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Title: Theoretical and Computational Studies of the electronic, Structural, Vibrational, and Thermodynamic Properties of Transition Metal Nanoparticles.
Creator: Sadatshafaie, Ghazal, Rahman, Talat, Stolbov, Sergey, Ishigami, Masa, Masunov, Artem, University of Central Florida
Abstract / Description: The main objective of this dissertation is to provide better understanding of the atomic configurations, electronic structure, vibrational properties, and thermodynamics of transition metal nanoparticles and evaluate the intrinsic (i.e. size and shape) and extrinsic (i.e. ligands, adsorbates, and support) effects on the aforementioned properties through a simulational approach. The presented research provides insight into better understanding of the morphological changes of the nanoparticles...
Show moreThe main objective of this dissertation is to provide better understanding of the atomic configurations, electronic structure, vibrational properties, and thermodynamics of transition metal nanoparticles and evaluate the intrinsic (i.e. size and shape) and extrinsic (i.e. ligands, adsorbates, and support) effects on the aforementioned properties through a simulational approach. The presented research provides insight into better understanding of the morphological changes of the nanoparticles that are brought about by the intrinsic factors as well as the extrinsic ones. The preference of certain ligands to stabilize specific sizes of nanoparticles is investigated. The intrinsic and extrinsic effects on the electronic structure of the nanoparticles are presented. The physical and chemical properties of the nanoparticles are evaluated through better understanding of the above effects on the experimentally observed properties as well as the applied techniques. The unexpected experimental results are tested and interpreted by deconvolution of the affecting factors. The application of Debye model to nanoparticles is tested and its shortcomings at nanoscale are discussed. Predictions which can provide insight into intelligent choice of candidates to cater to certain properties are provided. The results of this thesis can be used in the future in design and engineering of functionalized materials. We use ab initio calculations based on Density Functional Theory (DFT) to obtain information about the energetics, atomic configuration, and electronic structure of the nanoparticles. Ab initio Molecular Dynamics (MD) is used to study the evolution of the structures of the nanoparticles. To calculate vibrational frequencies, the finite displacement method is employed.
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Date Issued: 2015
Identifier: CFE0006385, ucf:51536
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006385

Title: Model Nanocatalysts with Tunable Reactivity: Tailoring the Structure and Surface Chemistry of Nanomaterials for Energy and Alternative Fuels Catalysis.
Creator: Mistry, Hemma, Roldan Cuenya, Beatriz, Chow, Lee, Stolbov, Sergey, Zhai, Lei, University of Central Florida
Abstract / Description: One of the most pressing challenges of our time is meeting growing global energy demands while limiting human impact on the environment. To meet this challenge, new catalysts are needed to enable carbon neutral energy production processes and low cost synthesis of alternative fuels. In order to design new catalysts for such processes, fundamental understanding is needed on how the structural and chemical properties of nanostructured materials influences their surface chemistry. In this...
Show moreOne of the most pressing challenges of our time is meeting growing global energy demands while limiting human impact on the environment. To meet this challenge, new catalysts are needed to enable carbon neutral energy production processes and low cost synthesis of alternative fuels. In order to design new catalysts for such processes, fundamental understanding is needed on how the structural and chemical properties of nanostructured materials influences their surface chemistry. In this dissertation, I explore how the properties of nanoparticles, such as particle size, shape, composition, and chemical state, can be used to tune their reactivity. For this work, model nanoparticles were synthesized with well-defined structural and chemical properties, and a variety of surface science approaches were used for catalyst characterization. In particular, emphasis was placed on understanding the changes which may occur in the catalyst structure and chemical state during a reaction using advanced in situ techniques and correlating these changes to reactivity. After exploring how nanostructuring the catalyst surface can be used to tune reactivity and how dynamic changes can occur to nanocatalysts in reactive environments, these general principles are applied to a model reaction, the electroreduction of carbon dioxide, which is a promising process for synthesizing valuable products using renewable energy while consuming waste carbon dioxide. I explore the mechanisms behind how catalyst particle size, composition, and oxidation state can be used to improve activity and tune selectivity towards different carbon dioxide reduction products. Such fundamental mechanistic insights are critically needed to design efficient catalysts for this reaction.
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Date Issued: 2016
Identifier: CFE0006482, ucf:51440
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006482

Title: CERIUM OXIDE NANOPARTICLES FOR THE DETECTION OF ANTIMICROBIAL RESISTANCE.
Creator: Noll, Alexander, Perez, J. Manuel, University of Central Florida
Abstract / Description: The rise of antimicrobial resistance demands the development of more rapid screening methods for the detection of antimicrobial resistance in clinical samples to both give the patient the proper treatment and expedite the treatment of patients. Cerium oxide nanoparticles may serve a useful role in diagnostics due to their ability to exist in a mixed valence state and act as either oxidizing agents or reducing agents. Considering that cerium oxide nanoparticles have been shown to shift in...
Show moreThe rise of antimicrobial resistance demands the development of more rapid screening methods for the detection of antimicrobial resistance in clinical samples to both give the patient the proper treatment and expedite the treatment of patients. Cerium oxide nanoparticles may serve a useful role in diagnostics due to their ability to exist in a mixed valence state and act as either oxidizing agents or reducing agents. Considering that cerium oxide nanoparticles have been shown to shift in absorbance upon oxidation, a useful method of antimicrobial resistance detection could be based on the oxidation of cerium oxide nanoparticles. Herein, an assay is described whereby cerium oxide nanoparticle oxidation is a function of glucose metabolism of bacterial samples in the presence of an antimicrobial agent. Cerium oxide nanoparticles were shown to have an absorbance in the range of 395nm upon oxidation by hydrogen peroxide whereas mixed valence cerium oxide nanoparticles lacked an absorbance around 395nm. In the presence the hydrogen peroxide-producing glucose oxidase and either increasing concentrations of glucose or bacterial medium supplemented with increasing concentrations of glucose, cerium oxide nanoparticles were shown to increase in absorbance at 395nm. This oxidation assay was capable of measuring differences in the absorbance of E. coli and S. aureus samples grown in the presence of inhibitory and non-inhibitory concentrations of ampicillin in as little as six hours. Therefore, this cerium oxide nanoparticle oxidation assay may be very useful for use in clinical laboratories for the detection of antimicrobial resistance due to the relatively low cost, no requirement for specialized equipment and, most importantly, the reduced incubation time of the assay to as little as six hours compared to current gold standard antimicrobial resistance detection methods that require 24 hours. This assay may thus also help partially circumvent the issue of knowledge of antimicrobial resistance in infected patients before prescribing improper regimens.
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Date Issued: 2011
Identifier: CFH0003760, ucf:44780
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0003760

