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1
Mathew, Anoop. "Interfacial phenomena in high-kappa dielectrics." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 118 p, 2009. http://proquest.umi.com/pqdweb?did=1654501721&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Kim, Philseok. "Surface modification of nanoparticles for polymer/ceramic nanocomposites and their applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31651.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Perry, Joseph W.; Committee Member: Kippelen, Bernard; Committee Member: Lyon, L. Andrew; Committee Member: Marder, Seth R.; Committee Member: Whetten, Robert L. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Insin, Numpon. "Surface modifications of iron oxide nanoparticles for biological applications." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62723.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Page 192 blank. Vita. Cataloged from PDF version of thesis, 2011.
Includes bibliographical references.
Iron oxides magnetic nanoparticles (MPs) of high crystallinity, high magnetization, and size-monodispersity were synthesized with oleic acid as their native ligands. These hydrophobic and non-functionalized MPs have magnetic properties that are suitable for various biological applications. Surface modifications were studied for transferring these MPs into biological environments as well as transforming them into functional nanoparticles. Certain surface modifications of MPs, such as attaching silane groups and silica coating, lead to formation of more complex structures of superparamagnetic and fluorescent silica microspheres and nanostructures. These microspheres and nanostructures comprising MPs and semiconductor quantum dots (QDs) are useful tools for biological applications such as for magnetically controlling with fluorescent tracking of particles and for bimodal imaging. Surface modifications of MPs with hydrophobically-modified polyacrylic acid (mPAA) amphiphilic polymer and catechol-derivative surfactants resulted in hydrophilic MPs that are stable in physiological environment and small in their hydrodynamic size. These MPs are also designed to possess active functional groups that are necessary for further conjugations with proteins and molecules of interest. These hydrophilic and functional MPs are useful in biological applications such as magnetic resonance imaging and sensing applications.
by Numpon Insin.
Ph.D.
4
Wang, Hui. "DESIGN, SYNTHESIS, AND SUPRAMOLECULAR SURFACE CHEMISTRY OF BI- AND TRIDENTATE SURFACE ANCHORS FOR NANOSCIENCE AND NANOBIOTECHNOLOGY." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1185474081.
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Arvizo, Rochelle R. "Applying surface modified gold nanoparticles to biological systems." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/dissertations/AAI3372254/.
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Kist, Madelyn M. "Light-induced surface site manipulation of gold nanoparticles using diazonium salt." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1626960076521484.
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Petroski, Janet Marie. "Platinum metal nanoparticles : investigation of shape, surface, catalysis and assembly." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30961.
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Kaur, Inder Preet. "Understanding the surface chemistry of ceria nanoparticles using a multi-method approach." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6388/.
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Ceria nanoparticles (NPs), due to their widespread applications, have attracted a lot of concern about their toxic effects on both human health and environment. Cerium occurs in two oxidation states, Ce (III) and Ce (IV), and has the unique ability to readily switch between these two states. There is a lot of speculation on the redox behaviour of cerium oxide being related to its toxicity but there are large gaps in knowledge of whether Ce (III) or Ce (IV) is responsible for such toxic behaviours, their toxicological mechanism and safety assessment. The aim of this study is to accurately quantify the ratio of Ce (III) and Ce (IV) in synthesised ceria samples using a multi-method approach thus providing an insight in understanding their surface chemistry and hence biological behaviour. Ceria NPs of different shapes and sizes were produced with different strengths of interaction between core and capping agent/no capping agent and with both steric and charge stabilization. The oxidation state of the samples was determined using STEM-EELS and XPS. Later in the study, we investigated the uptake and internalisation of different shapes and sizes of ceria NPs in lung-derived A549 cell lines (Adenocarcinomic human alveolar basal epithelial cells, A549).
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Millsaps, Caitlin. "Deposition of platinum particles on surface-modified carbon ultramicroelectrodes." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/honors/639.
