4.E.1 Seed Funding and Emerging Areas
For C-SPIN to remain topical, we must respond to opportunities within and outside of the Center.
To this end, about 10% of the budget is set aside for seed funding. New areas to pursue will be
determined annually by the Executive Committee (EC) from submissions by C-SPIN or other UA/OU
faculty based on the quality of the proposal and overlap with Center interests. Seed areas will target
higher risk projects and emerging areas of interdisciplinary research; however, industrial outreach or
educational ventures will also be considered. Seeds by junior faculty or that establish links with other
disciplines have priority. The graduation of previous seeds to external funding is discussed in section 4B.
Seed proposals will be solicited every twelve months but accepted at any time. The proposals
themselves will be in the form of a two-page white paper which addresses the following questions: What
is the overall description of the project, what are the expected measurable outcomes, and how will this
project actively address emerging science and engineering issues in nanoscience? Who are the members
of your interdisciplinary team and how will they actively contribute to this grant? How will this seed
grant leverage support for continued research after the seed period? What is the timeline for the
proposed research? And, what is the proposed budget request?
Seed proposals will be reviewed by the EC and appropriate members of the External Review
Board. The maximum duration of a Seed will be 2-3 years. After that, the Seed should have obtained
other funding and/or junior faculty should have been incorporated into C-SPIN’s existing IRGs.
Below we discuss Seed candidates for the first two years of the proposed CEMRI. They were
chosen not only on merit, but also on their potential to jointly form a new IRG in future competitions.
Nano-Textured Surfaces for Biological Applications
(UA) M. Zou, D.K. Roper, J. Li; (OU) M.B. Johnson, D.W. Schmidtke, B. Starly; 2 graduate students
Focus: To develop nanostructured surfaces for biological applications including: biosensors, biomimetic
surfaces, and biologically active/inactive surfaces.
Motivation: The interaction of biological systems with engineered surfaces requires the control and
characterization of complex surfaces on the micro- through nano-scales, and ways to investigate the
interactions of these surfaces with simplified but realistic biological systems. Breakthroughs in this highly
interdisciplinary area will be important throughout the life and medical sciences.
Proposed Research: The specific areas of investigation include: using 3D control of surfaces to improve
the sensitivity and selectivity of biosensors; fabricating nanoelectrode arrays; patterning micron- through
nano-sized 3D structures of protein ligands to mimic the structure of vascular walls to understand blood
cell (e.g., platelets, leukocytes) interactions with vascular walls during inflammation and thrombosis; and
finally, controlling surface topography to enhance or inhibit their interactions with biological systems. E01
Biosensors: Amperometric biosensors are being developed for applications such as point-of-care
diagnostics, remote sensors in environmental monitoring, and warning systems against
chemical/biological warfare agents. For such biosensors to be useful, they must be portable, simple to
operate, and make measurements in a natural environment. Thus it is necessary to miniaturize these
sensors, which necessitates that the sensor exhibits high sensitivity and produces a signal that is
measurable with low-cost portable electronics. Two ways to increase the sensor output are to increase the
sensor surface areaE02 and the enzyme loading.E03 Both of these can be achieved by expanding the sensor
surface to into 3D structures. The techniques involved to achieve this architecture include: near-field
direct writing of electrospun poly(3,4-ethylenedioxythiophene) (PEDOT)
nanofibers (Starly); layer-by-layer deposition of redox enzymes and redox
polymers (Schmidtke)E04,5 as coatings to these nanofibers or 2D layers between
nanofibers; incorporation of single- E04-6 and multi-walled carbon nanotubes
(Schmidtke). Figure E1-1 shows a schematic of such a 3D structure. Additionally
we will also fabricate gold nanoelectrode arrays (NEAs, ordered nanoelectrode
distribution) and nanoelectrode ensembles (NEEs, random nanoelectrode
E1-1. Biosensor in
distribution) by e-beam (Johnson, Roper) and/or particle lithography (Roper, Fig.
cross-section fabricated
Schmidtke). Benefits of nanoelectrodes over macro-sized electrodes include: using electrostatic layerenhanced mass transport, convection-independent responses, high signal-to-noise by-layer deposition.