Title: Nanoscale Characterization and Mechanism of Electroless Deposition of Silver Metal.
Creator: Grabill, Christopher, Kuebler, Stephen, Beazley, Melanie, Zou, Shengli, Frazer, Andrew, Bhattacharya, Aniket, University of Central Florida
Abstract / Description: This dissertation is an investigation of the nanoscale characteristics and mechanism of electrolessly deposited silver metal seeded by gold nanoparticles. The process of growing seed-nanoparticles on a polymer surface was studied. Several bifunctional amines and organic reducing agents were used to explore how these chemical factors affect the size and distribution of gold nanoparticles formed at the interface. The nanoparticles were characterized by transmission electron microscopy (TEM) and...
Show moreThis dissertation is an investigation of the nanoscale characteristics and mechanism of electrolessly deposited silver metal seeded by gold nanoparticles. The process of growing seed-nanoparticles on a polymer surface was studied. Several bifunctional amines and organic reducing agents were used to explore how these chemical factors affect the size and distribution of gold nanoparticles formed at the interface. The nanoparticles were characterized by transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). An electroless deposition (ED) bath developed by Danscher was selected to study electroless deposition of silver in detail. The chemical species in the bath were varied to determine how concentration, nature of the carboxylate buffering species, and the presence and absence of gum arabic affect the morphology of silver metal formed by ED and the overall rate of deposition at the surface. The kinetics of deposition using the Danscher bath was studied in detail to elucidate the mechanism of ED. Knowledge generated from this investigation can be used to expand applications of silver ED where strict control over the nanoscale morphology of the deposited metal is required to obtain specific chemical and physical properties.
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Date Issued: 2018
Identifier: CFE0007009, ucf:52051
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007009

Title: SCALABLE NANO PARTICLE PRODUCTION OF LOW BIOAVAILABILITY PHARMACEUTICALS FOR AUGMENTED AQUEOUS SOLUBILITY.
Creator: Madden, Aaron, Deng, Wei Wei, University of Central Florida
Abstract / Description: The billion dollar pharmaceutical research and development pipeline suffers greatly from high attrition rates of novel therapeutic compounds within pre-clinical and clinical trials. Poor bioavailability in many new drugs, originating in the various methodologies of high throughput screening, may explain part of these growing failure rates. One interpretation of this phenomenon relies on bioavailability's correlation with aqueous solubility; much modern processing allows chemicals to fully...
Show moreThe billion dollar pharmaceutical research and development pipeline suffers greatly from high attrition rates of novel therapeutic compounds within pre-clinical and clinical trials. Poor bioavailability in many new drugs, originating in the various methodologies of high throughput screening, may explain part of these growing failure rates. One interpretation of this phenomenon relies on bioavailability's correlation with aqueous solubility; much modern processing allows chemicals to fully develop without touching water, yielding upwards of 90% of new chemical entities practically insoluble in aqueous media. Thus, one approach to alleviating bioavailability and potentially clinical attrition rates necessitates augmented aqueous solubility. The amorphous nanoparticle presents the largest boost in aqueous solubility of a chemical through processing alone. In this contribution, we propose electrospray as a novel, competitive candidate to produce pharmaceutical amorphous nanoparticles with the intent of augmenting solubility. Electrospray represents an idyllic nominee for three reasons: repeatability, flexibility, and scalability. Electrospray offers low batch to batch variation with less than 30% relative standard deviation between various droplets. This triumphs over the several orders of magnitude in variation in pneumatic sprays. Electrospray's flexibility draws from its ability to attain diameters over several orders of magnitude, ranging from hundreds of microns to several nanometers; in this contribution droplets are produced between 500 nm and 1 [micro]m. Finally, electrospray displays scalability to any industrial requirement; though a single nozzle operates at mere microliters per hour, a single multiplexed array of emitters may increase this throughput by several orders of magnitude. This exploration, utilizing Indomethacin as a model low solubility chemical, verifies electrospray as a compatible processing tool for the pharmaceutical industry. Scanning electron microscopy coupled with the image analysis software ImageJ gleans the size and shape of emitted (and dried) particles. Amorphicity verification of particles employs grazing angle x-ray diffraction. Finally, ultraviolet and visual spectrum spectroscopy evaluates the solubility advantage of particles.
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Date Issued: 2014
Identifier: CFH0004546, ucf:45179
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004546

Title: SYNTHESIS OF ALKYLTHIOL-CONTAINING FLUORENE DERIVATIVES FOR GOLD NANOPARTICLE FUNCTIONALIZATION.
Creator: Mukundarajan, Sriram, Belfield, Kevin, University of Central Florida
Abstract / Description: A novel synthetic methodology has been developed for attaching fluorene derivatives, containing different types of electron donating and accepting groups at the 2 and 7 positions, to gold nanoparticles of different sizes by exploiting the affinity of the thiol functional group for gold. The distance between the dye and nanoparticles was varied by introducing two alkyl chains containing different number of carbon atoms at the 9 position on the fluorene ring system. The methodology that was...
Show moreA novel synthetic methodology has been developed for attaching fluorene derivatives, containing different types of electron donating and accepting groups at the 2 and 7 positions, to gold nanoparticles of different sizes by exploiting the affinity of the thiol functional group for gold. The distance between the dye and nanoparticles was varied by introducing two alkyl chains containing different number of carbon atoms at the 9 position on the fluorene ring system. The methodology that was developed gave enough scope for performing Radiative Decay Engineering (RDE) studies, in order to investigate the impact of gold nanoparticles on the singlet oxygen quantum yields of fluorene dyes that already exhibit high singlet oxygen quantum yields as well as high two photon absorption (2PA) cross-sections. The dialkylation of the fluorene derivatives was accomplished by reacting the dye with ƒÑ, ƒç-dibromoalkanes containing different number of carbon atoms in a biphasic reaction mixture containing toluene and aqueous sodium hydroxide solution in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The bromine atom on the alkyl chains was converted to thioester by reaction with potassium thioacetate. This was followed by the hydrolysis of the thioester to form the thiol moiety. The compounds synthesized were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Functionalization of gold nanoparticles was attempted by bringing into contact a solution of the thiol compound in toluene and an aqueous gold nanoparticles solution. UV-vis absorbance spectroscopy was used to monitor the progress of the attachment. Surface Enhanced Raman Scattering (SERS) spectroscopy was used to probe the enhancement of Raman signal by the metallic nanoparticles.
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Date Issued: 2005
Identifier: CFE0000769, ucf:46589
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000769