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Nanoparticles are used as electrocatalysts due to their large surface area-to-volume ratios. Most studies of nanoparticle electrocatalysis are performed on collections of particles on a support, which represent ensemble average behavior influenced by spatial distribution of the nanoparticles. Therefore, recent emphasis has been placed on analyzing electrocatalytic behavior of single particles. The focus here is to develop carbon ultramicro- and nanoelectrode platforms for studying the electrocatalytic properties of single metal nanoparticles. Ultramicroelectrodes were prepared using chemical vapor deposition of carbon in pulled quartz capillaries. Electrode diameters were determined by cyclic voltammetry. Electrodes were modified using a soft nitriding technique to enable immobilization of platinum nanoparticles through reduction of H2PtCl6 using NaBH4. Cyclic voltammetry was used to determine the presence of platinum particles through characteristic peaks associated with Pt oxide formation and reduction. Ultimately, these electrodes could be used to analyze single uncapped nanoparticles to understand the electrochemical properties of single nanoparticles.
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Jayalath, Mudiyanselage Sanjaya Dilantha. "Surface adsorption of natural organic matter on engineered nanoparticles." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6440.
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Nanoparticles have gained growing attention of the scientific community over the past few decades due to their high potential to be used in diverse industrial applications. Nanoparticles often possess superior characteristics, such as catalytic activity, photochemical activity, and mechanical strength, compared to their bulk counterparts, making them more desirable in different industrial applications. During the past few decades, the use of the nanoparticles in various industries has been increased. With increasing usage release of nanoparticles into the environment has also increased. There is a growing concern about the nanoparticle toxicity and numerous studies have shown the toxic effects of different nanoparticles on various plants, animals, and microorganisms in the environment. Toxicity of nanoparticles is often attributed to their morphology and their ability to undergo different transformations in the environment. These transformations include aggregation, dissolution, and surface adsorption.
Natural organic matter (NOM) are the most abundant natural ligands in the environment which include Humic acid and Fulvic acid. These high molecular weight organic molecules have complex structures and contain many different functional groups such as carboxylic acid groups, hydroxyl, amino and phenolic groups that can interact with the nanoparticle surface. The nature and the intensity of the interaction are dependent on several factors including the size and the surface functionality of nanoparticles and pH of the medium. The smaller the nanoparticle, the higher the adsorption of NOM due to the high surface to volume ratio of smaller particles. Functional groups on the surface dictate the surface charge of the nanoparticles in water depending on the acidity. The higher the acidity, higher the adsorption of NOM due to increased electrostatic attractions between positively charged nanoparticles and the negatively charged NOM molecules. Adsorbed NOM on nanoparticles affect the other transformations such as aggregation and dissolution and can in turn alter the reactivity and toxicity of the nanoparticles. Therefore, effect of NOM is an important factor that should be considered in environmental toxicity related studies of nanoparticles.
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Gruenbaum, Scott M. "The Fluorescence Enhancement Effects of Gold Nanoparticles." Miami University Honors Theses / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1115239158.
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Hammond, Stephen Peter. "Imaging of luminescent nanoparticles in flows : development of surface active luminescent lanthanide complexes." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/1235/.
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We have developed a new ligand (H\(_3\)L\(^2\)) based on a DTPA bis-amide backbone which improves upon previous work within the group. The quantum yields of the europium and samarium complexes of H\(_3\)L\(^2\) are greatly enhanced over that of H\(_3\)L\(^1\). The previously observed nanoparticle-based quenching of the lanthanide luminescence lifetime of EuL\(^1\) is suppressed in EuL\(^2\). We have demonstrated the functionalisation of gold and platinum nanoparticles of various sizes with the surface active lanthanide complexes of H\(_3\)L\(^1\) and H\(_3\)L\(^2\). As a proof of principle, we have imaged, tracked and measured velocities of individual EuL\(^2\) functionalised nanoparticles in an aqueous flow, providing flow-rates accurate to micrometer resolution of fluids through a 2 mm diameter tube. We have also observed the microscale mixing of a nanoparticle labelled solution with water on time-scales of milliseconds to seconds. We can study the development and measure the dimensions of features present during mixing and therefore assess the efficiency of that mixing. We have also visualised a turn-on event at the boundary of aqueous solutions of Eu(III) ions and H\(_3\)L\(^2\)-functionalised nanoparticles during mixing, demonstrating a novel optical method for ascertaining the degree of mixing between two solutions and the position and area of that mixing.
