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Title: THEORETICAL TAILORING OF PERFORATED THIN SILVER FILMS FOR AFFINITY SURFACE PLASMON RESONANCE BIOSENSOR APPLICATIONS.
Creator: Gongora Jr., Renan, Zou, Shengli, University of Central Florida
Abstract / Description: Metallic films, in conjunction with biochemical-targeted probes, are expected to provide early diagnosis, targeted therapy and non-invasive monitoring for epidemiology applications. The resonance wavelength peaks, both plasmonic and Wood-Rayleigh Anomalies (WRAs), in the scattering spectra are affected by the metallic architecture. As of today, much research has been devoted to extinction efficiency in the plasmonic region. However, Wood Rayleigh Anomalies (WRAs) typically occur at...
Show moreMetallic films, in conjunction with biochemical-targeted probes, are expected to provide early diagnosis, targeted therapy and non-invasive monitoring for epidemiology applications. The resonance wavelength peaks, both plasmonic and Wood-Rayleigh Anomalies (WRAs), in the scattering spectra are affected by the metallic architecture. As of today, much research has been devoted to extinction efficiency in the plasmonic region. However, Wood Rayleigh Anomalies (WRAs) typically occur at wavelengths associated with the periodic distance of the structures. A significant number of papers have already focused on the plasmonic region of the visible spectrum, but a less explored area of research was presented here; the desired resonance wavelength region was 400-500nm, corresponding to the WRA for the silver film with perforated hole with a periodic distance of 400nm. Simulations obtained from the discrete dipole approximation (DDA) method, show sharp spectral bands (either high or low scattering efficiencies) in both wavelength regions of the visible spectrum simulated from Ag film with cylindrical hole arrays In addition, surprising results were obtained in the parallel scattering spectra,where the electric field is contained in the XY plane, when the angle between the metallic surface and the incident light was adjusted to 14 degrees; a bathochromic shift was observed for the WRA peak suggesting a hybrid resonance mode. Metallic films have the potential to be used in instrumental techniques for use as sensors, i.e. surface plasmon resonance affinity biosensors, but are not limited to such instrumental techniques. Although the research here was aimed towards affinity biosensors, other sensory designs can benefit from the optimized Ag film motifs. The intent of the study was to elucidate metal film motifs, when incorporated into instrumental analysis, allowing the quantification of genetic material in the visible region. Any research group that routinely benefits from quantification of various analytes in solution matrices will also benefit from this study, as there are a bewildering number of instrumental sensory methods and setups available.
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Date Issued: 2014
Identifier: CFH0004538, ucf:45155
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004538

Title: Predictive Modeling of Functional Materials for Catalytic and Sensor Applications.
Creator: Rawal, Takat, Rahman, Talat, Chang, Zenghu, Leuenberger, Michael, Zou, Shengli, University of Central Florida
Abstract / Description: The research conducted in my dissertation focuses on theoretical and computational studies of the electronic and geometrical structures, and the catalytic and optical properties of functional materials in the form of nano-structures, extended surfaces, two-dimensional systems and hybrid structures. The fundamental aspect of my research is to predict nanomaterial properties through ab-initio calculations using methods such as quantum mechanical density functional theory (DFT) and kinetic Monte...
Show moreThe research conducted in my dissertation focuses on theoretical and computational studies of the electronic and geometrical structures, and the catalytic and optical properties of functional materials in the form of nano-structures, extended surfaces, two-dimensional systems and hybrid structures. The fundamental aspect of my research is to predict nanomaterial properties through ab-initio calculations using methods such as quantum mechanical density functional theory (DFT) and kinetic Monte Carlo simulation, which help rationalize experimental observations, and ultimately lead to the rational design of materials for the electronic and energy-related applications. Focusing on the popular single-layer MoS2, I first show how its hybrid structure with 29-atom transition metal nanoparticles (M29 where M=Cu, Ag, and Au) can lead to composite catalysts suitable for oxidation reactions. Interestingly, the effect is found to be most pronounced for Au29 when MoS2 is defect-laden (S vacancy row). Second, I show that defect-laden MoS2 can be functionalized either by deposited Au nanoparticles or when supported on Cu(111) to serve as a cost-effective catalyst for methanol synthesis via CO hydrogenation reactions. The charge transfer and electronic structural changes in these sub systems lead to the presence of 'frontier' states near the Fermi level, making the systems catalytically active. Next, in the emerging area of single metal atom catalysis, I provide rationale for the viability of single Pd sites stabilized on ZnO(101 ?0) as the active sites for methanol partial oxidation, an important reaction for the production of H2. We trace its excellent activity to the modified electronic structure of the single Pd site as well as neighboring Zn cationic sites. With the DFT-calculated activation energy barriers for a large set of reactions, we perform ab-initio kMC simulations to determine the selectivity of the products (CO2 and H2). These findings offer an opportunity for maximizing the efficiency of precious metal atoms, and optimizing their activity and selectivity (for desired products). In related work on extended surfaces while trying to explain the Scanning Tunneling Microscopy images observed by our experimental collaborators, I discovered a new mechanism involved in the process of Ag vacancy formation on Ag(110), in the presence of O atoms which leads to the reconstruction and eventually oxidation of the Ag surface. In a similar vein, I was able to propose a mechanism for the orange photoluminescence (PL), observed by our experimental collaborators, of a coupled system of benzylpiperazine (BZP) molecule and iodine on a copper surface. Our results show that the adsorbed BZP and iodine play complimentary roles in producing the PL in the visible range. Upon photo-excitation of the BZP-I/CuI(111) system, excited electrons are transferred into the conduction band (CB) of CuI, and holes are trapped by the adatoms. The relaxation of holes into BZP HOMO is facilitated by its realignment. Relaxed holes subsequently recombine with excited electrons in the CB of the CuI film, thus producing a luminescence peak at ~2.1 eV. These results can be useful for forensic applications in detecting illicit substances.
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Date Issued: 2017
Identifier: CFE0006783, ucf:51813
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006783