Title: LATTICE VIBRATION STUDY OF SILICA NANOPARTICLE IN SUSPENSION.
Creator: Sachdeva, Parveen, Kumar, Ranganathan, University of Central Florida
Abstract / Description: In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of...
Show moreIn recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded by water molecules has been performed. Periodic boundary condition has been used in all three directions. The effect of nanoparticle size and temperature of system on the thermal conductivity of nanofluids has been studied. It was found that as the size of nanoparticle decreases thermal conductivity of nanofluid increases. This is partially due to the fact that as the diameter of nanoparticle decreases from micrometer to nanometer its surface area to volume ratio increases by a factor of 103. Since heat transfer between the fluid and the nanoparticle takes place at the surface this enhanced surface area gives higher thermal conductivity for smaller particles. Thermal conductivity enhancement is also due to the accumulation of water molecules near the particle surface and the lattice vibration of the nanoparticle. The phonon transfer through the second layer allows the nanofluid thermal conductivity to increase by 23%-27% compared to the base fluid water for 2% concentration of nanosilica.
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Date Issued: 2006
Identifier: CFE0001278, ucf:46897
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001278

Title: GOLD NANOPARTICLE GENERATION USING IN SITU REDUCTION ON A PHOTORESIST POLYMER SUBSTRATE.
Creator: Clukay, Christopher, Kuebler, Stephen, University of Central Florida
Abstract / Description: This report presents evidence that in-situ reduction of metal ions bound to a cross-linked polymer surface does not always result in nanoparticle formation solely at the interface, as is commonly assumed, but also as much as 40 nm deep within the polymer matrix. Tetrachloroaurate ions were bound using a variety of multi-functional amines to cured films of SU-8 -- a cross-linkable epoxide frequently used for micro- and nanofabrication -- and then treated using one of several reducing agents....
Show moreThis report presents evidence that in-situ reduction of metal ions bound to a cross-linked polymer surface does not always result in nanoparticle formation solely at the interface, as is commonly assumed, but also as much as 40 nm deep within the polymer matrix. Tetrachloroaurate ions were bound using a variety of multi-functional amines to cured films of SU-8 -- a cross-linkable epoxide frequently used for micro- and nanofabrication -- and then treated using one of several reducing agents. The resulting gold-nanoparticle decorated films were examined by X-ray photoelectron spectroscopy and by plan-view and cross-sectional transmission electron microscopy. Reduction using sodium borohydride or sodium citrate generates bands of interspersed particles as much as 40 nm deep within the polymer, suggesting both the Au(III) complex and the reducing agent are capable of penetrating the surface and affecting reduction and formation of nanoparticles within the polymer matrix. It is shown that nanoparticle formation can be confined nearer to the polymer interface by using hydroquinone, a sterically bulkier and less flexible reducing agent, or by reacting the surface in aqueous media with high molecular-weight multifunctional amines, that presumably confine Au(III) nearer to the true interface. These finding have important implications for technologies that apply surface bound nanoparticles, including electroless metallization, catalysis, nano-structure synthesis, and surface enhanced spectroscopy.
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Date Issued: 2011
Identifier: CFH0004091, ucf:44794
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004091

Title: ROOM TEMPERATURE SYNTHESIS AND SYSTEMATIC CHARACTERIZATION OF ULTRA-SMALL CERIA NANOPARTICLES.
Creator: Patel, Chetak, Santra, Swadeshmukul, University of Central Florida
Abstract / Description: Cerium oxide (ceria, CeO2) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus...
Show moreCerium oxide (ceria, CeO2) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus acting as an anti-oxidant. This phenomenon has been explained based on the autocatalytic property of ceria NPs. Several methods have been developed for the synthesis of ceria NPs that include flame combustion, hydroxide co-precipitation, hydrothermal/solvothermal, microemulsion, sonochemical and microwave-assisted heating methods and sol-gel method. Ceria NPs synthesized by these methods are often highly aggregated. Furthermore, large scale synthesis of monodispersed CeO2 NPs is quite challenging. Therefore it is desirable to synthesize ceria NPs in bulk quantity keeping its important properties intact, specifically free-radical scavenging property. The main goal of this study is therefore to synthesize ultra-small (< 5.0 nm), high quality monodispersed ceria NPs in large quantities. In this thesis work, I present a couple of room temperature techniques, dilute sodium hydroxide (NaOH) assisted and ethylenediamine (EN) assisted for the synthesis of nearly mono-dispersed, ultra-small (< 5 nm) and water-dispersible ceria NPs. Morphology and particle size of the ceria NPs were investigated through high resolution transmission electron microscopy (HRTEM). The HRTEM analysis confirmed the formation of 3.0 ± 0.5 nm size and 2.5 ± 0.2 nm size highly-crystalline ceria NPs when synthesized using dilute NaOH and EN as solvents, respectively. The nanostructures were characterized by X-ray diffraction (XRD) studies to determine the crystal structure and phase purity of the products. The samples were also thoroughly characterized by X-ray photoelectron spectroscopy (XPS) to determine the oxidation state of cerium ions. The presence of the +3 and +4 oxidation states in the samples was also confirmed from the XPS analysis. The co-existence of these two oxidation states is necessary for their applications as free radical scavenger. The autocatalytic behaviors of the ceria NPs were investigated through a hydrogen peroxide test and monitored by UV-visible transmission spectroscopy.
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Date Issued: 2009
Identifier: CFE0002883, ucf:48043
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002883