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Duguay, Dominique R. "Cellular imaging through functionalized carborane-containing silver nanoparticles utilizing surface enhanced Raman scattering spectroscopy." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28490.
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This thesis focuses on various carborane compounds and their uses for targeted cellular imaging. Cellular imaging agents have been developed for the field of medical diagnosis and treatment for some time. Many different processes have been traditionally applied in these fields, including fluorescence tagging, but these are lacking in differentiation from cellular background signals. Herein, carborane compounds have been developed for use as Raman reporters with signature absorption for BH vibrations, inside of the cell silence vibrational range. Carboranes have also been studied for the application of Boron Neutron Capture Therapy, a binary radiation therapy technique. Coupling these two ideas has lead to the formation of specific cellular targeting agents utilizing the unique BH vibrations for imaging, as well as the possible application of BNCT to the malignant tissue. This process has been developed with the aid of silver nanoparticles, which have been shown to enhance the Raman signal up to a factor of 1014 with Surface Enhanced Raman Scattering (SERS) techniques. Functionalized carborane compounds have been developed in order to study BH vibrations, and carborane-containing functionalized silver nanoparticles have been applied to target anti-EGFR antibodies for malignant tissue detection. Resulting SERS images confirmed selective tissue targeting with nanoparticle aggregate hot spots. Overlaying scanning electron microscope images with SERS BH vibrational intensity maps provided additional information on concentrations of cell surface receptors and identifying intercellular structures. Elaboration of the carborane Raman reporter resulted in two other carboranes with key functional groups, which could increase solubility, and have additional Raman handles for identification.
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Zemke, Jennifer M. 1983. "Surface Modification and Multiple Exciton Generation Studies of PbS Nanoparticles." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/12085.
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xx, 134 p. : ill. (some col.)Solar energy is a green alternative to fossil fuels but solar technologies to date have been plagued by low conversion efficiencies and high input costs making solar power inaccessible to much of the developing world. Semiconductor nanoparticles (NPs) may provide a route to efficient, economical solar devices through a phenomenon called multiple exciton generation (MEG). Through MEG, semiconductor NPs use a high-energy input photon to create more than one exciton (electron-hole pair) per photon absorbed, thereby exhibiting large photoconversion efficiencies. While MEG has been studied in many NP systems, and we understand some of the factors that affect MEG, a rigorous analysis of the NP-ligand interface with respect to MEG is missing. This dissertation describes how the NP ligand shell directly affects MEG and subsequent charge carrier recombination. Chapter I describes the motivation for studying MEG with respect to NP surface chemistry. Chapter II provides an in-depth overview of the transient absorption experiment used to measure MEG in the NP samples. Chapter III highlights the effect of oleic acid and sodium 2, 3-dimercaptopropane sulfonate on MEG in PbS NPs. The differences in carrier recombination were accounted for by two differences between these ligands: the coordinating atom and/or the secondary structure of the ligand. Because of these hypotheses, experiments were designed to elucidate the origin of these effects by controlling the NP ligand shell. Chapter IV details a viable synthetic route to thiol and amine-capped PbS NPs using sodium 3-mercaptopropane sulfonate as an intermediate ligand. With the versatile ligand exchange described in Chapter IV, the MEG yield and carrier recombination was investigated for ligands with varying headgroups but the same secondary structure. The correlation of ligand donor atom to MEG is outlined in Chapter V. Finally, Chapter VI discusses the conclusions and future outlook of the research reported in this dissertation. This dissertation includes previously published and unpublished co-authored material.
Committee in charge: Dr. Geraldine L. Richmond, Chairperson; Dr. David R. Tyler, Advisor; Dr. Mark C. Lonergan, Member; Dr. Catherine J. Page, Member; Dr. Hailin Wang, Outside Member
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Siriwardane, Induni Wathsala. "Adsorption of citric acid on cerium oxide nanoparticles (nanoceria) : effects of pH, surface charge and aggregation." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3385.