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: Light Scattering Property of Gold Nanoparticles with Applications to Biomolecule Detection and Analysis.
Creator: Zheng, Tianyu, Huo, Qun, Zou, Shengli, Gesquiere, Andre, Kang, Hyeran, Zhai, Lei, University of Central Florida
Abstract / Description: Gold nanoparticles (AuNPs) have unique optical and chemical properties. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement. The combined use of AuNPs and DLS has led to a novel analytical assay technology called D2Dx (from diameter to diagnostics). Herein, my dissertation highlights the extended use of D2Dx for biomolecule detection and analysis. Under this general theme, Chapter 1 provides some background information of AuNPs, DLS, the...
Show moreGold nanoparticles (AuNPs) have unique optical and chemical properties. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement. The combined use of AuNPs and DLS has led to a novel analytical assay technology called D2Dx (from diameter to diagnostics). Herein, my dissertation highlights the extended use of D2Dx for biomolecule detection and analysis. Under this general theme, Chapter 1 provides some background information of AuNPs, DLS, the principle of D2Dx technique and its potential applications. Chapter 2 summarizes a study on the effect of AuNP concentrations and laser power on the hydrodynamic size measurement of AuNPs by DLS. This study demonstrated the multiple scattering effect on DLS analysis, and how to use the exceptionally high sensitivity of DLS in AuNP aggregate detection for bioassay design and development. Chapter 3 explores a cooperative interaction between AuNP and certain proteins in blood serum that are key to the immune system, leading to a novel diagnostic tool that can conveniently monitor the humoral immunity development from neonates to adults and detect active infections in animals. Chapter 4 reports an application of D2Dx technique for acute viral infection detection based on the active immune responses elicited from mouse models infected with influenza virus. Chapter 5 describes another application of D2Dx for prostate cancer detection. The D2Dx assay identifies prostate cancer patients from non-cancer controls with improved specificity and sensitivity than PSA test. Chapter 6 demonstrates the use of AuNPs and DLS for hydrodynamic size measurement of protein disulfide isomerase with two different conformations. Chapter 7 investigates the concentration-dependent self-assembling behavior of ribostamycin through its interaction with AuNPs in aqueous solution. Overall, this dissertation established several lines of applications of using AuNPs and DLS for biomolecular research and in vitro diagnostics.
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Date Issued: 2018
Identifier: CFE0007385, ucf:52056
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007385

Title: Polyelectrolyte complexes based on poly(acrylic acid): mechanics and applications.
Creator: Lu, Xiaoyan, Zhai, Lei, Zou, Shengli, Chumbimuni Torres, Karin, Kolpashchikov, Dmitry, Dong, Yajie, University of Central Florida
Abstract / Description: Poly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic conditionwhen the carboxylic group loses a proton. These carboxylate group can interact with polycationsand metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable propertiesand multifunctional nanoscale structures through chemical reactions. This research focuses onnanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferricion concentration on the...
Show morePoly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic conditionwhen the carboxylic group loses a proton. These carboxylate group can interact with polycationsand metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable propertiesand multifunctional nanoscale structures through chemical reactions. This research focuses onnanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferricion concentration on the mechanical properties of PAA-based single naonofiber by using dark fieldmicroscopy imaging and persistence length analysis. The application of PAA-based nanofibermats loaded with MnO2 for supercapacitors was also explored. As a free-standing and flexiblesupercapacitor electrode, the nanofiber mat exhibited outstanding properties including high specificcapacitance, excellent reversible redox reactions, and fast charge/discharge ability. Since PAA is abiocompatible polymer, PAA-based PEC was applied as a drug-carrier in a drug delivery system.In this project, core-shell nanoparticles were fabricated with chitosan as the core and PAA as theshell to incorporate with the drug gemcitabine. Several parameters were investigated to obtainthe optimal nanoparticle size. The as-prepared drug delivery system shows prolonged releasingprofile.
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Date Issued: 2018
Identifier: CFE0007045, ucf:52004
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007045

Title: Optical Properties of Single Nanoparticles and Two-dimensional Arrays of Plasmonic Nanostructures.
Creator: Zhou, Yadong, Zou, Shengli, Harper, James, Zhai, Lei, Chen, Gang, Zheng, Qipeng, University of Central Florida
Abstract / Description: The tunability of plasmonic properties of nanomaterials makes them promising in many applications such as molecular detection, spectroscopy techniques, solar energy materials, etc. In the thesis, we mainly focus on the interaction between light with single nanoparticles and two-dimensional plasmonic nanostructures using electrodynamic methods. The fundamental equations of electromagnetic theory: Maxwell's equations are revisited to solve the problems of light-matter interaction, particularly...
Show moreThe tunability of plasmonic properties of nanomaterials makes them promising in many applications such as molecular detection, spectroscopy techniques, solar energy materials, etc. In the thesis, we mainly focus on the interaction between light with single nanoparticles and two-dimensional plasmonic nanostructures using electrodynamic methods. The fundamental equations of electromagnetic theory: Maxwell's equations are revisited to solve the problems of light-matter interaction, particularly the interaction of light and noble nanomaterials, such as gold and silver. In Chapter 1, Stokes parameters that describe the polarization states of electromagnetic wave are presented. The scattering and absorption of a particle with an arbitrary shape are discussed. In Chapter 2, several computational methods for solving the optical response of nanomaterials when they are illuminated by incident light are studied, which include the Discrete Dipole Approximation (DDA) method, the coupled dipole (CD) method, etc. In Chapter 3, the failure and reexamination of the relation between the Raman enhancement factor and local enhanced electric field intensity is investigated by placing a molecular dipole in the vicinity of a silver rod. Using a silver rod and a molecular dipole, we demonstrate that the relation generated using a spherical nanoparticle cannot simply be applied to systems with particles of different shapes. In Chapter 4, a silver film with switchable total transmission/reflection is discussed. The film is composed of two-dimensional rectangular prisms. The factors affecting the transmission (reflection) as well as the mechanisms leading to the phenomena are studied. Later, in Chapter 5 and 6, the sandwiched nano-film composed of two 2D rectangular prisms arrays and two glass substrates with a continuous film in between is examined to enhance the transmission of the continuous silver film.
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Date Issued: 2018
Identifier: CFE0007117, ucf:51943
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007117