Title: Fabrication of Polyelectrolyte Nanoparticles Through Hydrophobic Interaction.
Creator: Catarata, Ruginn Porce, Zhai, Lei, Kang, Ellen, Huo, Qun, University of Central Florida
Abstract / Description: Anticancer drugs like gemcitabine (GEM) are used to treat cancers such as, pancreatic ductal adenocarcinoma (PDAC). However, the use of free gemcitabine yields challenges including cytotoxicity to healthy cells and poor circulation time. By encapsulating GEM in nanoparticles these challenges can be overcome. In this study poly(acrylic acid) (PAA)-GEM nanoparticles are fabricated by coupling GEM onto PAA. The particle formation is driven by the hydrophobic interaction of GEM, which collects in...
Show moreAnticancer drugs like gemcitabine (GEM) are used to treat cancers such as, pancreatic ductal adenocarcinoma (PDAC). However, the use of free gemcitabine yields challenges including cytotoxicity to healthy cells and poor circulation time. By encapsulating GEM in nanoparticles these challenges can be overcome. In this study poly(acrylic acid) (PAA)-GEM nanoparticles are fabricated by coupling GEM onto PAA. The particle formation is driven by the hydrophobic interaction of GEM, which collects in the core of the nanoparticle, forming a PAA shell. The nanoparticles were optimized by studying the PAA/GEM ratio and pH during fabrication. Characteristics of the nanoparticles including size, morphology and surface charge were investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential measurements. Conditions such as ionic stability and pH stability were optimized to achieve high drug loading efficiency. Cell uptake and cytotoxicity studies were used to determine the efficiency of the nanoparticles as drug delivery vehicle.
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Date Issued: 2019
Identifier: CFE0007791, ucf:52364
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007791

Title: THERMAL DETECTION OF BIOMARKERS USING PHASE CHANGE NANOPARTICLES.
Creator: Wang, Chaoming, Su, Ming, University of Central Florida
Abstract / Description: Most of existing techniques cannot be used to detect molecular biomarkers (i.e., protein and DNA) contained in complex body fluids due to issues such as enzyme inhibition or signal interference. This thesis describes a nanoparticle-based thermal detection method for the highly sensitive detections of multiple DNA biomarkers or proteins contained in different type of fluids such as buffer solution, cell lysate and milk by using solid-liquid phase change nanoparticles as thermal barcodes....
Show moreMost of existing techniques cannot be used to detect molecular biomarkers (i.e., protein and DNA) contained in complex body fluids due to issues such as enzyme inhibition or signal interference. This thesis describes a nanoparticle-based thermal detection method for the highly sensitive detections of multiple DNA biomarkers or proteins contained in different type of fluids such as buffer solution, cell lysate and milk by using solid-liquid phase change nanoparticles as thermal barcodes. Besides, this method has also been applied for thrombin detection by using RNA aptamer-functionalized phase change nanoparticles as thermal probes. Furthermore, using nanostructured Si surface that have higher specific area can enhance the detection sensitivity by four times compared to use flat aluminum surfaces. The detection is based on the principle that the temperature of solid will not rise above its melting temperature unless all solid is molten, thus nanoparticles will have sharp melting peak during a linear thermal scan process. A one-to-one correspondence can be created between one type of nanoparticles and one type of biomarker, and multiple biomarkers can be detected simultaneously using different type nanoparticles. The melting temperature and the heat flow reflect the type and the concentration of biomarker, respectively. The melting temperatures of nanoparticles are designed to be over 100Ã‚Â°C to avoid interference from species contained in fluids. The use of thermal nanoparticles allows detection of multiple low concentration DNAs or proteins in a complex fluid such as cell lysate regardless of the color, salt concentration, and conductivity of the sample.
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Date Issued: 2010
Identifier: CFE0003330, ucf:48473
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003330

Title: ENCAPSULATED NANOSTRUCTURED PHASE CHANGE MATERIALS FOR THERMAL MANAGEMENT.
Creator: Hong, Yan, Su, Ming, University of Central Florida
Abstract / Description: A major challenge of developing faster and smaller microelectronic devices is that high flux of heat needs to be removed efficiently to prevent overheating of devices. The conventional way of heat removal using liquid reaches a limit due to low thermal conductivity and limited heat capacity of fluids. Adding solid nanoparticles into fluids has been proposed as a way to enhance thermal conductivity of fluids, but recent results show inconclusive anomalous enhancements in thermal conductivity....
Show moreA major challenge of developing faster and smaller microelectronic devices is that high flux of heat needs to be removed efficiently to prevent overheating of devices. The conventional way of heat removal using liquid reaches a limit due to low thermal conductivity and limited heat capacity of fluids. Adding solid nanoparticles into fluids has been proposed as a way to enhance thermal conductivity of fluids, but recent results show inconclusive anomalous enhancements in thermal conductivity. A possible way to improve heat transfer is to increase the heat capacity of liquid by adding phase change nanoparticles with large latent heat of fusion into the liquid. Such nanoparticles absorb heat during solid to liquid phase change. However, the colloidal suspension of bare phase change nanoparticles has limited use due to aggregation of molten nanoparticles, irreversible sticking on fluid channels, and dielectric property loss. This dissertation describes a new method to enhance the heat transfer property of a liquid by adding encapsulated phase change nanoparticles (nano-PCMs), which will absorb thermal energy during solid-liquid phase change and release heat during freeze. Specifically, silica encapsulated indium nanoparticles, and polymer encapsulated paraffin (wax) nanoparticles have been prepared using colloidal method, and dispersed into poly-±-olefin (PAO) and water for high temperature and low temperature applications, respectively. The shell, with a higher melting point than the core, can prevent leakage or agglomeration of molten cores, and preserve the dielectric properties of the base fluids. Compared to single phase fluids, heat transfer of nanoparticle-containing fluids have been significantly enhanced due to enhanced heat capacities. The structural integrity of encapsulation allows repeated uses of nanoparticles for many cycles. By forming porous semi crystalline silica shells obtained from water glass, supercooling has been greatly reduced due to low energy barrier of heterogeneous nucleation. Encapsulated phase change nanoparticles have also been added into exothermic reaction systems such as catalytic and polymerization reactions to effectively quench local hot spots, prevent thermal runaway, and change product distribution. Specifically, silica-encapsulated indium nanoparticles, and silica encapsulated paraffin (wax) nanoparticles have been used to absorb heat released in catalytic reaction, and to mitigate the gel effect during polymerization, respectively. The reaction rates do not raise significantly owing to thermal buffering using phase change nanoparticles at initial stage of thermal runaway. The effect of thermal buffering depends on latent heats of fusion of nanoparticles, and heat releasing kinetics of catalytic reactions and polymerizations. Micro/nanoparticles of phase change materials will open a new dimension for thermal management of exothermic reactions.
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Date Issued: 2011
Identifier: CFE0003698, ucf:48816
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003698

