Browsing by Subject "nanoparticles"

Now showing 1 - 7 of 7
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    Controlled short time large scale synthesis of magnetic cobalt nanoparticles on carbon nanotubes by flash annealing
    (AIP, 2020) Mosey, Aaron; Yue, Lanping; Gaire, Babu; Ryu, Jong Eun; Cheng, Ruihua; Physics, School of Science
    Nanopatterned arrays of discrete cobalt nanostructures showing characteristic parameter-dependent sizes are formed from continuous thin films on a carbon nanotube substrate using millisecond pulsed intense UV light. The nanoparticles exhibit ferromagnetic behavior with magnetic remanence and coercivity depending on the particle size. The end-state particle size is shown to be a function of initial thin film thickness and excitation energy and is therefore tunable. The evolutionary process from continuous thin films to a discrete morphology is thermodynamically driven by the large surface energy difference between metastable thin films and the underlying carbon nanotube substrate. Evidence of the Danielson model of the dewetting process is observed. These arrays can find applications as platforms for the self-assembly of magnetically susceptible materials, such as iron or nickel nanostructures, into a conduction matrix for applications in energy extraction from a latent heat storage device.
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    Effect of carbon nanotubes on transepithelial resistance in barrier epithelial cells
    (Office of the Vice Chancellor for Research, 2012-04-13) Lewis, Shanta; Blazer-Yost, Bonnie L.; Petrache, Horia I.; Roark, Torri
    The burgeoning of the nanotechnology industry has revolutionized engineering, medicine and the fashion industry amongst many other technologies. The arrays of products that are synthesized from nanomaterials include high definition TV and computer screens, artificial organs, as well as antibacterial food containers. With these novel applications there is a paralleled concern of the negative implications of nano-material contamination in our environment and food chains. We are interested in carbon nanotubes because they are the most abundantly occurring nanoparticles that are found in the workplace. We have recently conducted studies in barrier epithelial cells to show that long single-wall and multi-wall carbon nanotubes (CNTs) caused a decrease in the transepithelial electrical resistance, a measure of the barrier function ,of renal principal cells at very low concentrations (0.4 ng/cm2- 4 g/cm2). These results suggested that nanoparticles may also cause an effect on other barrier epithelial cells such as those lining the human digestive and respiratory tracks. After 48 hours of CNT exposure, to airway and colon cell lines, Calu-3 and t84 respectively, the calculated resistances were approximately half of the control monolayers’, indicating that the barrier function of the tissue had been compromised, while the cellular monolayer remained intact. We sought to determine the mechanism of action of the nanoparticles, by investigating the interaction of CNTs with model lipid membranes using a bilayer clamp amplifier. Measurements showed that the presence of nanoparticles caused transient disruptions in lipid membranes made of phosphatidylcholine lipids. Nanotubes also caused transient interruptions in the current allowed by the ion channel reporter (gramicidin A). These results began to elucidate the mode of action of the particles and indicated that it is important to develop a complete understanding of how nanoparticles interact with cells if we are to safeguard against changes that these materials will cause in vivo.
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    Effects of Carbon Nanotubes in Barrier Epithelial Cells via Effects on Lipid Bilayers
    (Office of the Vice Chancellor for Research, 2013-04-05) Lewis, Shanta; Petrache, Horia I.; Blazer-Yost, Bonnie L.; Witzmann, Frank
    Carbon nanotubes (CNTs) are one of many nanoparticles (NP) which are being developed as part of the burgeoning nanotechnology. The tubes have similar physical properties to known toxic materials, such as asbestos; yet there is a lack of evidence showing that they may be hazardous to humans, specifically to our barrier epithelial cells. We measured the effects of CNTs on human airway epithelial cells (Calu-3 cell line) using electrophysiology. This is a technique which measures transepithelial electrical resistance (TEER), a measure of monolayer integrity; and short circuit current (SCC) a measure of net ion transport across the cell. Exposed cells showed significant decreases in TEER when incubated for 48 hours with physiologically relevant concentrations of 4μg/cm2 - 0.4ng/cm2 of multi-wall (MW) and 4μg/cm2 - 0.04ng/cm2 single-wall (SW) CNT. TEER is a measure of barrier function which is important in cells that maintain separate compartments in the body. The impaired barrier function, despite sustained cell viability, led us to investigate the mechanism by which the CNT were interacting with the cell when applied topically. Model lipid membranes connected to an ion channel amplifier, Planar Bilayer Workstation (BLM), were used. Membranes were formed using the neutral diphytanoylphosphatidylcholine (DPhPC) and negatively charged diphytanoyl phosphatidylserine (DPhPS) lipids. CNTs caused random, transient currents ranging from 0pA to 6479pA to traverse the membrane. In the presence of Gramicidin A, an ion channel reporter protein, the tubes induced increased gramicidin channel formation in the membrane to saturation level and then membrane lysis. This CNT- lipid interaction indicated that short MWCNTs permits unregulated ion movement across the lipid membrane. Disruption in the selective permeability of the plasmalemma may impact the tissue’s barrier function.
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    High sensitivity nanotechnology gas sensing device
    (2016-12) Tanu, Tanu; Rizkalla, Maher. E.