Title: Catalyst Design and Mechanism Study with Computational Method for Small Molecule Activation.
Creator: Liu, Muqiong, Zou, Shengli, Harper, James, Dixon, Donovan, Chen, Gang, Feng, Xiaofeng, University of Central Florida
Abstract / Description: Computational chemistry is a branch of modern chemistry that utilizes the computers to solve chemical problems. The fundamental of computational chemistry is Schr(&)#246;dinger equation. To solve the equation, researchers developed many methods based on Born-Oppenheimer Approximation, such as Hartree-Fock method and DFT method, etc. Computational chemistry is now widely used on reaction mechanism study and new chemical designing.In the first project described in Chapter 3, we designed...
Show moreComputational chemistry is a branch of modern chemistry that utilizes the computers to solve chemical problems. The fundamental of computational chemistry is Schr(&)#246;dinger equation. To solve the equation, researchers developed many methods based on Born-Oppenheimer Approximation, such as Hartree-Fock method and DFT method, etc. Computational chemistry is now widely used on reaction mechanism study and new chemical designing.In the first project described in Chapter 3, we designed phosphine oxide modified Ag3, Au3 and Cu3 nanocluster catalysts with DFT method. We found that these catalysts were able to catalyze the activation of H2 by cleaving the H-H bond asymmetrically. The activated catalyst-2H complex can be further used as reducing agent to hydrogenate CO molecule to afford HCHO. The mechanism study of these catalysts showed that the electron transfer from electron-rich metal clusters to O atom on the phosphine oxide ligand is the major driving force for H2 activation. In addition, different substituent groups on phosphine oxide ligand were tested. Both H affinity of metal and the substituent groups on ligand can both affect the activation energy.Another project described in Chapter 4 is the modelling of catalyst with DFT. We chose borane/NHC frustrated Lewis pair (FLP) catalyzed methane activation reaction as example to establish a relationship between activation energy and catalysts' physical properties. After performing simulation, we further proved the well-accepted theory that the electron transfer is the main driving force of catalysis. Furthermore, we were able to establish a linearivrelationship for each borane between activation energy and the geometrical mean value of HOMO/LUMO energy gap (?EMO). Based on that, we introduced the formation energy of borane/NHC complex (?EF) and successfully established a generalized relationship between Ea and geometrical mean value of ?EMO and ?EF. This model can be used to predict reactivity of catalysts.
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Date Issued: 2018
Identifier: CFE0007343, ucf:52112
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007343

Title: DESIGN OF HIGH EFFICIENCY BRUSHLESS PERMANENT MAGNET MACHINES AND DRIVER SYSTEM.
Creator: He, Chengyuan, Wei, Lei, Sundaram, Kalpathy, Zhou, Qun, Jin, Yier, Zou, Shengli, University of Central Florida
Abstract / Description: The dissertation is concerned with the design of high-efficiency permanent magnet synchronous machinery and the control system. The dissertation first talks about the basic concept of the permanent magnet synchronous motor (PMSM) design and the mathematics design model of the advanced design method. The advantage of the design method is that it can increase the high load capacity at no cost of increasing the total machine size. After that, the control method of the PMSM and Permanent magnet...
Show moreThe dissertation is concerned with the design of high-efficiency permanent magnet synchronous machinery and the control system. The dissertation first talks about the basic concept of the permanent magnet synchronous motor (PMSM) design and the mathematics design model of the advanced design method. The advantage of the design method is that it can increase the high load capacity at no cost of increasing the total machine size. After that, the control method of the PMSM and Permanent magnet synchronous generator (PMSG) is introduced. The design, simulation, and test of a permanent magnet brushless DC (BLDC) motor for electric impact wrench and new mechanical structure are first presented based on the design method. Finite element analysis based on the Maxwell 2D is built to optimize the design and the control board is designed using Altium Designer. Both the motor and control board have been fabricated and tested to verify the design. The electrical and mechanical design are combined, and it provides an analytical IPMBLDC design method and an innovative and reasonable mechanical dynamical calculation method for the impact wrench system, which can be used in whole system design of other functional electric tools. A 2kw high-efficiency alternator system and its control board system are also designed, analyzed and fabricated applying to the truck auxiliary power unit (APU). The alternator system has two stages. The first stage is that the alternator three-phase outputs are connected to the three-phase active rectifier to get 48V DC. An advanced Sliding Mode Observer (SMO) is used to get an alternator position. The buck is used for the second stage to get 14V DC output. The whole system efficiency is much higher than the traditional system using induction motor.
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Date Issued: 2018
Identifier: CFE0007334, ucf:52135
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007334

Title: Time-Resolved Phosphorescence Spectroscopy at Cryogenic Temperatures for the Environmental Analysis of Polycyclic Aromatic Sulfur Heterocycles in Oil Contaminated Sites.
Creator: Al Tameemi, Maha, Campiglia, Andres, Zou, Shengli, Harper, James, Heider, Emily, Coffey, Kevin, University of Central Florida
Abstract / Description: The large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas...
Show moreThe large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). A classic example is the analysis of the sixteen polycyclic aromatic hydrocarbons included in the priority pollutants list of the U.S. Environmental Protection Agency (EPA-PAHs).This dissertation tackles a different aspect of environmental analysis as is focuses on the photoluminescence spectroscopy of polycyclic aromatic sulfur heterocycles (PASHs). Since considering the EPA-PAHs alone can lead to drastic underestimations of potential toxic effects of oil spills, a strong case can be made for including hetero-aromatic compounds in risk assessments of contaminated sites. PASHs exist in an even greater variety of chemical structures than PAHs and, because of the asymmetry imposed by the heteroatom, the number of PASHs isomers is usually large. The existence of numerous isomers of the same molecular weight increases the difficulty of separation and identification by chromatographic methods.This dissertation demonstrates the capability to differentiate individual PASHs isomers of MW 234 g mol-1 via vibrational spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2K) temperatures. Fluorescence and phosphorescence spectra are presented for isomer determination at the parts-per-billion (ng. mL-1) concentration levels. It is demonstrated that the relatively long phosphorescence decays of PASHs facilitate the time discrimination of strong fluorescence.interference from PAHs and methylated-PAHs often present in Normal-Phase HPLC fractions. The spectral and lifetime databases compiled in this dissertation have paved the road to explore the full dimensionality of photoluminescence spectroscopy.
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Date Issued: 2017
Identifier: CFE0007275, ucf:52183
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007275

Title: Thermo- and Zero-Valent Iron-Activated Persulfate Oxidation of 3,5,6-Trichloro-2-pyridinol in an Aquatic System.
Creator: Mogharbel, Roaa, Yestrebsky, Cherie, Beazley, Melanie, Zou, Shengli, Legron-Rodriguez, Tamra, Randall, Andrew, University of Central Florida
Abstract / Description: The compound 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of the broad-spectrumorganophosphorous insecticide chlorpyrifos, is both more persistent and more water soluble thanits parent compound. This difference, which allows TCPy to more readily leach into surface waterand groundwater, has led to widespread contamination of TCPy in soils and aquatic environments.In this study, the degradation of TCPy by sulfate radicals was evaluated using zero valent ironactivatedpersulfate systems and...
Show moreThe compound 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of the broad-spectrumorganophosphorous insecticide chlorpyrifos, is both more persistent and more water soluble thanits parent compound. This difference, which allows TCPy to more readily leach into surface waterand groundwater, has led to widespread contamination of TCPy in soils and aquatic environments.In this study, the degradation of TCPy by sulfate radicals was evaluated using zero valent ironactivatedpersulfate systems and heat activated persulfate system in aqueous media. Responsesurface methodology coupled with Box-Behnken design was applied in these studies to evaluatethe effects of the independent variables on the mineralization of TCPy by both systems. In eachsystem, the interactions, coefficients, and residuals of these variables were statically evaluated byAnalysis of variance. Results indicate that both systems can effectively oxidized TCPy in water.While ZV/PS exhibited a high mineralization rate of TCPy up to 81.1%, TCPy was completelymineralized in heat activated PS system. The reaction kinetics of the degradation process wereexamined as functions of experimental parameters in each system and the result revealed that theoxidation of TCPy in both systems followed a pseudo-first-order model under all conditions tested.Radical scavenging tests indicated that sulfate radicals are the predominated species in zero valentiron activated persulfate system, whereas hydroxyl radicals are the predominated species in heatactivated persulfate system. The presence of chloride, sulfate and phosphate anions showednegligible effects on TCPy oxidation by heat activated PS system. The degradation pathways ofTCPy were proposed based on the products identified by GC-MS. Calculated ?G values usingdensity functional theory agreed with the proposed experimental pathway.
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Date Issued: 2018
Identifier: CFE0007762, ucf:52386
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007762