Title: Fate of Coated Zinc Oxide in Municipal Solid Waste Landfills.
Creator: Bolyard, Stephanie, Reinhart, Debra, Santra, Swadeshmukul, Randall, Andrew, University of Central Florida
Abstract / Description: Given the increase in nanomaterial (NM) use in consumer products and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology use is still in its early stages, there are currently no regulations pertaining to the disposal of NMs and their fate in MSW landfills is still unknown. Understanding the fate of NMs in MSW landfills is vital to ensure the...
Show moreGiven the increase in nanomaterial (NM) use in consumer products and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology use is still in its early stages, there are currently no regulations pertaining to the disposal of NMs and their fate in MSW landfills is still unknown. Understanding the fate of NMs in MSW landfills is vital to ensure the proper handling of these novel materials from cradle to grave; such research will provide information on how these NMs can be safely introduced into the environment. This research seeks to understand the fate of NMs within waste environments by examining the interactions between NMs and landfill leachate components. The primary focus of this thesis is the effect of Zinc Oxide (ZnO) on biological landfill processes, solids aggregation, and chemical speciation of Zn in landfill leachate following the addition of crystalline, nano-sized ZnO coated with triethoxycaprylylsilane. This research (1) observed the effects of coated ZnO on five-day biochemical oxygen demand (BOD5) and biochemical methane potential (BMP), (2) examined effects of solids aggregation on the fate of ZnO, (3) quantified the concentration of Zinc (Zn) by size fractions, and (4) modeled the chemical speciation of Zn in landfill leachate using Visual MINTEQ.No change in dissolved Zn was observed after coated ZnO was exposed to (")middle-aged(") leachate. Upon exposure to (")mature(") leachate there was an increase in dissolved Zn assumed to be a result of the dissociation of ZnO. Solids data supported the aggregation of particles in both middle aged and mature leachate. There was an increase in the Zn concentration in leachate fractions greater than 1500 nm presumably due to the dispersion of normally insoluble ZnO nanoparticles (NPs) following the interaction with humic acids (HA). ZnO did not inhibit anaerobic or aerobic processes in either middle aged or mature leachate, presumably due to the relatively low concentration of dissolved ionic Zn. Despite the observation of increased dissociation upon exposure to mature leachate, the presence of dissolved organic matter (DOM) may have hindered the ability for dissolved ionic Zn to become bioavailable. Fractionation, BOD5 and BMP tests, and chemical speciation modeling provided insight on the mobility of ZnO in landfills and the absence of inhibitory effects on landfill processes. Aggregation of ZnO NPs may prevent movement through traditional containment systems (i.e. geomembrane liners) due to the increased particle size. However, the increased dispersion suggests that ZnO NPs will be transported out of the landfill in the leachate, however biological treatment of leachate should be unaffected by the presence of ZnO. The bioavailability of Zn was not substantially affected by the presence of ZnO due to affinity of dissolved Zn for DOM. However, due to the heterogeneity of landfill leachate and the utilization of different NM coatings, it is challenging to predict the overall mobility of other NMs in a landfill.
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Date Issued: 2012
Identifier: CFE0004264, ucf:49509
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004264

Title: Novel Nanostructures and Processes for Enhanced Catalysis of Composite Solid Propellants.
Creator: Draper, Robert, Seal, Sudipta, Heinrich, Helge, Zhai, Lei, University of Central Florida
Abstract / Description: The purpose of this study is to examine the burning behaviour of composite solid propellants (CSP)in the presence of nanoscale, heterogenous catalysts. The study targets the decomposition of am-monium perchlorate (AP) as a key component in the burning profile of these propellants, and seeksto identify parameters of AP decomposition reaction that can be affected by catalytic additives.The decomposition behavior of AP was studied in the presence of titanium dioxide nanoparticlesin varying...
Show moreThe purpose of this study is to examine the burning behaviour of composite solid propellants (CSP)in the presence of nanoscale, heterogenous catalysts. The study targets the decomposition of am-monium perchlorate (AP) as a key component in the burning profile of these propellants, and seeksto identify parameters of AP decomposition reaction that can be affected by catalytic additives.The decomposition behavior of AP was studied in the presence of titanium dioxide nanoparticlesin varying configurations, surface conditions, dopants, morphology, and synthesis parameters withthe AP crystals. The catalytic nanoparticles were found to enhance the decomposition rate of theammonium perchlorate, and promote an accelerated burning rate of CSP propellants containingthe additives. Furthermore, different configurations were shown to have varying degrees of effec-tiveness in promoting the decomposition behaviour.To study the effect of the catalyst's configuration in the bulk propellant, controlled dispersion con-ditions of the nanoparticle catalysts were created and studied using differential scanning calorime-try, as well as model propellant strand burning. The catalysts were shown to promote the greatestenthalpy of reaction, as well as the highest burn rate, when the AP crystals were recrystalizedaround the nanoparticle additives. This is in contrast to the lowest enthalpy condition, which cor-responded to catalysts being dispersed upon the AP crystal surface using bio-molecule templates.Additionally, a method of facile, visible light nanoparticle tracking was developed to study theeffect of mixing and settling parameters on the nano-catalysts. To accomplish this, the titaniananoparticles were doped with fluorescent europium molecules to track the dispersion of the cat-alysts in the propellant binder. This method was shown to succesfully allow for dispersion andagglomeration monitoring without affecting the catalytic effect of the TiO2 nanoparticles.
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Date Issued: 2013
Identifier: CFE0004991, ucf:49559
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004991

