Vanderbilt Institute of Nanoscale Science and Engineering

Nashville, TN, United States

Vanderbilt Institute of Nanoscale Science and Engineering

Nashville, TN, United States
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Douglas A.,Vanderbilt University | Carter R.,Vanderbilt University | Muralidharan N.,Vanderbilt University | Oakes L.,Vanderbilt University | And 2 more authors.
Carbon | Year: 2017

Until now, research efforts focused on electrochemical conversion of carbon dioxide into stable carbon-based materials have been limited by poor understanding of catalytic effects occurring at surfaces. Here, we demonstrate the capability to simultaneously use atomic layer deposition (ALD), electrode composition control, and current density as a means to direct the formation of iron-based catalysts and grow highly crystalline multi-walled carbon nanotubes at high yields (99%) and with controlled average diameters of 27.5 nm from ambient carbon dioxide captured and dissolved in molten carbonate electrolytes. ALD of passive alumina coatings on a Ni anode prevents electrode corrosion processes and adverse deposition of Ni on the cathode that results in increased CNT diameters, lower CNT quality, and non-CNT products. On the cathode side where CNT growth occurs, our results elucidate the fine balance of iron catalyst accessibility from the cathode interior and the surface chemical properties in order to achieve high yield and high quality CNT growth. Our work provides an intersection between decades of research understanding on catalytic gas-phase growth of CNT materials and the ability to leverage these ideas to sustainably capture ambient carbon dioxide and produce functional CNT materials. © 2017 Elsevier Ltd


Yu S.S.,Vanderbilt Institute of Nanoscale Science and Engineering | Zachman A.L.,Vanderbilt Institute of Nanoscale Science and Engineering | Perrien D.S.,Vanderbilt University | Hofmeister L.H.,Vanderbilt Institute of Nanoscale Science and Engineering | And 3 more authors.
Biomacromolecules | Year: 2011

Chronic inflammation-mediated oxidative stress is a common mechanism of implant rejection and failure. Therefore, polymer scaffolds that can degrade slowly in response to this environment may provide a viable platform for implant site-specific, sustained release of immunomodulatory agents over a long time period. In this work, proline oligomers of varying lengths (Pn) were synthesized and exposed to oxidative environments, and their accelerated degradation under oxidative conditions was verified via high performance liquid chromatography and gel permeation chromatography. Next, diblock copolymers of poly(ethylene glycol) (PEG) and poly(e-caprolactone) (PCL) were carboxylated to form 100 kDa terpolymers of 4%PEG- 86%PCL-10%cPCL (cPCL = poly(carboxyl-e-caprolactone); i% indicates molar ratio). The polymers were then cross-linked with biaminated PEG-Pn-PEG chains, where Pn indicates the length of the proline oligomer flanked by PEG chains. Salt-leaching of the polymeric matrices created scaffolds of macroporous and microporous architecture, as observed by scanning electron microscopy. The degradation of scaffolds was accelerated under oxidative conditions, as evidenced by mass loss and differential scanning calorimetry measurements. Immortalized murine bonemarrow- derived macrophages were then seeded on the scaffolds and activated through the addition ofγinterferon and lipopolysaccharide throughout the 9-day study period. This treatment promoted the release of H 2O 2 by the macrophages and the degradation of proline-containing scaffolds compared to the control scaffolds. The accelerated degradation was evidenced by increased scaffold porosity, as visualized through scanning electron microscopy and X-ray microtomography imaging. The current study provides insight into the development of scaffolds that respond to oxidative environments through gradual degradation for the controlled release of therapeutics targeted to diseases that feature chronic inflammation and oxidative stress. © 2011 American Chemical Society.


Yu S.S.,Vanderbilt University | Yu S.S.,Vanderbilt Institute of Nanoscale Science and Engineering | Lau C.M.,Vanderbilt University | Thomas S.N.,Ecole Polytechnique Federale de Lausanne | And 7 more authors.
International Journal of Nanomedicine | Year: 2012

The assessment of macrophage response to nanoparticles is a central component in the evaluation of new nanoparticle designs for future in vivo application. This work investigates which feature, nanoparticle size or charge, is more predictive of non-specific uptake of nanoparticles by macrophages. This was investigated by synthesizing a library of polymer-coated iron oxide micelles, spanning a range of 30-100 nm in diameter and -23 mV to +9 mV, and measuring internalization into macrophages in vitro. Nanoparticle size and charge both contributed towards non-specific uptake, but within the ranges investigated, size appears to be a more dominant predictor of uptake. Based on these results, a protease-responsive nanoparticle was synthesized, displaying a matrix metalloproteinase-9 (MMP-9)-cleavable polymeric corona. These nanoparticles are able to respond to MMP-9 activity through the shedding of 10-20 nm of hydrodynamic diameter. This MMP-9-triggered decrease in nanoparticle size also led to up to a six-fold decrease in nanoparticle internalization by macrophages and is observable by T2-weighted magnetic resonance imaging. These findings guide the design of imaging or therapeutic nanoparticles for in vivo targeting of macrophage activity in pathologic states. © 2012 Yu et al, publisher and licensee Dove Medical Press Ltd.