Title: Improved system for fabrication and characterization of nanophotonic devices by multi-photon lithography.
Creator: Sharma, Rashi, Kuebler, Stephen, Zou, Shengli, Huo, Qun, Beazley, Melanie, Phanstiel, Otto, University of Central Florida
Abstract / Description: A new system for multi-photon lithography (MPL) was developed and used to fabricate three-dimensional (3D) structures with higher aspect ratio, better resolution, improved fidelity, and reduced structural distortion relative to a conventional implementation of MPL.A set of curved waveguides (Rbend = 19 (&)#181;m, and 38 (&)#181;m) and straight waveguides (length = 50 (&)#181;m, Rbend = ?) were fabricated in an epoxide photopolymer and optically characterized using light having a wavelength in...
Show moreA new system for multi-photon lithography (MPL) was developed and used to fabricate three-dimensional (3D) structures with higher aspect ratio, better resolution, improved fidelity, and reduced structural distortion relative to a conventional implementation of MPL.A set of curved waveguides (Rbend = 19 (&)#181;m, and 38 (&)#181;m) and straight waveguides (length = 50 (&)#181;m, Rbend = ?) were fabricated in an epoxide photopolymer and optically characterized using light having a wavelength in vacuum of ?0 = 2.94 (&)#181;m. The optical performance of the waveguides was compared to novel spatially-variant photonic crystals (SVPCs) previously studied in the group. The waveguides were found to guide light with 90% lower efficiency, due to mode leakage. The study provides further evidence that SVPCs operate not through total internal reflection, but rather through self-collimation, as designed.3D uniform-lattice photonic crystals (ULPCs) were fabricated by MPL using a commercial acrylate photopolymer. The ULPCs were optically characterized at ?0 = 1.55 (&)#181;m. A laser beam with adjustable bandwidth was used to measure the self-collimation in the ULPCs. For the low bandwidth beam, vertically polarized light was self-collimated, whereas horizontally polarized light diverged. The transmission efficiency of the ULPCs was also measured as a function of fill factor. The ULPC having a fill factor of 48% exhibited 80% transmission.An etching process was also developed for non-destructively removing Au/Pd coatings that must be deposited onto structures to image them by scanning electron microscopy. The structural and optical integrity of the samples was found to be maintained despite etching. The sputter-coated sample sustained no structural damage when exposed to the ?0 = 1.55 (&)#181;m. However, the metal coating resulted in diminished transmission efficiency due to the high reflection of the 1.55 (&)#181;m beam by the metal coating.
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Date Issued: 2018
Identifier: CFE0007767, ucf:52380
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007767

Title: Magnesium-based treatment for the degradation of octachlorodibenzofuran and trinitrotoluene.
Creator: Mogharbel, Amal, Yestrebsky, Cherie, Beazley, Melanie, Zou, Shengli, Legron-Rodriguez, Tamra, Randall, Andrew, University of Central Florida
Abstract / Description: The aim of the present research is to investigate the efficacy of using ball-milled zero-valent magnesium (ZVMg) with and without activated carbon (AC) for the dechlorination of polychlorinated dibenzofurans. Three different solvent systems are presented here which are ethanol, ethanol/ethyl lactate (90:10), and 2-butoxyethanol. These solvents in combination with ZVMg with and without activated carbon were tested towards the degradation of octachlorodibenzofuran (OCDF, the most highly...
Show moreThe aim of the present research is to investigate the efficacy of using ball-milled zero-valent magnesium (ZVMg) with and without activated carbon (AC) for the dechlorination of polychlorinated dibenzofurans. Three different solvent systems are presented here which are ethanol, ethanol/ethyl lactate (90:10), and 2-butoxyethanol. These solvents in combination with ZVMg with and without activated carbon were tested towards the degradation of octachlorodibenzofuran (OCDF, the most highly chlorinated PCDF congener). All the tested systems were very powerful and reductively dechlorinated OCDF to less chlorinated congeners. However, the system of ball-milled ZVMg and ethanol was the only system which converted OCDF and all byproducts to dibenzofuran, the chlorine- free compound. Kinetic results for all the studied systems fit a pseudo-first-order decay model with respect to OCDF degradation. A detailed study of the formed byproducts during the dechlorination process and a proposed degradation pathway for OCDF are present in this research. The systems consisting of ZVMg and ZVMg/AC in acidified ethanol and acidified 2-butoxyethanol were examined towards the degradation of the low-chlorinated congener 2,8-dichlorodibenzofuran. This compound was degraded efficiently in all systems. The addition of activated carbon enhanced the degradation kinetics of 2,8-dichlorodibenzofuran degradation. Another study using ZVMg and ZVMg/AC in acidified ethanol was conducted to evaluate the efficiency of the system towards the remediation of the explosive contaminant trinitrotoluene (TNT). Both systems were effective in the degradation of TNT and the reactions were found to follow pseudo-first-order kinetics. A plausible degradation pathway is proposed in this study based on the identified degradation products.
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Date Issued: 2018
Identifier: CFE0007761, ucf:52374
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007761