Title: PLASMON ENHANCED NEAR-FIELD INTERACTIONS IN SURFACE COUPLED NANOPARTICLE ARRAYS FOR INTEGRATED NANOPHOTONIC DEVICES.
Creator: Ghoshal, Amitabh, Kik, Pieter, University of Central Florida
Abstract / Description: The current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at...
Show moreThe current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at optical and infrared frequencies. Numerous plasmon based integrated optical devices such as waveguides, splitters, resonators and multimode interference devices have been developed, however no standard integrated device for coupling light into nanoscale optical circuits exists. In this thesis we experimentally and theoretically investigate the excitation of propagating surface plasmons via resonant metal nanoparticle arrays placed in close proximity to a metal surface. It is shown that this approach can lead to compact plasmon excitation devices. Full-field electromagnetic simulations of the optical illumination of metal nanoparticle arrays near a metal film reveal the presence of individual nanoparticle resonances and collective grating-like resonances related to propagating surface plasmons within the periodic array structure. Strong near-field coupling between the nanoparticle and grating resonances is observed, and is successfully described by a coupled oscillator model. Numerical simulations of the effect of nanoparticle size and shape on the excitation and dissipation of surface plasmons reveal that the optimum particle volume for efficient surface plasmon excitation depends sensitively on the particle shape. This observation is quantitatively explained in terms of the shape-dependent optical cross-section of the nanoparticles. Reflection measurements on nanoparticle arrays fabricated using electron-beam lithography confirm the predicted particle-grating interaction. An unexpected polarization-dependent splitting of the film-mediated collective resonance is successfully attributed to the existence of out-of plane polarization modes of the metal nanoparticles. In order to distinguish between the excitation of propagating surface plasmons and localized nanoparticle plasmons, spectrally resolved leakage radiation measurements are presented. Based on these measurements, a universally applicable method for measuring the wavelength dependent efficiency of coupling free-space radiation into guided surface plasmon modes on thin films is developed. Finally, it is shown that the resonantly enhanced near-field coupling the nanoparticles and the propagating surface plasmons can lead to optimized coupler device dimensions well below 10 microns.
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Date Issued: 2010
Identifier: CFE0003091, ucf:48322
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003091

Title: Electrospray and Superlens Effect of Microdroplets for Laser-Assisted Nanomanufacturing.
Creator: Castillo Orozco, Eduardo, Kumar, Ranganathan, Mansy, Hansen, Peles, Yoav, University of Central Florida
Abstract / Description: Nanoparticles of various materials are known to exhibit excellent mechanical, chemical, electrical, and optical properties. However, it is difficult to deposit and transform nanoparticles into large two-dimensional and three-dimensional structures, such as thin films and discrete arrays. Electrospray technology and laser heating enable the deposition of these nanoparticles through the dual role of microdroplets as nanoparticle carriers and superlenses. The main goals of this dissertation are...
Show moreNanoparticles of various materials are known to exhibit excellent mechanical, chemical, electrical, and optical properties. However, it is difficult to deposit and transform nanoparticles into large two-dimensional and three-dimensional structures, such as thin films and discrete arrays. Electrospray technology and laser heating enable the deposition of these nanoparticles through the dual role of microdroplets as nanoparticle carriers and superlenses. The main goals of this dissertation are to delineate the electrospray modes, to achieve subwavelength focusing, and to enable a process for the deposition of nanoparticles into microlayers and discrete nanodots (a nanodot is a cluster of nanoparticles) on rigid and flexible substrates. This additive manufacturing process is based on the electrospray generation of water microdroplets that carry nanoparticles onto a substrate and the laser sintering of these nanoparticles. The process involves injecting nanoparticles (contained inside electric field-driven water microdroplets) into a hollow laser beam. The laser beam heats the droplets, causing the water to evaporate and the nanoparticles to sinter and form deposit of material on the substrate.The electrohydrodynamic inkjet printing of nanoparticle suspensions has been accomplished by the operation of an electrospray in microdripping mode and it allows the deposition of monodisperse microdroplets containing nanoparticles into discrete nanodot arrays, narrow lines, and thin films. For flow rates with low Reynolds number, the mode changes from dripping to microdripping mode, and then to a planar oscillating microdripping mode as the electric capillary number, Cae increases. The microdripping mode which is important for depositing discrete array of nanodots is found to occur in a narrow range, 2 ? Cae ? 2.5. The effect of the physical properties on the droplet size and frequency of droplet formation is more precisely described by the relative influence of the electric, gravity, viscous, and capillary forces. A scaling analysis is derived from a fundamental force balance and has yielded a parameter based on the electric capillary number, capillary number, and Bond number. Results for different nanoparticle suspensions with a wide range of physical properties show that the normalized radius of droplet, can be correlated using this parameter in both dripping and microdripping modes. The same parameter also correlates the normalized frequency of droplet formation, Nd* as an increasing function in the microdripping mode. Viscosity affects the shape of the cone by resisting its deformation and thus promoting a stable microdripping mode. Reduction in surface tension decreases the droplet size in the electrospray modes. However, the capillary size and electrical conductivity have minimal effect on the size of the ejected droplets. Electrical conductivity affects the transition between microdripping and oscillating microdripping modes. Based on this analysis, it is possible to design the electrospray to produce uniform monodisperse droplets by manipulating the voltage at the electrode, for any desired nanoparticle concentration of a suspension to be sintered on a substrate. For the fabrication of nanodots, a laser beam of wavelength ? = 1064 nm was focused to a diameter smaller than its wavelength. When the microdroplets did not carry nanoparticles, the subwavelength focusing of the laser yielded nanoholes smaller than its wavelength. Results show that tiny features with high resolution can be created by loading microdroplets with nanoparticles and squeezing the laser beam to subwavelength regions. Nanodots of silicon and germanium with diameters between 100 - 500 nm have been deposited on a silicon substrate. This study demonstrates an interdisciplinary mechanism to achieve subwavelength focusing in a laser process. In this process, the microdroplets serve as both a nanoparticle carrier and a superlens that focuses a laser beam to subwavelength diameters up to ? /10, thus overcoming the diffraction limit. The microdroplets are generated from a suspension of nanoparticles using an electrospray technique and the superlens characteristic of these microdroplets is attributed to three optical phenomena such as Maxwell's fish eye lens or L(&)#252;neberg lens, evanescent waves by laser scattering, and evanescent waves by the total internal reflection principle. A microfluidic cooling effect can also contribute to creating subwavelength features. In summary, this work describes a new laser-assisted additive manufacturing process for the fabrication of nanodots and microlayers using nanoparticles of different materials. In this process, microdroplets from an electrospray are used as nanoparticle carriers and superlenses to focus the laser to a diameter smaller than its wavelength. While this process is demonstrated to produce subwavelength holes and nanodots, the process is scalable to produce narrow lines and thin films of semiconductor materials by an additive manufacturing technique. This process extends the application of infrared lasers to the production of nanostructures and nanofeatures, and, therefore, provides a novel technology for nanomanufacturing.
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Date Issued: 2018
Identifier: CFE0007563, ucf:52579
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007563

