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Research Interests
Polymers with unusual electrical or optical
properties; biomaterials for tissue engineering and
regenerative medicine; electric field-mediated processing (electrospinning
of nano- and micro fibers and morphology modulation in
polymer blends); polymer-based microfluidic platforms;
polymer product design
Overview of Research
1. Polymers in Medicine
Over the past several years, we have been
involved in the development of electrostatic spinning (electrospinning)
as a method of fabrication of scaffolds for tissue
engineering, drug delivery, and related applications. The
motivation is to create bio-mimicking fibers in a diameter
range (ca. 20-100 nm) difficult to access by conventional
fiber processing methods. Our group's long-term focus is
directed toward exploitation of nanofiber scaffolds for a
better understanding of processes in the central nervous
system or CNS (the brain and spinal cord), and ultimately to
contribute to restoration of function impaired by
CNS-related diseases. We believe that much can be learned
about fundamental cellular processes if cells are presented
with the appropriate 3-D scaffold on which to grow,
proliferate, and communicate. We are also interested in the
development of platforms for cell encapsulation and, longer
term, the fabrication of 'artificial cells.' Toward that
end, attention is being directed toward the construction of
novel bio-fuel cells.
2. Polymers in Electrochemical
Devices: Fuel Cells and Batteries
A growing interest exists in the
development of new materials with improved properties for
various energy storage and conversion devices, including
batteries, fuel cells, and supercapacitors. Over the past 10
years, our group has helped to develop new, low-cost
proton-conducting membranes based on simple random and block
copolymer structures containing partially sulfonated styrene
units. We learned a great deal about the influence of ionic
aggregation and morphology in these materials, and are
beginning to apply this knowledge to the design of new
polymers with, for example, low permeation to methanol for
use in direct methanol fuel cells. In addition, we are
exploring the use of these and other polymer electrolytes as
hosts for luminescent dyes for the development of
electroluminescent devices with tunable emission profiles.
We have recently embarked on a program to exploit
electrostatic processing, specifically electrospraying and
electrospinning as a general approach for the fabrication of
electrochemical devices, particularly fuel cells and
batteries. A typical proton exchange membrane fuel cell, for
example, has as its principal components a proton-conducting
membrane, anode and cathode electro-catalyst layers with
specific compositions and porosities, and a porous and
conductive gas diffusion layer to allow good access of
hydrogen and oxygen to the electrodes. We propose that this
entire device, termed a membrane-electrode assembly, can be
fabricated by electroprocessing. We have demonstrated to
date that the prototypical proton-conducting membrane,
Nafion, can be electrosprayed and has electrical properties
identical to that of commercial films. We are now developing
electrode compositions for electrospraying, to be shortly
followed by electrospinning of gas diffusion layers.
Attention is also being directed to fabrication of Li
battery components by electroprocessing, including gel
electrolytes and metal oxide cathodes.
3. Microfluidics and Sensors
We have helped to develop a new approach
to 'lab-on-a-chip' microfluidic devices based on 2-D
printing of hydrophilic paths on otherwise hydrophobic
surfaces and bringing two such surface in close proximity
without actual contact. Water will wet the hydrophilic paths
and be drawn along them by capillary action, yet the
sidewalls are in contact with air and thus the water
channels are confined by the fluid's surface tension. An
attractive feature of this approach is that all paths can be
easily printed on inexpensive materials rather than
inscribed as 3-D channels as is the case with conventional
microfluidic devices. Another attribute is that reactive
reagents can be 'spotted' along the paths by printing,
affording a simple means to fabricate complex assay systems.
Our group is also developing impedance-based sensors for
live cell cultures, building on the work on electric
cell-substrate impedance sensing (ECIS) by Giaever and Keese
at RPI. Our focus is sensing in 3-D cell cultures that
better mimic the natural environment of cells and tissues,
and we have developed a system using thin (ca. 2-10 mm) gold
wires in fibrin gels that is the subject of a paper in
preparation. The gold wire diameters are similar to those of
many mammalian axons, and we plan to focus on the notion of
using the wires as artificial axon templates for neural cell
growth, with specific attention toward understanding
biochemical triggers of myelination and demyelination, the
latter being associated with neurodegenerative diseases such
as multiple sclerosis.
Current Activity
Coming soon.
Recent Publications
M. J. Swickrath, S. Shenoy, J. A. Mann, Jr., J. Belcher, R. Kovar and G. E. Wnek, “An Alternative Processing Paradigm for Autonomous Surface Tension-Confined Microfluidic Platforms,” Microfluidics and Nanofluidics, in press.
M. J. Swickrath, J. A. Mann and G. E. Wnek, “Surface-Directed Capillary Flow Systems,” Encyclopedia of Micro- and Nano-Fluidics, in press.