Title: Coated Quantum Dots: Engineering of Surface Chemistry for Biomedical and Agricultural Applications.
Creator: Maxwell, Tyler, Santra, Swadeshmukul, Gesquiere, Andre, Harper, James, Zou, Shengli, Leon, Lorraine, University of Central Florida
Abstract / Description: Quantum dots (QDs) are crystalline nanoparticles made from semiconductor material with sizes ranging from 1 to 10 nm in diameter. QDs are attractive fluorophores for bioimaging and sensing due to their size-dependent optical properties, broad absorption bands, high extinction coefficients and superior photostability. The combination of imaging and drug delivery in a single particle can provide valuable information and improve the efficacy of existing treatments. This dissertation highlights...
Show moreQuantum dots (QDs) are crystalline nanoparticles made from semiconductor material with sizes ranging from 1 to 10 nm in diameter. QDs are attractive fluorophores for bioimaging and sensing due to their size-dependent optical properties, broad absorption bands, high extinction coefficients and superior photostability. The combination of imaging and drug delivery in a single particle can provide valuable information and improve the efficacy of existing treatments. This dissertation highlights the use of QDs for biomedical and agricultural applications. Chapter 1 of this dissertation presents a background of QDs and outlines the synthesis methods of producing and functionalizing QDs. A discussion of the advantages and limitations of each method for producing water-soluble QDs and the rationale for the proposed research is also presented. Chapter 2 describes an activatable QD design for tracking of drug delivery for cancer treatment. QDs synthesized by microemulsion (ME) were cross-linked in a one-step procedure. Enhanced binding affinity of the probe to cell lines overexpressing folate receptors was shown through fluorescence microscopy. However, this system is not practical for the large-scale synthesis due to its complexity and can not be translated for clinical development. Chapter 3 presents a sol-gel synthesis method for producing water-soluble QDs utilizing the thiol-based small molecule capping agent as the stabilizer as an alternative to ME technique. This method was designed to be a simple (one-step), cost-effective, and scalable for making both manganese doped CdS and ZnS QDs. QDs were synthesized through sol-gel method with a library of organic thiol coatings and characterized by size, surface charge, stability, and optical properties. These particles were compared to QDs produced from ME synthesis and were found to have similar properties. Chapter 4 reports the sol-gel QDs as slow-release antibiotic delivery system for application as agricultural bactericide. Utilizing electrostatic interactions, the QDs were shown to be capable of improving the leaf adhesion and slowing the rate of release of streptomycin. Chapter 5 presents a summary of the major findings of this research and discusses the future research directions.
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Date Issued: 2019
Identifier: CFE0007681, ucf:52476
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007681

Title: The Schr(&)#246;dinger Equation with Coulomb Potential Admits no Exact Solutions.
Creator: Toli, Ilia, Zou, Shengli, Harper, James, Heider, Emily, Chen, Gang, Schulte, Alfons, University of Central Florida
Abstract / Description: We prove that the Schr(&)#246;dinger equation with the electrostatic potential energy expressed by the Coulomb potential does not admit exact solutions for three or more bodies. It follows that the exact solutions proposed by Fock are flawed. The Coulomb potential is the problem. Based on the classical (non-quantum) principle of superposition, the Coulomb potential of a system of many particles is assumed to be the sum of all the pairwise Coulomb potentials. We prove that this is not accurate...
Show moreWe prove that the Schr(&)#246;dinger equation with the electrostatic potential energy expressed by the Coulomb potential does not admit exact solutions for three or more bodies. It follows that the exact solutions proposed by Fock are flawed. The Coulomb potential is the problem. Based on the classical (non-quantum) principle of superposition, the Coulomb potential of a system of many particles is assumed to be the sum of all the pairwise Coulomb potentials. We prove that this is not accurate. The Coulomb potential being a hyperbolic (not linear) function, the superposition principle does not apply.The Schr(&)#246;dinger equation as studied in this PhD dissertation is a linear partial differential equation with variable coefficients. The only exception is the Schr(&)#246;dinger equation for the hydrogen atom, which is a linear ordinary differential equation with variable coefficients. No account is kept of the spin or the effects of the relativity.New electrostatic potentials are proposed for which the exact solutions of the Schr(&)#246;dinger equation exist. These new potentials obviate the need for the three-body force interpretations of the electrostatic potential.Novel methods for finding the exact solutions of the differential equations are proposed. Novel proof techniques are proposed for the nonexistence of the exact solutions of the differential equations, be they ordinary or partial, with constant or variable coefficients. Few novel applications of the established approximate methods of the quantum chemistry are reported. They are simple from the viewpoint of the quantum chemistry, but have some important aerospace engineering applications.
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Date Issued: 2019
Identifier: CFE0007733, ucf:52422
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007733

Title: Photochemistry and Applications of Diels-Alder Adducts and Photoacids in Materials Science.
Creator: Johns, Valentine, Liao, Yi, Miles, Delbert, Zou, Shengli, Gesquiere, Andre, Su, Ming, University of Central Florida
Abstract / Description: Utilizing light as an energy source for reactions has intrigued many chemists. This has led to the development of the principles of photochemistry. The Photo retro Diels Alder (PrDA) reaction is one such system that has potential for use in materials science as well as in the life sciences. However, there was no guide to predict whether a compound could undergo the PrDA reaction, which limits the widespread use of this reaction. Another system is that of photoacids (molecules that release...
Show moreUtilizing light as an energy source for reactions has intrigued many chemists. This has led to the development of the principles of photochemistry. The Photo retro Diels Alder (PrDA) reaction is one such system that has potential for use in materials science as well as in the life sciences. However, there was no guide to predict whether a compound could undergo the PrDA reaction, which limits the widespread use of this reaction. Another system is that of photoacids (molecules that release protons upon irradiation reversibly). Since most fundamental processes involve proton transfer, these types of photoacids have great potential which is yet to be explored. This thesis describes the design and synthesis of various aromatic DA adducts. These adducts were made to undergo the rDA reaction using UV (Ultra-Violet) light. Experimental results showed that the photoreactivity of these adducts depends on the electron-donating ability of the diene component and the electron-withdrawing ability of the dienophile component. In addition, mechanistic study of this reaction revealed the formation of a charge separated intermediate with a singlet excited state. The potential of the PrDA reaction was also explored in two ways. One was by designing isomeric DA adducts from pentacene and TCNE (tetracyanoethylene) which are capable of switching from one isomer to another via a PrDA process. The other way was the design and synthesis of a polymer with an anthracene diketone moeity which could undergo a PrDA reaction to change from an insulator to a semiconductor. Finally, the syntheses of a number of photoacids which not only become acidic upon irradiation but also respond to visible light reversibly have been explored. A rationale has been developed for the design of photoacids with desired photo-induced response. While electron donating and accepting groups in strategic positions help tune the pH; using different combinations of ethanol and water affect the rate of the forward and the backward processes. A photoacid monomer was also incorporated into three photoacid polymers which respond to visible light reversibly, hence promising widespread applications of these photoacids.
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Date Issued: 2012
Identifier: CFE0004556, ucf:49235
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004556