    The nanotechnology materials have been used for high sensitivity sensing devices due to their ability to alter their properties in response to the environmental parameters such as temperature, pressure, gas, electromagnetic, and chemicals. The features of employing nanoparticles on top of graphene thin film have driven the hypothesis of achieving high sensing nanotechnology devices. This study demonstrates a novel approach for designing a low noise nanoparticle based gas sensing device with internet of things (IoT) capability. The system is capable of minimizing cross-talk between multiple channels of amplifiers arranged on one chip using guard rings. Graphene mono-layer is utilized as sensing material with the sensitivity catalyzed by addition of gold nano-particles on its surface. The signal from the sensing unit is received by an offset cancellation amplifying system using a system on chip (SoC) approach. IoT capability of the sensing device is developed using FRDM K64f micro-controller board which sends messages on IoT platform when a gas is sensed. The message is received by an application created and sent as an email or message to the user. This study details the mathematical models of the graphene based gas sensing devices, and the interface circuitry that drives the differential potentials, resulting from the sensing unit. The study presents the simulation and practical model of the device, detailing the design approach of the processing unit within the SoC system and wireless implementation of it. The sensing device was capable of sensing gas concentration from 5% to 100% using both the resistive and capacitive based models. The I-V characteristics of the FET sensing device was in agreeable with the other models. The SoC processing unit was designed using cadence tools, and simulation results showed very high CMRR that enable the amplifier to sense a very low signal received from the gas sensors. The cross talk noise was reduced by surrounding guard rings around the amplifier circuits. The layout was accomplished with 45nm technology and simulation showed an offset voltage of 17μV.
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    Influenza Group 2 HA Stem-Only Nanoparticles Induce Heterotypic Immune Response
    (2017-08) Asdell, Stephanie M.; Moin, Syed M.; Corbett, Kizzmekia; Boyington, Jeffrey; Graham, Barney S.
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    Skin Regeneration Using Dermal Substrates that Contain Autologous Cells and Silver Nanoparticles to Promote Antibacterial Activity: In Vitro Studies
    (AMSUS, 2017-03) Zieger, Michael A. J.; Ochoa, Manuel; Rahimi, Rahim; Campana, Gonzalo; Tholpady, Sunil; Ziaie, Babak; Sood, Rajiv; Surgery, School of Medicine
    We hypothesized that the addition of silver nanoparticles (AgNP) to a dermal substrate would impart antibacterial properties without inhibiting the proliferation of contained cells. Our in vitro model was based on the commercial substrate, Integra. The substrate was prepared by simple immersion into 0 to 1% suspension of AgNP (75 or 200 nm diameter) followed by rinsing for 20 minutes and sterilization under an ultraviolet C lamp. A total of 107 human adipose stem cells per cubic centimeter were injected and after 1 hour, 6 × 105 keratinocytes/cm2 were seeded and cultured for up to 14 days. Constructs were evaluated using a metabolic assay (WST-1), and hematoxylin and eosin and immunoperoxidase staining. Bactericidal activity was measured using a log reduction assay against bacteria that are prevalent in burns. The presence of AgNP did not significantly change the metabolic activity of constructs after 14 days of culture, and the distribution of cells within the substrate was unchanged from the controls that did not have AgNP. Antibacterial activity of Integra containing AgNP (75 nm diameter) was concentration dependent. In conclusion, the addition of AgNP to the dermal substrate suppressed bacterial growth but did not significantly affect cell proliferation, and may represent an important property to incorporate into a future clinical skin regeneration system.
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    SYNTHESIS AND FUNCTIONALIZATION OF CIGS NANOPARTICLES FOR LBL DEPOSITION
    (Office of the Vice Chancellor for Research, 2012-04-13) Canner, Mark; Cambridge, Jason; Agarwal, Mangilal; Shrestha, Sudhir; Varahramyan, Kody
    Copper Indium Gallium Diselenide (CIGS) solar cells have been used widely in thin film solar cells due to their high attainable efficien-cy and tunable band gap. The cost of solar cell manufacturing needs to be further reduced to make CIGS solar cells economically viable. The main objective of this research is to repeatedly and accurately synthe-size CIGS nanoparticles in a desired ratio to allow for an efficient band gap and dispersion in an aqueous solution for Layer-by-Layer (LbL) nanoassembly. CIGS nanoparticles have been synthesized by arrested precipitation in Oleylamine solution. The particles were purified utiliz-ing chloroform, ethanol, and water via centrifugation. The purified na-noparticles were down to a size of 15 nm with average size of 60 nm. A ligand exchange was performed to remove the capping agent, Oleylamine, and replace it with 11-mercaptoundecanoic acid, a thiol ligand. The thiol ligand used had charged functional groups resulting in the functionalized particles with expected high negative zeta potential for stable dispersion. Lastly, the nanoparticles were analyzed through the utilization of X-ray diffractive spectroscopy (XRD), transmittance spectroscopy, energy-dispersive x-ray spectroscopy (EDS) and a scan-ning electron microscope (SEM). Using the oppositely charged disper-sion in aqueous solutions, multiple size-controlled layers of CIGS can be obtained using Layer-by-Layer nanoassembly, creating a solar cell. The synthesis, characterization and functionalization results will be presented in the poster.