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Among a large number of engineered nanomaterials, CeO2 nanoparticles (nanoceria) are of particular interest due to their unique oxidative, optical and electrical properties. With the increasing use of this important rare-earth metal oxide nanoparticle, there is the potential for it to be released in to the environment. Surface adsorbed ligands affect the surface chemistry of nanomaterials and thereby ultimately determining their fate and transformation in the natural environment. Citric acid is a naturally abundant organic acid, which can play an important role in determining the environmental fate of nanomaterials. This study focuses on citric acid adsorption onto nanoceria for three different particle diameters of 4, 9 and 39 nm. Both the details of surface adsorption of citric acid at different pH and its impact on nanoparticle behavior are explored.Speciation of adsorbed citric acid as a function of pH is probed using ATR–FTIR measurements, whereas HPLC and X–ray photoelectron spectroscopy are used to quantify the adsorption coverage. These results show that the surface speciation of citric acid differs from that of bulk solution in all pHs studied and the coordination to the surface as well as surface coverage is a function of particle size. Nanoparticle–nanoparticleinteractions and suspension stabilities are further probed through sedimentation and zeta potential measurements to better understand the behavior of ceria nanoparticles with and without the presence of citric acid.
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Ono, Luis. "IN-SITU GAS PHASE CATALYTIC PROPERTIES OF METAL NANOPARTICLES." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3277.
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Recent advances in surface science technology have opened new opportunities for atomic scale studies in the field of nanoparticle (NP) catalysis. The 2007 Nobel Prize of Chemistry awarded to Prof. G. Ertl, a pioneer in introducing surface science techniques to the field of heterogeneous catalysis, shows the importance of the field and revealed some of the fundamental processes of how chemical reactions take place at extended surfaces. However, after several decades of intense research, fundamental understanding on the factors that dominate the activity, selectivity, and stability (life-time) of nanoscale catalysts are still not well understood. This dissertation aims to explore the basic processes taking place in NP catalyzed chemical reactions by systematically changing their size, shape, oxide support, and composition, one factor at a time. Low temperature oxidation of CO over gold NPs supported on different metal oxides and carbides (SiO2, TiO2, TiC, etc.) has been used as a model reaction. The fabrication of nanocatalysts with a narrow size and shape distribution is essential for the microscopic understanding of reaction kinetics on complex catalyst systems ("real-world" systems). Our NP synthesis tools are based on self-assembly techniques such as diblock-copolymer encapsulation and nanosphere lithography. The morphological, electronic and chemical properties of these nanocatalysts have been investigated by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD). Chapter 1 describes briefly the basic principles of the instrumentation used within this experimental dissertation. Since most of the state-of-art surface science characterization tools provide ensemble-averaged information, catalyst samples with well defined morphology and structure must be available to be able to extract meaningful information on how size and shape affect the physical and chemical properties of these structures. In chapter 2, the inverse-micelle encapsulation and nanosphere lithography methods used in this dissertation for synthesizing uniformly arranged and narrow size- and shape-selected spherical and triangular NPs are described. Chapter 3 describes morphological changes on individual Au NPs supported on SiO2 as function of the annealing temperature and gaseous environment. In addition, NP mobility is monitored. Chapter 4 explores size-effects on the electronic and catalytic properties of size-selected Au NPs supported on a transition metal carbide, TiC. The effect of interparticle interactions on the reactivity and stability (catalyst lifetime) of Au NPs deposited on TiC is discussed in chapter 5. Size and support effects on the formation and thermal stability of Au2O3, PtO and PtO2 on Au and Pt NPs supported on SiO2, TiO2 and ZrO2 is investigated in chapter 6. Emphasis is given to gaining insight into the role of the NP/support interface and that played by oxygen vacancies on the stability of the above metal oxides. Chapter 7 reports on the formation, thermal stability, and vibrational properties of mono- and bimetallic AuxFe1-x (x = 1, 0.8, 0.5, 0.2, 0) NPs supported on TiO2(110). At the end of the thesis, a brief summary describes the main highlights of this 5-year research program.Ph.D.
Department of Physics
Sciences
Physics PhD
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Al, Minshid Alaa Hani Naser. "Surface chemistry of metal oxide nanoparticles in biological and environmental media of varying pH." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6359.