Title: Self-assembly of Amyloid Aggregates Simulated with Molecular Dynamics.
Creator: Berhanu, Workalemahu, Masunov, Artem, Kolpashchikov, Dmitry, Ye, Jingdong, Zou, Shengli, Schulte, Alfons, University of Central Florida
Abstract / Description: ABSTRACTAmyloids are highly ordered cross-? sheet aggregates that are associated with many diseases such as Alzheimer's, type II diabetes and prion diseases. Recently a progress has been made in structure elucidation, environmental effects and thermodynamic properties of amyloid aggregates. However, detailed understanding of how mutation, packing polymorphism and small organic molecules influence amyloid structure and dynamics is still lacking. Atomistic modeling of these phenomena with...
Show moreABSTRACTAmyloids are highly ordered cross-? sheet aggregates that are associated with many diseases such as Alzheimer's, type II diabetes and prion diseases. Recently a progress has been made in structure elucidation, environmental effects and thermodynamic properties of amyloid aggregates. However, detailed understanding of how mutation, packing polymorphism and small organic molecules influence amyloid structure and dynamics is still lacking. Atomistic modeling of these phenomena with molecular dynamics (MD) simulations holds a great promise to bridge this gap. This Thesis describes the results of MD simulations, which provide insight into the effects of mutation, packing polymorphism and molecular inhibitors on amyloid peptides aggregation. Chapter 1 discusses the structure of amyloid peptides, diseases associated with amyloid aggregation, mechanism of aggregation and strategies to treat amyloid diseases. Chapter 2 describes the basic principles of molecular dynamic simulation and methods of trajectory analysis used in the Thesis. Chapter 3 presents the results of the study of several all-atom molecular dynamics simulations with explicit solvent, starting from the crystalline fragments of two to ten monomers each. Three different hexapeptides and their analogs produced with single glycine replacement were investigated to study the structural stability, aggregation behavior and thermodynamics of the amyloid oligomers. Chapter 4 presents multiple molecular dynamics (MD) simulation of a pair polymorphic form of five short segments of amyloid peptide. Chapter 5 describes MD study of single-layer oligomers of the full-length insulin with a goal to identify the structural elements that are important for insulin amyloid stability, and to suggest single glycine mutants that may improve formulation. Chapter 6 presents the investigation of the mechanism of the interaction of polyphenols molecules with the protofibrils formed by an amyloidogenic hexapeptide fragment (VQIVYK) of Tau peptide by molecular dynamics simulations in explicit solvent. We analyzed the trajectories of the large (7(&)#215;4) aggregate with and without the polyphenols.Our MD simulations for both the short and full length amyloids revealed adding strands enhances the internal stability of wildtype aggregates. The degree of structural similarity between the oligomers in simulation and the fibril models constructed based on experimental data may explain why adding oligomers shortens the experimentally observed nucleation lag phase of amyloid aggregation. The MM-PBSA free energy calculation revealed nonpolar components of the free energy is more favorable while electrostatic solvation is unfavorable for the sheet to sheet interaction. This explains the acceleration of aggregation by adding nonpolar co-solvents (methanol, tri?uoroethanol, and hexa?uoroisopropanol). Free energy decomposition shows residues situated at the interface were found to make favorable contribution to the peptide -peptide association.The results from the simulations might provide both the valuable insight for amyloid aggregation as well as assist in inhibitor design efforts. First, the simulation of the single glycine mutants at the steric zipper of the short segments of various pathological peptides indicates the intersheet steric zipper is important for amyloid stability. Mutation of the side chains at the dry steric zipper disrupts the sheet to sheet packing, making the aggregation unstable. Thus, designing new peptidomimetic inhibitors able to prevent the fibril formation based on the steric zipper motif of the oligomers, similar to the ones examined in this study may become a viable therapeutic strategy. The various steric zipper microcrystal structures of short amyloid segments could be used as a template to design aggregation inhibitor that can block growth of the aggregates. Modification of the steric zipper structure (structure based design) with a single amino acid changes, shuffling the sequences, N- methylation of peptide amide bonds to suppress hydrogen bonding ability of NH groups or replacement with D amino acid sequence that interact with the parent steric zipper could be used in computational search for the new inhibitors. Second, the polyphenols were found to interact with performed oligomer through hydrogen bonding and induce conformational change creating an altered aggregate. The conformational change disrupts the intermolecular amyloid contact remodeling the amyloid aggregate. The recently reported microcrystal structure of short segments of amyloid peptides with small organic molecules could serve as a pharamcophore for virtual screening of aggregation inhibitor using combined docking and MD simulation with possible enhancement of lead enrichment. Finally, our MD simulation of short segments of amyloids with steric zipper polymorphism showed the stability depends on both sequence and packing arrangements. The hydrophilic polar GNNQQNY and NNQNTF with interface containing large polar and/or aromatic side chains (Q/N) are more stable than steric zipper interfaces made of small or hydrophobic residues (SSTNVG, VQIVYK, and MVGGVV). The larger sheet to sheet interface of the dry steric zipper through polar Q/N rich side chains was found to holds the sheets together better than non Q/N rich short amyloid segments. The packing polymorphism could influence the structure based design of aggregation inhibitor and a combination of different aggregation inhibitors might be required to bind to various morphologic forms of the amyloid peptides.
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Date Issued: 2011
Identifier: CFE0004088, ucf:49131
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004088