4.E.1 1 of 3
ratios (S/N), fast response times; and lower-detection limits.E07 Techniques used to characterize these
structures include: profilometery (Johnson), liquid/air AFM, liquid/air ellipsometry (Johnson) and FESEM. Sensor response (Schmidtke) will be measured by amperometry, cyclic voltammetry (CV) and
electrochemical impedance spectroscopy (EIS). In addition to sensitivity requirements, the mechanical
properties of these layers must be sufficient to withstand the shear stress of a fast flowing fluid or the
movement of a contacting biological tissue.E08 We will use air and liquid AFM (Johnson) and nanoindenting (Zou) to characterize the frictional and adhesive characteristics of these films.
Biomimetics: Leukocyte adhesion to blood vessel walls plays a crucial role in a number of biological
processes such as inflammation and thrombosis.E09 We will develop nanoscale protein patterning methods
to mimic the vascular environment to elucidate the role of nanoscale ligand presentation in regulating
leukocyte adhesion and rolling under flow. The techniques used to pattern the surfaces will include: topdown e-beam lithography (Johnson), as well as inexpensive bottom-up bead lithography
(Schmidtke).E10,11 Fabrication will involve a wide range of deposition and wet- and dry-etching
techniques, while characterization will involve AFM, ellipsometry and FE-SEM. Nano-indenting (Zou)
and AFM in liquid will be used to directly investigate the adhesion properties of cells (attached to
nanondenter and AFM tips) with the protein-patterned surfaces.
Bio active/inactive Surfaces: The bioactivity of surfaces is dominated by their wetting characteristics.E012
In this thrust we develop superhydrophobic surface for biocidal applications and the wetting
characteristics of surfaces with ordered porous surfaces whose pores can be used for the slow release of
drugs/proteins to promote healing.
Transport Theory in Graphene &Carbon Nanotube Composites
(OU) K. Mullen, A. Striolo, D. Papavassilou; (UA) D.K. Roper; 1 graduate student
Focus: Modeling heat transport in composites of graphene or carbon nanotubes in a polymer matrix.
Motivation: The quest for high thermal conductivity (TC) materials has lead to nano-composites
incorporating small amounts of nanoparticles with excellent thermal conductivity, such as carbon
nanotubesE13 (CNTs) and graphene nano-ribbons (GNRs),E14 in a
polymeric matrix with poor thermal conductivity. These fail due
to the “Kapitza resistance” at the boundary of two dissimilar
materials which produces a temperature drop across the interface
proportional to the heat flux.E15,16 The effect is large when the two
materials have a large difference in elasticity. When this
resistance will be minimized, heavy metallic components used in
car radiators and other heat exchangers will be replaced with light
advanced composites.
Proposed Research: Chemical functionalization of GNRs and
CNTs would allow a transitional region that would effectively
match phonon modes inside and outside the nano-scale filler. We
plan to address the theory of this problem on three levels:
Optimizing Side Chains: On the smallest scale we plan to study
the side chains that optimally couple the filler to the matrix.
Shown in Fig. E1-2 is a model of a carbon nanotube with simple
alkanes attached to either end. By studying the low energy normal Fig. E1-2:
Top: CNT
modes of this system we can learn how to optimize their functionalized
participation ratioE17,18, Modes with a large participation ratio with alkane end chains;
efficiently couple vibrations outside the CNT to the interior, Middle: a “poor” mode (low
where they propagate at high velocity. Continuum models indicate participation ratio) -interior motion not
that a large linear mass density can improve phonon coupling.E19 coupled to the exterior side chains;
We will investigate if this can be achieved by branched organic Bottom: a “good” mode (large
side chains or using metallo-organic chains calculating the normal participation ratio) -side chains couple
modes of the system and using a Langevin formalism, directly to interior motion, allowing CNT to
transport energy efficiently.
calculating the thermal conductivity of the system.