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Investigate the interaction of nanomaterials with biological systems, known as nano-bio interaction is of great interest for the assessment of the concern arising from nanomaterials progressive use. Such interaction determines nanomaterials potential effect on human and environment becomes more and more important to understand how they interact with living organisms and the environment. The novel physicochemical characteristics of nanomaterials, such as their small size, large surface area to volume ratio and surface energy, may initiate new toxicological effects due to nanomaterials ability to enter into the biological systems through adsorption and dissolution and modify the structure of various macromolecules An example of these interactions is the adsorption of proteins on nanoparticles surface forming what is known as the 'protein corona'. Therefore, being able to understand how these molecules and other biologically important species are adsorbed and interact, should help us to reduce any adverse impacts of nanoparticles on human health and the environment.
Due to the importance of surface composition and surface functionality in nanotoxicology, analytical tools that can probe the change in the structure and composition of the nanoparticles in aqueous media are crucial but remain limited. Therefore in this work, in situ characterization of the liquid–solid interface to probe surface adsorption of environmentally and biologically relevant media on nanoparticle surfaces has been conducted. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy provides the molecular information that allows for the determination of the adsorption mode such as conformational and structural changes of the coordinating ligand. Surface adsorption of titanium dioxide (TiO2) nanoparticles have been investigated in different biological media typically used for toxicity studies and show that the surface composition of TiO2 nanoparticles depends to a large extent on the composition of the medium due to surface adsorption. Moreover, hydrodynamic diameter and surface charge of TiO2 NPs were evaluated using dynamic light scattering DLS. The results indicated that TiO2 NPs undergo different trends in aggregation upon the adsorption of biological media on its surface and zeta potential measurements showed surface charge alterations which are consistent with the aggregation study.
In order to understand the dynamic transformations of nanomaterials in biological environments, the effect of dissolution has been predicted. Copper oxide CuO and zinc oxide ZnO nanoparticles were used to study dissolution due to their instability in biological media. Once these particles exposed to solutions they release their ions and tend to aggregate. Therefore, the dissolution of these materials was conducted at size ca. 24 nm and nanoparticles coated with proteins and humic acid employing simulated lung fluids as models to develop a better understanding of how these properties effect the solubility and stability in biological systems. From this study, it was found that both copper oxide and zinc oxide NPs showed different trends in dissolution. Cu and Zn ions once coated with proteins and HA highly dissolved in ALF at low pH 4.5 compared with other fluids (Gamble’s solution and water) at extracellular pH which shows only slightly enhanced in the basal condition. The acidity of ALF may explain the higher solubility of metals that are phagocytized versus those that remain extracellular. Some general conclusions can be drawn from these investigations. It seems that analytical tools to characterize the interfacial region between nanopaerticles and these complex systems provide a reasonably good qualitative and quantitative description of the interactions.
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Sun, Ying. "A Multi-Method Approach for the Quantification of Surface Amine Groups on Silica Nanoparticles." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39480.
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As nanomaterials continue to garner interest in a wide range of industries and
scientific fields, commercial suppliers have met growing consumer demand by readily
offering custom particles with size, shape and surface functionality made-to-order. By
circumventing the challenging and complex synthesis of functionalized nanoparticles,
these businesses seek to provide greater access for the experimentation and
application of these nanoscale platforms.
In many cases, amine functional groups are covalently attached as a surface
coating on a nanoparticle to provide a starting point for chemical derivatization and
commonly, conjugation of biomolecules in medical science applications. Successful
conjugation can improve the compatibility, interfacing and activity of therapeutic and
diagnostic nanomedicines. Amines are amongst the most popular reactive groups used
in bioconjugation pathways owing to the many high-yield alkylation and acylation
reaction are involved in.
For the design of functionalized nanomaterials with precisely tuned surface
chemical properties, it is important to develop techniques and methods which can
accurately and reproducibly characterize these materials. Quantification of surface
functional groups is crucial, as these groups not only allow for conjugation of chemical
species, but they also influence the surface charge and therefore aggregation behavior
of nanomaterials. The loss of colloidal stability of functionalized nanomaterials can often
correspond to a significant if not complete loss of functionality.