Title: Electrochemical Studies of Nanoscale Composite Materials as Electrodes in PEM Fuel Cells.
Creator: Anderson, Jordan, Zhai, Lei, Blair, Richard, Hampton, Michael, Zou, Shengli, Seal, Sudipta, University of Central Florida
Abstract / Description: Polymer electrolyte membrane fuel cells (PEMFCs) have recently acquired much attention as alternatives to combustion engines for power conversion. The primary interest in fuel cell technology is the possibility of 60% power conversion efficiency as compared to the 30% maximum theoretical efficiency limited to combustion engines and turbines. Although originally conceived to work with hydrogen as a fuel, difficulties relating to hydrogen storage have prompted much effort in using other fuels....
Show morePolymer electrolyte membrane fuel cells (PEMFCs) have recently acquired much attention as alternatives to combustion engines for power conversion. The primary interest in fuel cell technology is the possibility of 60% power conversion efficiency as compared to the 30% maximum theoretical efficiency limited to combustion engines and turbines. Although originally conceived to work with hydrogen as a fuel, difficulties relating to hydrogen storage have prompted much effort in using other fuels. Small organic molecules such as alcohols and formic acid have shown promise as alternatives to hydrogen in PEMFCs due to their higher stability at ambient conditions. The drawbacks for using these fuels in PEMFCs are related to their incomplete oxidation mechanisms, which lead to the production of carbon monoxide (CO). When carbon monoxide is released in fuel cells it binds strongly to the platinum anode thus limiting the adsorption and subsequent oxidation of more fuel. In order to promote the complete oxidation of fuels and limit poisoning due to CO, various metal and metal oxide catalysts have been used.Motivated by promising results seen in fuel cell catalysis, this research project is focused on the design and fabrication of novel platinum-composite catalysts for the electrooxidation of methanol, ethanol and formic acid. Various Pt-composites were fabricated including Pt-Au, Pt-Ru, Pt-Pd and Pt-CeO2 catalysts. Electrochemical techniques were used to determine the catalytic ability of each novel composite toward the electrooxidation of methanol, ethanol and formic acid. This study indicates that the novel composites all have higher catalytic ability than bare Pt electrodes. The increase in catalytic ability is mostly attributed to the increase in CO poison tolerance and promotion of the complete oxidation mechanism of methanol, ethanol and formic acid. Formulations including bi- and tri-composite catalysts were fabricated and in many cases show the highest catalytic oxidation, suggesting tertiary catalytic effects. The combination of bi-metallic composites with ceria also showed highly increased catalytic oxidation ability. The following dissertation expounds on the relationship between composite material and the electrooxidation of methanol, ethanol and formic acid. The full electrochemical and material characterization of each composite electrode is provided.
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Date Issued: 2012
Identifier: CFE0004510, ucf:49264
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004510

Title: Investigating New Guaiazulenes and Diketopyrropyrroles for Photonic Applications.
Creator: Ghazvini Zadeh, Ebrahim, Belfield, Kevin, Campiglia, Andres, Yuan, Yu, Zou, Shengli, Cheng, Zixi, University of Central Florida
Abstract / Description: ?-Conjugated systems have been the focus of study in recent years in order to understand their charge transport and optical properties for use in organic electronic devices, fluorescence bioimaging, sensors, and 3D optical data storage (ODS), among others. As a result, several molecular building blocks have been designed, allowing new frontiers to be realized. While various successful building blocks have been fine-tuned at both the electronic and molecular structure level to provide advanced...
Show more?-Conjugated systems have been the focus of study in recent years in order to understand their charge transport and optical properties for use in organic electronic devices, fluorescence bioimaging, sensors, and 3D optical data storage (ODS), among others. As a result, several molecular building blocks have been designed, allowing new frontiers to be realized. While various successful building blocks have been fine-tuned at both the electronic and molecular structure level to provide advanced photophysical and optoelectronic characteristics, the azulene framework has been under-appreciated despite its unique electronic and optical properties. Among several attributes, azulenes are vibrant blue naturally occurring hydrocarbons that exhibit large dipolar character, coupled with stimuli-responsive behavior in acidic environments. Additionally, the non-toxic nature and the accompanying eco-friendly feature of some azulenes, namely guaiazulene, may set the stage to further explore a more (")green(") route towards photonic and conductive materials.The first part of this dissertation focuses on exploiting guaiazulene as a natural building block for the synthesis of chromophores with varying stimuli-responsiveness. Results described in Chapter 1 show that extending the conjugation of guaiazulene through its seven-membered ring methyl group with aromatic substituents dramatically impacts the optical properties of the guaiazulenium carbocation. Study of these ?(-)stabilized tropilium ions enabled establishing photophysical structure-property trends for guaiazulene-terminated ?-conjugated analogs under acidic conditions, including absorption, emission, quantum yield, and optical band gap patterns. These results were exploited in the design of a photosensitive polymeric system with potential application in the field of three dimensional (3D) optical data storage (ODS).Chapter 2 describes the use of guaiazulene reactive sites (C-3 and C-4 methyl group) to generate a series of cyclopenta[ef]heptalenes that exhibit strong stimuli-responsive behavior. The approach presents a versatile route that allows for various substrates to be incorporated into the resulting cyclopenta[ef]heptalenes, especially after optimization that led to devising a one-pot reaction toward such tricyclic systems. Examining the UV-vis absorption profiles in neutral and acidic media showed that the extension of conjugation at C(4) of the cyclopenta[ef]heptalene skeleton results in longer absorption maxima and smaller optical energy gaps. Additionally, it was concluded that these systems act as sensitizers of a UV-activated ((<) 300 nm) photoacid generator (PAG), via intermolecular photoinduced electron transfer (PeT), upon which the PAG undergoes photodecomposition resulting in the generation of acid.In a related study, the guaiazulene methyl group at C-4 was employed to study the linear and nonlinear optical properties of 4-styrylguaiazulenes, having the same ?(-)donor with varying ?-spacer. It was realized that the conjugation length correlates with the extent of bathochromic shift of the protonated species. On the other hand, a trend of decreasing quantum yield was established for this set of 4-styrylguaiazulenes, which can be explained by the increasingly higher degree of flexibility.The second part of this dissertation presents a comprehensive investigation of the linear photophysical, photochemical, and nonlinear optical properties of diketopyrrolopyrrole (DPP)-based derivatives, including two-photon absorption (2PA), femtosecond transient absorption, stimulated emission spectroscopy, and superfluorescence phenomena. The synthetic feasibility, ease of modification, outstanding robustness, and attractive spectroscopic properties of DPPs have motivated their study for fluorescence microscopy applications, concluding that the prepared DPP's are potentially suitable chromophores for high resolution stimulated emission depletion (STED) microscopy.
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Date Issued: 2015
Identifier: CFE0006034, ucf:50986
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006034

Title: Synthesis and Characterization of New Probes for use in Fluorescence and X-ray CT Bioimaging.
Creator: Tang, Simon, Belfield, Kevin, Miles, Delbert, Campiglia, Andres, Zou, Shengli, Cheng, Zixi, University of Central Florida
Abstract / Description: The pursuit of more suitable drugs intended for possible biological applications are a continuously growing topic of research within the scientific community. One of these suitable qualities includes the need for hydrophilicity and or some appropriate delivery system for the drug to enter into biological systems. A system of analyzing and following these compounds would then, however, be necessary to conduct any kind of mechanistic or interaction studies for he said drug within the biological...
Show moreThe pursuit of more suitable drugs intended for possible biological applications are a continuously growing topic of research within the scientific community. One of these suitable qualities includes the need for hydrophilicity and or some appropriate delivery system for the drug to enter into biological systems. A system of analyzing and following these compounds would then, however, be necessary to conduct any kind of mechanistic or interaction studies for he said drug within the biological system. Just to name a few, fluorescence and X-ray computed tomography (CT) methods allow for imaging of biological systems but require the need of compounds with specific qualities. Finally, even with a means of entering and following a oaded drug, it would not be complete without a way of targeting its intended location. Herein, the first chapter reports the synthesis and characterization of a fluorene-based pyridil bis-?-diketone compound with suitable one- and two-photon fluorescent properties and its encapsulation into Pluronic F127 micelles for the possible application of tracking lysosomes. Next the synthesis and characterization of a BODIPY-based fluorophore with excellent fluorescence ability is reported. This compound was conjugated to two triphenylphosphine (TPP) groups and is shown as a potential mitochondria probe within HCT-116 cells. Finally, the synthesis and characterization of diatrizoic acid (DA) based derivatives conjugated to silica nanoparticles, as well as unconjugated, are reported as potential CT contrast agents. The derivatives were also functionalized with maleimide moieties facilitating subsequent potential bioconjugation of a targeting protein via a thiol group.
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Date Issued: 2015
Identifier: CFE0006056, ucf:50961
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006056