Title: Size, Shape, Composition and Chemical state effects in nanocatalysis.
Creator: Ahmadi, Mahdi, Roldan Cuenya, Beatriz, Rahman, Talat, Kara, Abdelkader, Coffey, Kevin, University of Central Florida
Abstract / Description: The field of nanocatalysis has gained significant attention in the last decades due to the numerous industrial applications of nanosized catalysts. Size, shape, structure, and composition of the nanoparticles (NPs) are the parameters that can affect the reactivity, selectivity and stability of nanocatalysts. Therefore, understanding how these parameters affect the catalytic properties of these systems is required in order to engineer them with a given desired performance. It is also important...
Show moreThe field of nanocatalysis has gained significant attention in the last decades due to the numerous industrial applications of nanosized catalysts. Size, shape, structure, and composition of the nanoparticles (NPs) are the parameters that can affect the reactivity, selectivity and stability of nanocatalysts. Therefore, understanding how these parameters affect the catalytic properties of these systems is required in order to engineer them with a given desired performance. It is also important to gain insight into the structural evolution of the NP catalysts under different reaction conditions to design catalysts with long durability under reaction condition. In this dissertation a synergistic combination of in situ, ex situ and operando state-of-the art techniques have allowed me to explore a variety of parameters and phenomena relevant to nanocatalysts by systematically tuning the NP size, chemical state, composition and chemical environment.
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Date Issued: 2016
Identifier: CFE0006243, ucf:51084
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006243

Title: Folate conjugated hyperbranched polyester nanoparticles for prostate tumor-targeted delivery of a cytotoxic peptide via prostate specific membrane antigen.
Creator: Flores-Fernandez, Orielyz, Perez Figueroa, J. Manuel, Campiglia, Andres, Yestrebsky, Cherie, Harper, James, Khaled, Annette, University of Central Florida
Abstract / Description: Prostate Cancer is the second most deadly cancer in men, after lung cancer. The need for new and effective therapeutics that can constrain prostate cancer progression are challenged by the lack of suitable delivery strategies that target prostate cancer tissue. To study CT20p as potential chemotherapeutic agent in the treatment of prostate cancer we proposed the use of targetable hyperbranched polyester (HBPE) based nanoparticles as delivery system. Folic acid was conjugated to the...
Show moreProstate Cancer is the second most deadly cancer in men, after lung cancer. The need for new and effective therapeutics that can constrain prostate cancer progression are challenged by the lack of suitable delivery strategies that target prostate cancer tissue. To study CT20p as potential chemotherapeutic agent in the treatment of prostate cancer we proposed the use of targetable hyperbranched polyester (HBPE) based nanoparticles as delivery system. Folic acid was conjugated to the nanocarrier to improve the selectivity of the nanoparticle towards specific cell surface targets in prostate cancer cell lines. Specifically we evaluated LNCaP that up-regulated the PSMA receptor. The synthesis of folate conjugated hyperbranched polyester nanoparticles was accomplished using an aliphatic and biodegradable hyperbranched polyester (HBPE). HBPE was prepared from commercially available diethyl malonate and 4-bromobutyl acetate. Our AB2 type monomer displays a three-bond connectivity that grows three-dimensionally under specific polymerization conditions. The product, HBPE, is a polymer with globular configuration that contains surface carboxylic acid groups and holds hydrophobic cavities. Carboxylated HBPE nanoparticles were synthesized via solvent diffusion method. A variety of hydrophobic cargos including: dyes (DiR and DiI) and the cytotoxic peptide CT20p were successfully encapsulated. DLS along with STEM imaging reveal nanoparticle preparations with ~100 nm size. Using water-soluble carbodiimide chemistry, surface modifications were accomplished. Available carboxylic acid groups were conjugated to aminated folic acid to yield folate functionalized nanoparticles.We explore the targeting capability of the Folate-HBPE nanoparticles and demonstrated that the cell internalization of Folate-HBPE into prostate cancer cell lines (LNCaP and PSMA (+) PC-3) was attained via a PSMA-mediated targeting mechanism. Furthermore, when CT20p was delivered to PSMA expressing PCa cells, detachment and death was observed; together with a reduction in the levels of ?1 integrin (CD29) expression, an integrin implicate in cell communication and cell adhesion. CT20p inhibits cell proliferation within 24 h and produce significant cell death after 48 h post treatment. The IC50 of CT20p was calculated at ~7 nM. Additionally, we investigated the capability of Folate-HBPE(CT20p) to perform as a therapeutic agent, in an in vivo setup, using a murine prostate tumor model. The Folate-PEG-HBPE NPs protected CT20p while in circulation and allowed effective uptake by PSMA-mediated targeting. Treatment with Folate-HBPE(CT20p) display localize tumor targeting and significant tumor growth inhibition in PSMA(+) PCa cell lines within days. Together these results suggest the potential of Folate-HBPE(CT20p) nanoparticles in the treatment of prostate cancer.
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Date Issued: 2015
Identifier: CFE0006216, ucf:51112
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006216