Thus, we sought to develop multiple characterization approaches for the
quantification of surface amine groups. Silica nanoparticles were selected as a model
nanomaterial as they are widely used, commercially available, and their surface
chemistry has been investigated and studied for decades. Various commercial batches
of silica nanoparticles were procured with sizes ranging from 20 – 120 nm. Two
colorimetric assays were developed and adapted for their ease-of-use, sensitivity, and
convenience. In addition, a fluorine labelling technique was developed which enabled
analysis by quantitative solid-state 19F NMR and X-ray photoelectron spectroscopy
(XPS). XPS provided data on surface chemical composition at a depth of ≈ 10 nm,
which allowed us to determine coupling efficiencies of the fluorine labelling technique
and evaluate the reactivity of the two assays.
The ensemble of surface-specific quantification techniques was used to evaluate
multiple commercial batches of aminated silica and investigate batch-to-batch variability
and the influence of particle size with degree of functionalization. In addition, resulting
measurements of surface amine content were compared and validated by an
independent method based on quantitative solution 1H NMR, which was developed for
total functional group content determination. This allowed for us to assess the role of
accessibility and reactivity of the amine groups present in our silica particles.
Overall, the objective of this study was to develop a multi-method approach for
the quantification of amine functional groups on silica nanoparticles. At the same time,
we hoped to set a precedent for the development and application of multiple
characterization techniques with an emphasis of comparing them on the basis of
reproducibility, sensitivity, and mutual validation.
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Glogowski, Elizabeth M. "Nanoparticle functionalization and grafting-from chemistry for controlling surface properties and nanocomposite behavior." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/dissertations/AAI3349701/.
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Stepanek, C. J. "Surface labelling of gold nanoparticles with inorganic lumophores and targeting vectors for cell imaging applications." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7800/.
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Transition metal complexes are attractive imaging probes as they offer distinctive photophysical, electrochemical and synthetic advantages over organic dyes, quantum dots and fluorescent proteins due to their high photo-stability, long luminescence lifetimes and large Stokes shifts. Gold nanoparticles have also revolutionised the design, delivery and functionality of imaging probes, being attractive scaffolds to bind luminescent complexes, targeting vectors and therapeutic substances. Previous work in the group has demonstrated that gold nanoparticles can be efficiently coated with transition metal complexes, with the resulting coated particles useful in cellular imaging. In this work, a water-soluble luminescent ruthenium complex and pH-low insertion peptides (pHLIPs) were coupled to gold nanoparticles, and these labelled-nanoparticles exhibited enhanced uptake into human cervical adenocarcinoma cells. The mechanism of pHLIP-mediated nanoparticle delivery was investigated, by conducting time and pH resolved experiments, with an interest in contrasting the benefits of two pHLIP variants as nanoparticle delivery vectors. Subsequent investigations revealed the concentration of intracellular glutathione imposed an effect on nanoparticle internalisation efficiency and the colloidal stability of labelled gold nanoparticles, and that providing gold nanoparticles with a hydrophobic lipid coating also enhanced the efficiency of nanoparticle internalisation into cells.
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Qu, Haiou. "Surface Functionalized Water-Dispersible Magnetite Nanoparticles: Preparation, Characterization and the Studies of Their Bioapplications." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1536.
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Iron oxide magnetic nanoparticle synthesis and their surface functionalization hold a crucial position in the design and fabrication of functional materials for a variety of biomedical applications. Non-uniform nanoparticles with poor crystallinity, prepared by conventional methods, have only limited value in biological areas. Large scale synthesis methods that are able to produce high quality, mono-dispersed iron oxide nanoparticles using low cost and environment friendly chemicals are highly desirable. Following synthesis, appropriate surface functionalization is necessary to direct the dispersibility of nanoparticles in aqueous solution in order to provide them with acceptable colloidal stability against the ion strength and many biomolecules that nanoparticles may encounter under physiological conditions. Poorly stabilized nanoparticles that easily aggregate and form large size agglomerates would be quickly cleared by the liver and other organs and are not suitable for clinical purposes. Additionally, many interesting functionalities such as fluorescence, targeting and anti-cancer properties can be immobilized onto the surface of iron oxide magnetic nanoparticles during the surface functionalization process so as to build multifunctional platforms for disease diagnosis and treatment.