Gaur G.,Vanderbilt University | Koktysh D.S.,Vanderbilt Institute of Nanoscale Science and Engineering | Weiss S.M.,Vanderbilt University
Advanced Functional Materials | Year: 2013

Highly sensitive dual-mode labeled detection of biotin in well-characterized porous silicon (PSi) films using colloidal quantum dots (QDs) as signal amplifiers are demonstrated. Optimization of the PSi platform for targeted QD infiltration and immobilization is carried out by characterizing and tuning the porosity, film depth, and pore size. Binding events of target QD-biotin conjugates with streptavidin probes immobilized on the pore walls are monitored by reflective interferometric spectroscopy and fluorescence measurements. QD labeling of the target biotin molecules enables detection based on a distinct fluorescent signal as well as a greater than 5-fold enhancement in the measured spectral reflectance fringe shift and a nearly three order of magnitude improvement in the detection limit for only 6% surface area coverage of QDs inside the porous matrix. Utilizing the QD signal amplifiers, an exceptional biotin detection limit of ≈6 fg mm-2 is demonstrated with sub-fg mm-2 detection limits achievable. White light reflective interferometric spectroscopy and fluorescence measurements are used to implement a novel dual-mode optical porous silicon biosensor. Quantum dots act as signal amplifiers resulting in over an order of magnitude increase in sensor response and providing a secondary means of biomolecule-specific recognition through their distinct fluorescence spectra. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


McClure R.,Vanderbilt University | Yanagisawa D.,Shiga University of Medical Science | Stec D.,Vanderbilt University | Abdollahian D.,Vanderbilt University | And 10 more authors.
Journal of Alzheimer's Disease | Year: 2015

Curcumin is a promising compound that can be used as a theranostic agent to aid research in Alzheimer's disease. Beyond its ability to bind to amyloid plaques, the compound can also cross the blood-brain barrier. Presently, curcumin can be applied only to animal models, as the formulation needed for iv injection renders it unfit for human use. Here, we describe a novel technique to aerosolize a curcumin derivative, FMeC1, and facilitate its safe delivery to the brain. Aside from the translational applicability of this approach, a study in the 5XFAD mouse model suggested that inhalation exposure to an aerosolized FMeC1 modestly improved the distribution of the compound in the brain. Additionally, immunohistochemistry data confirms that following aerosol delivery, FMeC1 binds amyloid plaques expressed in the hippocampal areas and cortex. © 2015 - IOS Press and the authors. All rights reserved.


Harkness K.M.,Vanderbilt University | Harkness K.M.,Vanderbilt Institute of Chemical Biology | Harkness K.M.,Vanderbilt Institute for Integrative Biosystems Research and Education | Harkness K.M.,Vanderbilt Institute of Nanoscale Science and Engineering | And 7 more authors.
Analyst | Year: 2010

Thiolate-protected gold nanoparticles (AuNPs) are a highly versatile nanomaterial, with wide-ranging physical properties dependent upon the protecting thiolate ligands and gold core size. These nanoparticles serve as a scaffold for a diverse and rapidly increasing number of applications, extending from molecular electronics to vaccine development. Key to the development of such applications is the ability to quickly and precisely characterize synthesized AuNPs. While a unique set of challenges have inhibited the potential of mass spectrometry in this area, recent improvements have made mass spectrometry a dominant technique in the characterization of small AuNPs, specifically those with discrete sizes and structures referred to as monolayer-protected gold clusters (MPCs). Additionally, the unique fragmentation data from mass spectrometry enables the characterization of the protecting monolayer on larger AuNPs. The development of mass spectrometry techniques for AuNP characterization has begun to reveal interesting new areas of research. This report is a discussion of the historical challenges in this field, the emerging techniques which aim to meet those challenges, and the future role of mass spectrometry in the growing field of thiolate-protected AuNPs. © 2010 The Royal Society of Chemistry.