Title: Photophysics of Organic Probes and their Applications in Bioimaging (&) Photodynamic Therapy.
Creator: Kim, Bosung, Belfield, Kevin, Zou, Shengli, Campiglia, Andres, Frazer, Andrew, Ali, Gul Shad, University of Central Florida
Abstract / Description: Over the past several decades the phenomenon of luminescence (divided into fluorescence and phosphorescence) has received great attention in the field of biological science. This quest has motivated scientists for a variety of applications, including fluorescence imaging. Fluorescence microscopy techniques that provide unique advantages, such as high spatial resolution and superior sensitivity, have been regarded as attractive tools in biophotonics. With the progress of ultrafast laser...
Show moreOver the past several decades the phenomenon of luminescence (divided into fluorescence and phosphorescence) has received great attention in the field of biological science. This quest has motivated scientists for a variety of applications, including fluorescence imaging. Fluorescence microscopy techniques that provide unique advantages, such as high spatial resolution and superior sensitivity, have been regarded as attractive tools in biophotonics. With the progress of ultrafast laser sources, two-photon absorption (2PA), in which a molecule absorbs two photons simultaneously, has opened possibilities of using it for various applications. Two-photon fluorescence microscopy (2PFM), which affords deeper tissue penetration and excellent three-dimensional (3D) images, is now being widely employed for bioimaging. This dissertation focuses on the design, synthesis, and photophysical characterization of new fluorophores, as well as desirable applications. Chapter 1 gives an account of a brief introduction of luminescence and 2PA, as well as their utilities in biological applications. In chapter 2, a series of new BODIPY derivatives are presented along with their comprehensive linear and nonlinear characteristics. They exhibited excellent photophysical properties including large extinction coefficients, high fluorescence quantum yields, good photostability, and reasonable two-photon absorption cross sections. Two promising compounds were further evaluated as NIR fluorescent probes in one-photon and two-photon fluorescence imaging. Chapter 3 provides the design, synthesis, and photophysical characterization of two BODIPY dyes. In order to assess the potential of using the dye as a fluorescent probe, Lysotracker Red, a commercial lysosomal marker, was investigated for comparison purposes. The results indicate that figure of merit of both compounds were three orders of magnitude higher than that of Lysotracker Red. With an eye towards applications, one of the compounds was encapsulated in silica-based nanoparticles for in vitro and ex vivo one-photon and two-photon fluorescence imaging, in which the surface of the nanoparticle was modified with RGD peptides for specific targeting. The nanoprobe exhibited good biocompatibility and highly selective RGD-mediated uptake in ?V?3 integrin-overexpressing cancers, while maintaining efficient fluorescence quantum yield and high photostability. In chapter 4, the synthesis and photophysical properties of a novel photosensitizer with heavy atoms (halogen) were presented. The dye exhibited low fluorescence quantum yield, resulting in high singlet oxygen generation quantum yield. In vitro photodynamic studies demonstrated that photosensitization of the agent can induce cellular damage, subsequently leading to cell death by a necrotic cell death mechanism, supporting the therapeutic potential of using the agent for photodynamic therapy.
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Date Issued: 2015
Identifier: CFE0006041, ucf:50977
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006041

Two-Photon Absorption (3)	+ -
Computational Chemistry (2)	+ -
DFT (2)	+ -
Discrete Dipole Approximation (2)	+ -
Photoacid (2)	+ -

Two-photon absorption (2)	+ -
nanoparticle (2)	+ -
two-photon absorption (2)	+ -
waveguides (2)	+ -
2D Materials (1)	+ -
3 (1)	+ -
5 (1)	+ -
6-trichloro-2-pyridinol (1)	+ -
Activated carbon (1)	+ -
Amyloid fibril (1)	+ -
Azulene (1)	+ -
BODIPY (1)	+ -
Ball-milled zero-valent magnesium (1)	+ -
Beta sheet inhibitor (1)	+ -
Bioimaging (1)	+ -
Biosensors (1)	+ -
Catalysis (1)	+ -
Ceramic nanofibers (1)	+ -
Chemo Hydrothermally Treated (1)	+ -
Chitin (1)	+ -
Chitosan (1)	+ -
Computational chemistry (1)	+ -
Conductive Ceramics (1)	+ -
Continuous metal film (1)	+ -
Copper-Chitosan (1)	+ -

ETD Collection (38)	+ -
Honors Collection (1)	+ -

University of Central Florida (39)	+ -
Zou, Shengli (39)	+ -
Campiglia, Andres (11)	+ -
Harper, James (9)	+ -
Belfield, Kevin (8)	+ -

Frazer, Andrew (8)	+ -
Zhai, Lei (8)	+ -
Yestrebsky, Cherie (6)	+ -
Gesquiere, Andre (5)	+ -
Kolpashchikov, Dmitry (5)	+ -
Beazley, Melanie (4)	+ -
Cheng, Zixi (4)	+ -
Chumbimuni Torres, Karin (4)	+ -
Huo, Qun (4)	+ -
Kuebler, Stephen (4)	+ -
Chen, Gang (3)	+ -
Heider, Emily (3)	+ -
Hernandez, Florencio (3)	+ -
Liao, Yi (3)	+ -
Miles, Delbert (3)	+ -
Randall, Andrew (3)	+ -
Su, Ming (3)	+ -
Ye, Jingdong (3)	+ -
Bhattacharya, Aniket (2)	+ -
Blair, Richard (2)	+ -
Clausen, Christian (2)	+ -
Coffey, Kevin (2)	+ -
Khondaker, Saiful (2)	+ -
Legron-Rodriguez, Tamra (2)	+ -
Masunov, Artem (2)	+ -

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