Polyol method can be an effective way to prepare magnetite nanoparticles that are suitable for biological applications. In a polyol system, selected surface functionalities were introduced to the nanoparticle surface via a hot injection technique. The morphology, uniformity, crystallinity and magnetic properties were examined to understand the effect of different ligand molecules on the final product. Their surface chemistry, colloidal properties and surface reactivity were also studied to evaluate their practicability in different applications.
A high efficiency in-situ method for the preparation of magnetite nanoparticles attached to silica nanospheres was also developed in a polyol system. This approach eliminates several time-consuming processing steps that are in the conventional fabrication route and directly produces water-stable magnetite-silica hybrid materials with surface availability for subsequent modifications.
In addition to polyalcohol, the potential of polyamine in the preparation of water-soluble magnetite nanoparticles with amine surface functionalities was also evaluated. And it is suggested that polyamine acts as solvent, stabilizing agent and reducing agent simultaneously during the synthesis. The characterization of polyamine coated nanoparticles, their surface functionalization, and subsequent application for bioseparation and drug delivery were reported.
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Eteer, Shahrazad A. "The physical chemistry of corticosteroid-cyclodextrin complexes: The Host-guest Chemistry of Corticosteroid and Cyclodextrin Systems Elucidated with NMR and Applied to Novel Surface-decorated Surface Enhanced Raman Spectroscopic Probes." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17379.
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Inhaled corticosteroids (ICS) are used to address inflammatory illnesses including asthma and COPD, with delivery commonly achieved using pressurised metered dose inhalers (pMDI). Hydrofluoroalkanes (HFAs) have been introduced as an alternative propellant to chlorofluorocarbons (CFCs) to reduce their environmental impact. However, the thermodynamic properties of HFAs are poorly understood and are different to those of CFCs. It is essential, therefore, to characterise the drugs and excipients used in HFA inhalers in order to obtain a comprehensive understanding of the device performance and the therapeutic efficacy.
This work has developed different analytical methods to study the complexation between ICS and CD which are added to enhance the solubility of inhaled drugs in pMDI propellant systems providing rational control of suspension vs. solution formulations and hence their dose uniformity and stability.
The Nuclear Magnetic Resonance (NMR) method developed has shown weaker complexation between budesonide and the derivatised CDs DIMEB and TRIMEB in organic solvents compared to D2O with the strength of the complex formed being ranked as D2O > MeOD > CDCl3 > CD3CN. The derivatisation of the CD also shows a marked difference in complexation with budesonide with the strength of the association being ranked as DIMEB > βCD > TRIMEB. Studies of various ICS compounds with TRIMEB in the fluorinated propellant HPFP showed the association to be greatest in budesonide, followed by beclomethasone dipropionate, momestasone furoate and fluticasone propionate.
Surface-enhanced Raman scattering (SERS) has been used for the detection of corticosteroids in water using thiol functionalised βCD as a complementary study to NMR. This has been utilised to evaluate the host-guest complexes formed and provides further insight into the complexation of the compounds by their inclusion into the CD cavity.
The structural data obtained using the NMR and SERS approaches developed have provided a fundamental insight into the physical chemistry of these interactions at a molecular level.
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Gilliland, Stanley E. III. "Synthesis, Surface Functionalization, and Biological Testing of Iron Oxide Nanoparticles for Development as a Cancer Therapeutic." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4024.
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Iron oxide nanoparticles are highly researched for their use in biomedical applications such as drug delivery, diagnosis, and therapy. The inherent biodegradable and biocompatible nanoparticle properties make them highly advantageous in nanomedicine. The magnetic properties of iron oxide nanoparticles make them promising candidates for magnetic fluid hyperthermia applications. Designing an efficient iron oxide nanoparticle for hyperthermia requires synthetic, surface functionalization, stability, and biological investigations. This research focused on the following three areas: optimizing synthesis conditions for maximum radiofrequency induced magnetic hyperthermia, designing a simple and modifiable surface functionalization method for specific or broad biological stability, and in vitro and in vivo testing of surface functionalized iron oxide nanoparticles in delivering effective hyperthermia or radiotherapy.
