Fabrication and Characterization of Nanopore-Array Electrodes

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Fabrication and Characterization of
Nanopore-Array Electrodes
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Takashi Ito
Department of Chemistry, Kansas State University
Softmatter miniconference, KSU-Physics, May 16,
2007
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Nanopore-Array Electrodes (NAEs)
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1. An array of parallel cylindrical nanopores
Good model to study the mass transport
behaviors (fluid dynamic simulations)
Well-defined control of molecular interactions by
surface modification Relatively easy
preparation Larger electrochemical signals no
difficulty to find nanopores for fluorescence
microscopy
2. Insulator-based nanopores
Control the electric field in the pores and
thus molecular flow (electrokinetic effects)
3. Nanopores immobilized on an electrode
Support a nanoporous membrane wider thickness
range Preconcentrate analytes (via
electrokinetic effects and via binding sites
immobilized on it) Detect the molecules within
the nanopores
4. Methods to measure mass transport
Electrochemistry quick, quantitative, suitable
for the future sensor applications
Fluorescence directly see molecular behaviors,
information on molecular structure
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Issues to be Studied in this Project
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1. Clarify chemistry within polymer-based
cylindrical nanometer-scale pores
Chemistry covalent reactions on nanopore
surface, chemical interactions (mass transport,
entrapment) Mass transport behaviors of
molecules and biomolecules in the
nanopores chemical interactions, steric effects,
electrokinetic effects
2. Develop new analytical methods for
biomolecules (proteins, oligonucleotides and
viruses) using the nanopores
Chemical sensors, biosensors Chemical
separation
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Previous Achievements and Ongoing Topics
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1. To establish simple and reproducible ways to
prepare nanopore-array electrodes
Diblock copolymer
Track-etched membranes
2. To establish ways to characterize the
nanopore-array electrodes nannoporous structure
electrochemistry (in addition to AFM, EM,
ellipsometry, IR,)
Ito, T. Audi, A. A. Dible, G. P. Anal. Chem.
2006, 78, 7048-7053.
3. To control chemical interactions within
nanopores
identify chemical functional groups (nanopores
from a diblock copolymer) control chemical
modification (covalent polymer adsorption) in
particular, reduction of nonspecific adsorption
(PEG?)
4. To measure molecular mass transport and
entrapment in nanopores
electrochemistry fluorescence (single
molecule spectroscopy, with Dr. Higgins)
5. To demonstrate chemical sensing using
nanopore-array electrodes
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Other Projects in Itos Group
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Interdisciplinary research involving analytical
chemistry and nanotechnologies
My Previous Works (except electrochemistry-related
works)
1. Carbon Nanotube-Based Coulter Nanoparticle
Counters
2. Molecular STM Tips for Single Molecule
Discrimination
3. Chemical Force Microscopy
Ito, T. Namba, M. Bühlmann, P. Umezawa, Y.
Langmuir 1997, 13, 4323. Ito, T. Citterio, D.
Bühlmann, P. Umezawa, Y. Langmuir 1999, 15, 2788.
Ito, T. Sun, L. Henriquez, R. R. Crooks, R. M.
Acc. Chem. Res. 2004, 37, 937.
Nishino, T. Ito, T. Umezawa, Y. Proc. Natl.
Acad. Sci. USA 2005, 102, 5659.
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Instruments Techniques in Itos Group
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For my near-future projects
Relatively large biomolecules (or their
assemblies except DNA gt 5 nm in diameter). -
Their dynamic properties (structural change,
deformation, denature) is medically or
biologically important. - They are available
commercially or through collaboration. - They
can be fluorescently labeled (e.g., for FRET
experiments).