a sharp tip, followed by beveling the electrode tip to form an array (10-20 microm) of carbon microdisks. This simple fabrication procedure eliminates the need for complicated wiring of the independent electrodes, thus allowing preparation of high-density individually addressable microelectrodes. The carbon MEAs have been characterized using scanning electron microscopy, steady-state and fast-scan voltammetry, and numerical simulations. Amperometric results show that subcellular heterogeneity in single-cell exocytosis can be electrochemically detected with MEAs. These ultrasmall electrochemical probes are suitable for detecting fast chemical events in tight spaces, as well as for developing multifunctional electrochemical microsensors.
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Affiliation(s)
- Bo Zhang
- Department of Chemistry, 104 Chemistry Research Building, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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150
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Jia WZ, Wang K, Zhu ZJ, Song HT, Xia XH. One-step immobilization of glucose oxidase in a silica matrix on a Pt electrode by an electrochemically induced sol-gel process. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:11896-11900. [PMID: 17929847 DOI: 10.1021/la7020269] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate here that the electrochemical generation of hydroxyl ions and hydrogen bubbles can be used to induce the synthesis of enzyme- or protein-encapsulated 3D porous silica structure on the surface of noble metal electrodes. In the present work, the one-step synthesis of a glucose oxidase (GOD)-encapsulated silica matrix on a platinum electrode is presented. In this process, glucose oxidase was mixed with ethanol and TEOS to form a doped precursory sol solution. The electrochemically generated hydrogen bubbles at negative potentials assisted the formation of the porous structure of a GOD-encapsulated silica gel, and then the one-step immobilization of enzyme into the silica matrix was achieved. Scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) characterizations showed that the GOD-encapsulated silica matrix adhered to the electrode surface effectively and had an interconnected porous structure. Because the pores started at the electrode surface, their sizes increased gradually along the distance away from the electrode and reached maximum at the solution side, and effective mass transport to the electrode surface could be achieved. The entrapped enzyme in the silica matrix retained its activity. The present glucose biosensor had a short response time of 2 s and showed a linear response to glucose from 0 to 10 mM with a correlation coefficient of 0.9932. The detection limit was estimated to be 0.01 mM at a signal-to-noise ratio of 3. The apparent Michaelis-Menten constant (K m app) and the maximum current density were determined to be 20.3 mM and 112.4 microA cm-2, respectively. The present method offers a facile way to fabricate biosensors and bioelectronic devices in situ.
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Affiliation(s)
- Wen-Zhi Jia
- Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China
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