Kobukai S.,Vanderbilt University | Baheza R.,Vanderbilt University | Cobb J.G.,Vanderbilt University | Virostko J.,Vanderbilt University | And 7 more authors.
Magnetic Resonance in Medicine | Year: 2010

We report the development of superparamagnetic iron oxide (SPIOs) nanoparticles and investigate the migration of SPIOlabeled dendritic cells (DCs) in a syngeneic mouse model using magnetic resonance (MR) imaging. The size of the dextran- coated SPIO is roughly 30 nm, and the DCs are capable of independent uptake of these particles, although not at levels comparable to particle uptake in the presence of a transfecting reagent. On average, with the assistance of polylysine, the particles were efficiently delivered inside DCs within one hour of incubation. The SPIO particles occupy approximately 0.35% of cell surface and are equivalent to 34.6 pg of iron per cell. In vivo imaging demonstrated that the labeled cells migrated from the injection site in the footpad to the corresponding popliteal lymph node. The homing of labeled cells in the lymph nodes resulted in a signal drop of up to 79%. Furthermore, labeling DCs with SPIO particles did not compromise cell function, we demonstrated that SPIO-enhanced MR imaging can be used to track the migration of DCs effectively in vivo. © 2010 Wiley-Liss, Inc.


Douglas A.,Vanderbilt University | Carter R.,Vanderbilt University | Oakes L.,Vanderbilt University | Share K.,Vanderbilt University | And 3 more authors.
ACS Nano | Year: 2015

Nanocrystals with quantum-confined length scales are often considered impractical for metal-ion battery electrodes due to the dominance of solid-electrolyte interphase (SEI) layer effects on the measured storage properties. Here we demonstrate that ultrafine sizes (μ4.5 nm, average) of iron pyrite, or FeS2, nanoparticles are advantageous to sustain reversible conversion reactions in sodium ion and lithium ion batteries. This is attributed to a nanoparticle size comparable to or smaller than the diffusion length of Fe during cation exchange, yielding thermodynamically reversible nanodomains of converted Fe metal and NaxS or LixS conversion products. This is compared to bulk-like electrode materials, where kinetic and thermodynamic limitations of surface-nucleated conversion products inhibit successive conversion cycles. Reversible capacities over 500 and 600 mAh/g for sodium and lithium storage are observed for ultrafine nanoparticles, with improved cycling and rate capability. Unlike alloying or intercalation processes, where SEI effects limit the performance of ultrafine nanoparticles, our work highlights the benefit of quantum dot length-scale nanocrystal electrodes for nanoscale metal sulfide compounds that store energy through chemical conversion reactions. © 2015 American Chemical Society.


Douglas A.,Vanderbilt University | Muralidharan N.,Vanderbilt University | Carter R.,Vanderbilt University | Share K.,Vanderbilt University | And 2 more authors.
Nanoscale | Year: 2016

Here we demonstrate the first on-chip silicon-integrated rechargeable transient power source based on atomic layer deposition (ALD) coating of vanadium oxide (VOx) into porous silicon. A stable specific capacitance above 20 F g-1 is achieved until the device is triggered with alkaline solutions. Due to the rational design of the active VOx coating enabled by ALD, transience occurs through a rapid disabling step that occurs within seconds, followed by full dissolution of all active materials within 30 minutes of the initial trigger. This work demonstrates how engineered materials for energy storage can provide a basis for next-generation transient systems and highlights porous silicon as a versatile scaffold to integrate transient energy storage into transient electronics. © 2016 The Royal Society of Chemistry.


PubMed | Vanderbilt Institute of Nanoscale Science and Engineering
Type: Journal Article | Journal: ACS nano | Year: 2015

Nanocrystals with quantum-confined length scales are often considered impractical for metal-ion battery electrodes due to the dominance of solid-electrolyte interphase (SEI) layer effects on the measured storage properties. Here we demonstrate that ultrafine sizes (4.5 nm, average) of iron pyrite, or FeS2, nanoparticles are advantageous to sustain reversible conversion reactions in sodium ion and lithium ion batteries. This is attributed to a nanoparticle size comparable to or smaller than the diffusion length of Fe during cation exchange, yielding thermodynamically reversible nanodomains of converted Fe metal and NaxS or LixS conversion products. This is compared to bulk-like electrode materials, where kinetic and thermodynamic limitations of surface-nucleated conversion products inhibit successive conversion cycles. Reversible capacities over 500 and 600 mAh/g for sodium and lithium storage are observed for ultrafine nanoparticles, with improved cycling and rate capability. Unlike alloying or intercalation processes, where SEI effects limit the performance of ultrafine nanoparticles, our work highlights the benefit of quantum dot length-scale nanocrystal electrodes for nanoscale metal sulfide compounds that store energy through chemical conversion reactions.

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