I. G. Loscertales, J. E. Diaz Gomez, M. Lallave, J. M. Rosas, J. Rodriguez-Mirasol, T. Cordero, M. Marquez, S. Shenoy, G. E. Wnek, T. Thorsen, A. Fernandez-Nieves and A. Barrero, “Coaxial Electrospinning for Nanostructured Advanced Materials,” Mater. Res. Soc. Symp. Proc., Vol. 948, B06-01 (2007).
M. C. McManus, E. D. Boland, H. P. Koo, C. P. Barnes, K. J. Pawlowski, G. E. Wnek, D. J. Simpson and G. L. Bowlin, “Mechanical Properties of Electrospun Fibrinogen Structures,” Acta Biomaterialia, 2, 19 (2006).
A. Guiseppi-Elie, S. Brahim, G. E. Wnek and R. H. Baughman, “Carbon Nanotube-Modified Electrodes for the Direct Bioelectrochemistry of Pseudoazurin,” Nanobiotechnology, 1, 83 (2005).
T. Telemeco, C. Ayers, G. L. Bowlin, G. E. Wnek, E. D. Boland, N. Cohen, M. Vaida, D. Tang, C. M. Baumgarten, J. Matthews, and D. G. Simpson, “Regulation of Cellular Infiltration into Tissue Engineering Scaffolds Composed of Submicron Diameter Fibrils Produced by Electrospinning,” Acta Biomaterialia, 1, 377 (2005).
S. L. Shenoy, W. D. Bates and G. E. Wnek, “Correlation Between “Electrospinnability” and Physical Gelation,” Polymer, 46, 8990-9004 (2005).
G. E. Wnek and S. G. Cort, “Product and
Process Design and Delivery: Invention Through to
Innovation,” Proc. ASEE Annual Conference and Exposition,
Portland, OR, June 2005.
O. A. Baturina and G. E. Wnek,
“Characterization of PEM Fuel Cells with Catalyst Layers
Obtained by Electrospraying,” Electrochem. Solid State
Lett., 8, A267 (2005).
S.L. Shenoy, H. L. Frisch, W. D. Bates
and G. E. Wnek, "Role of Chain Entanglements on Fiber
Formation During Electrospinning of Polymer Solutions: Good
Solvent, Non-Specific Polymer-Polymer Interaction Limit," Polymer, 46, 3372 (2005).
D. L. Woerdeman, P. Ye, S. Shenoy, R. S.
Parnas, G. E. Wnek, and O. Trofimova, “Electrospun Fibers
from Wheat Protein: Investigation of the Interplay between
Molecular Structure and the Fluid Dynamics of the
Electrospinning Process,” Biomacromolecules, 6,
707 (2005).
E. D. Boland, K. J. Pawlowski, D. G.
Simpson, G. E. Wnek and G.L. Bowlin. "Electrospinning
Collagens and Elastin: Preliminary Vascular Tissue
Engineering." Frontiers in Biosciences, 9,
1422 (2004).
E. H. Sanders, K. A. McGrady, G. E. Wnek,
C. A. Edmonson, J. M. Mueller, J. J. Fontanella, S. Suarez
and S G. Greenbaum, "Characterization of Electrosprayed
Nafion Films," J. Power Sources, 129, 55
(2004).
E. H. Sanders, R. Kleofkorn, G. L. Bowlin,
D. G. Simpson and G. E. Wnek, “Two-Phase Electrospinning
from a Single Electrified Jet: Microencapsulation of Aqueous
Reservoirs in Poly(Ethylene-co-Vinyl Acetate) Fibers,” Macromolecules, 36, 3803 (2003).
E.-R. Kenawy, J. M. Layman, J. R.
Watkins, G. L. Bowlin, J. A. Matthews, D. G. Simpson and G.
E. Wnek, “Electrospinning of Poly(Ethylene-co-Vinyl Alcohol)
Fibers,” Biomaterials, 24, 907-913 (2003).
L. Yao, T. W. Haas, A. Guiseppi-Elie, G.
L. Bowlin, D. G. Simpson, and G. E. Wnek, “Electrospinning
and Stabilization of Fully Hydrolyzed Poly(vinyl alcohol)
Fibers,” Chem. Mater, 15, 1860 (2003).
G. E. Wnek, M. E. Carr, D. G. Simpson and
G. L. Bowlin, “Electrospinning of Nanofiber Fibrinogen
Structures,” Nano Lett., 3, 213-216 (2003).
Awards
John W. Hyatt Award (benefit to society), Society of Plastics Engineers, 2007
Kern Faculty Fellow, NCIIA/Kern Entrepreneurship Education Network, 2006-07
NASA Lecturer, 64th Frontiers in
Chemistry Symposium, Case Western Reserve University, 2004
Sidney Negus Memorial Lecturer, Virginia
Academy of Sciences, 1999
1996 Eastern New York Intellectual
Property Law Association Inventor of the Year Award (for
U.S. patent 5,468,574) |