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Optimizing the distribution of functionalizing chains: The addition of side chains to GNRs or CNTs may
severely disrupt the otherwise excellent conducting properties of the pristine material. Random
perturbations to 1D systems are known to cause localization of propagating waves. Thus there is a tradeoff between improving phonon transport into the filler by adding side chains and maintaining excellent
transport through the filler. Wider GNRs will be less affected by such perturbations, but they might be
stiffer. We will study the localization of modes both by classical analysis and using localization theory.
Optimizing the distribution of functionalized fillers within the composite: Given a CNT with good thermal
coupling at its ends (as in Fig. E1-2), we must optimize the composite thermal conductivity. A Monte
Carlo-based algorithm, developed in house, will be employed study the thermal transport in CNT-based
nanocomposites. The results will be useful for the necessary comparison to and guidance for experimental
practices. Similar procedures will be adopted to optimize GS-based nanocomposites.
Hierarchical Plasmonic Assemblies for Enhanced Upconversion Fluorescence
(OU) L.A. Bumm, R.L. Halterman, Y.T. Yip; (UA) J. Chen, C. Heyes, D.K. Roper; 2 graduate students
Focus: Using solution growth, selective surface chemistries, nano- fabrication and characterization
techniques to develop plasmonic assemblies to enhance the conversion of two photons into a single
photon of higher frequency (upconversion).
Motivation: Unlike two-photon molecular fluorescence, which requires intense optical fields,
upconversion fluorophore nanoparticles (UFNs) require only modest intensities (~102 W/cm2),E20,21 and
their combination with plasmonic systems promises to further reduce the required excitation intensity.
Indeed enhancement has already been demonstrated experimentallyE22 and studied theoretically.E23 The
key is the controlled placement of UFNs near a plasmonic structure to enhance excitation and/or
emission. The NIR excitation also allows better utilization of the optical range of both Ag and Au
plasmonic systems. UFNs have applications in biological imaging, in security tags and in video displays.
Proposed Research: We plan to control the placement of UFNs in the plasmon near-field of the
assembly and to study the plasmon resonances, fluorescence yield and lifetime of the resulting structure.
Our specific areas of interest include: controlled placement of fluorophores on plasmonic nanoparticles
(rods and core-shell), in plasmonic nanoparticle dimers (homo and hetero dimers), and in plasmonic
nanoparticle arrays; selective enhancement of upconversion fluorescence excitation and emission, and
plasmon mediated FRET to additional conventional fluorphores. UFNs, grown by known methods (Chen,
Halterman)E20,22 will be used in this work. Gold nanorods exhibit a long wavelength plasmon resonance
and shorter wavelength transverse and multimode longitudinal resonances,E24 which can be tuned by
varying the length and diameter of the rods. Shape selective surface chemistryE25 (Halterman) will be used
to target attachment of the UFN to the end or side of the rod. The longitudinal plasmon resonance will be
tuned to the excitation wavelength, while the transverse resonance will be tuned to the desired emission
wavelength. These and other assemblies will be characterized by single nanoparticle scattering (Bumm)
and fluorescence (Heyes, Yip) guided by computational modeling (Roper).E26 UFNs will be combined
with tuned core-shell NPs, cubes, and other shaped NPs (Chen)E27 and will be explored and characterized
(Bumm, Heyes, Yip). Nanoparticle dimers (Chen, Halterman) can be used to concentrate the energy on an
NC bound in the gap. For example end-to-end nanorod dimers show
intense fields in the gap which will be utilized to enhance the UFN
emission.E28 Asymmetrical dimers (size, shape, and composition—Au,
Ag, Ag/Au alloys) will have symmetric and asymmetric modes that can
be tuned to the UFN excitation and emission. NP arrays (Roper) will be
fabricated by EBL, NSL, and NIL will increase the plasmon
enhancements by superposition of coherent scattered photons and to
position the UFNs in enhanced field regions.E29 A molecular “resist”
activated by nonlinear photochemistry (Halterman) will directly use the
enhanced fieldsE30 in the NP array to target the attachment of NCs to the Fig. E1-3. Diagrams of several
example plasmonic assemblies.
active regions, e.g. photo-deprotection of amines.E31
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