Title: Development of enzyme-free hydrogen peroxide biosensor using cerium oxide and mechanistic study using in-situ spectro-electrochemistry.
Creator: Saraf, Shashank, Seal, Sudipta, Cho, Hyoung Jin, Zhai, Lei, Heinrich, Helge, Harper, James, University of Central Florida
Abstract / Description: During recent development, it has been demonstrated that cerium oxide nanoparticles (CNPs) have exhibited catalytic activity which mimics naturally existing enzymes such as superoxide dismutase (SOD) and catalase. The underlying mechanism is attributed to the modulation of oxygen vacancies on CNPs lattice by dynamic switching of the oxidation states between Ce3+ and Ce4+ due to the electron transfer resulting from the redox reaction between CNPs and reactive oxygen species such as hydrogen...
Show moreDuring recent development, it has been demonstrated that cerium oxide nanoparticles (CNPs) have exhibited catalytic activity which mimics naturally existing enzymes such as superoxide dismutase (SOD) and catalase. The underlying mechanism is attributed to the modulation of oxygen vacancies on CNPs lattice by dynamic switching of the oxidation states between Ce3+ and Ce4+ due to the electron transfer resulting from the redox reaction between CNPs and reactive oxygen species such as hydrogen peroxide (H2O2). Thereby the redox potential of CNPs is dependent on the surface chemistry i.e. the surface concentration of Ce3+ and Ce4+ Currently, the ratio of Ce3+/ Ce4+ in CNPs is characterized ex-situ using XPS or TEM which involves sample drying and exposure to high energy X-rays and electron beam, respectively. Sample drying and high energy beam exposure could lead to sample deterioration. The goal of the study is to explore a technique to characterize CNPs in-situ and identify the surface chemistry of CNPs. The in-situ investigation of CNPs was carried using spectroelectrochemistry wherein the electrochemical and optical measurements are carried out simultaneously. Detailed optical characterization of two different CNPs having different catalytic activity were carried under oxidation and reduction environments. Analysis of spectra revealed widely different redox potential for CNPs which was a function of pH and composition of buffer solution. In second part of dissertation a suitable surface chemistry of CNPs is investigated to replace the enzyme in biosensor assembly to allow amperometric detection of H2O2 in physiological conditions. Upon electrochemical investigation of the physio-chemical properties of CNPs, it was found that CNPs having higher surface concentration of Ce4+ as compared to Ce3+ oxidation states, demonstrated increased catalytic activity towards H2O2. The addition of CNPs resulted in 5 orders of increment in amperometric current with a response time of 400 msec towards detection of H2O2 and exhibited excellent selectivity in presence of interfering species. Additionally, cerium oxide was successfully integrated into the biosensor assembly through the anodic electrodeposition, which allowed the transfer of electron generated from the CNPs in the redox reaction to the electrode and demonstrated successful sensing of H2O2. Furthermore, to achieve detection of H2O2 in physiological conditions, CNPs were integrated with nanoporous gold (NPG) which exhibited anti-biofouling properties. The anti-biofouling property of NPG was investigated using electrochemical techniques and showed excellent signal retention in physiological concentration of albumin proteins. The novel study targets at developing robust enzyme free biosensor by integrating the detection ability of CNPs with the anti-biofouling activity of NPG based electrode.
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Date Issued: 2016
Identifier: CFE0006498, ucf:51404
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006498

Title: The CT20 peptide as an agent for cancer treatment.
Creator: Bassiouni, Rania, Khaled, Annette, Altomare, Deborah, Zhao, Jihe, Estevez, Alvaro, University of Central Florida
Abstract / Description: Due to cancer recurrence and the development of drug resistance, metastatic breast cancer is a leading cause of death in women. In the search for a new therapeutic to treat metastatic disease, we discovered CT20p, an amphipathic peptide based on the C-terminus of Bax. Due to inherent properties of its sequence and similarity to antimicrobial peptides, CT20p is a promising cytotoxic agent whose activity is distinct from the parent protein (e.g. does not cause apoptosis). CT20p is not membrane...
Show moreDue to cancer recurrence and the development of drug resistance, metastatic breast cancer is a leading cause of death in women. In the search for a new therapeutic to treat metastatic disease, we discovered CT20p, an amphipathic peptide based on the C-terminus of Bax. Due to inherent properties of its sequence and similarity to antimicrobial peptides, CT20p is a promising cytotoxic agent whose activity is distinct from the parent protein (e.g. does not cause apoptosis). CT20p is not membrane permeable but can be introduced to cells using polymeric nanoparticles, a method that promotes efficient delivery of the peptide into the intracellular environment.We demonstrated that CT20p was cytotoxic using triple negative breast cancer (TNBC) cell lines, primary breast tumor tissue, and breast tumor murine xenografts. Importantly, normal breast epithelial cells and normal primary breast cells were resistant to the lethal effects of the peptide. Examination of multiple cellular processes showed that CT20p causes cell death by promoting cytoskeletal disruption, cell detachment, and loss of substrate-mediated survival signals.In order to identify the intracellular target of CT20p, we performed pull-down experiments using a biotinylated peptide and found that CT20p binds directly to a type II chaperonin called chaperonin containing T-complex (CCT), which is essential for the folding of actin and tubulin into their native forms. The resulting effect of CT20p upon the cytoskeleton of cancer cells is disruption of vital cellular processes such as migration and adhesion. CCT gene expression and protein levels were examined across several breast cancer cell lines, and we found that susceptibility to CT20p correlated with higher CCT levels. Using human cancer tissue microarrays, we determined that CCT was present in significantly higher amounts in tumor tissues compared to normal tissues and that expression often increased with advanced cancer stage. These results indicate that CCT is a promising therapeutic target for the treatment of metastatic breast cancer and suggest that the use of cancer-targeted nanoparticles loaded with CT20p is a novel and effective therapeutic strategy for cancers, such as TNBC, that recur and are refractory to current treatments.
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Date Issued: 2015
Identifier: CFE0006207, ucf:51095
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006207

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