The benzyl alcohol modified seed growth method of synthesizing iron oxide nanoparticles using iron acetylacetonate as an iron precursor was investigated to identify significant nanoparticle properties that effect radiofrequency induced magnetic hyperthermia. Investigation of this synthesis under atmospheric conditions revealed a combination of thermal decomposition and oxidation-reduction mechanisms that can produce nanoparticles with larger crystallite sizes and decreased size distributions.
Nanoparticles were easily surface functionalized with (3-Glycidyloxypropyl)trimethoxysilane (GLYMO) without the need for organic-aqueous phase transfer methods. The epoxy ring on GLYMO facilitated post-modifications via a base catalyzed epoxy ring opening to obtain nanoparticles with different terminal groups. Glycine, serine, γ-aminobutryic acid (ABA), (S)-(-)-4-amino-2-hydroxybutyric acid (SAHBA), ethylenediamine, and tetraethylenepentamine were successful in modifying GLYMO coated-iron oxide nanoparticles to provide colloidal and varying biological stability while also allowing for further conjugation of chemotherapeutics or radiotherapeutics. The colloidal stability of cationic and anionic nanoparticles in several biologically relevant media was studied to address claims of increased cellular uptake for cationic nanoparticles.
The surface functionalized iron oxide nanoparticles were investigated to determine effects on cellular uptake and viability. In vitro tests were used to confirm the ability of iron oxide nanoparticles to provide effective hyperthermia treatment. S-2-(4-Aminobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid (DOTA) was coupled to SAHBA and carboxymethylated polyvinyl alcohol surface functionalized iron oxide nanoparticles and radiolabeled with 177Lu. The capability of radiolabeled iron oxide nanoparticles for delivering radiation therapy to a U87MG murine orthotopic xenograft model of glioblastoma was initially investigated.
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Badwaik, Vivek D. "Single-Step Biofriendly Synthesis of Surface Modifiable, Near-Spherical Gold Nanoparticles for Applications in Biological Detection and Catalysis." TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/1092.
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There is an increased interest in understanding the toxicity and rational design of gold nanoparticles (GNPs) for biomedical applications in recent years. Such efforts warrant reliable, viable, and biofriendly synthetic methodology for GNPs with homogeneous sizes and shapes, particularly sizes above 30 nm, which is currently challenging. In the present study, an environmentally benign, biofriendly, singlestep/ single-phase synthetic method using dextrose as a reducing and capping agent in a buffered aqueous solution at moderate temperature is introduced. The resulting GNPs are near-spherical, stable, catalytically active, place exchangeable, and water-soluble within the size range of 10-120 nm. The added advantage of the biologically friendly reaction medium employed in this new synthetic approach provides a method for the direct embedment/integration of GNPs into biological systems such as the E. coli bacterium without additional capping ligand or surface modification processes.
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Joo, Minjung. "Silane terminated macromonomers with nanoparticles and surface segregation of fluorinated moieties." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1478876813425998.
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Hong, Seongmin. "Optimization, Modification and Application of Gold Nanoparticles as the Substrates of Surface Enhanced Raman Spectroscopy." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4819.
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Dotse, Charles Kafui. "ELECTROCHEMICAL AND SURFACE-ENHANCED RAMAN SPECTROSCOPIC STUDIES OF FORMIC ACID OXIDATION, CARBON MONOXIDE AND 1, 4-PHENYLENEDIISOCYANIDE ADSORPTION ON METAL NANOPARTICLES." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1451993102.
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Jean, Deok-im. "CORE-SHELL NANOPARTICLES: SYNTHESIS, ASSEMBLY, AND APPLICATIONS." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1374848575.
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Vabbilisetty, Pratima. "Functional Anchoring Lipids for Drug Delivery Carrier Fabrication and Cell Surface Re-Engineering Applications." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1424175323.
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Glover, Richard. "Utilizing Platforms for the Observation of Chemical Transformations to Surface-Bound Noble Metal Nanoparticles in Environmentally Relevant Conditions." Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/12998.
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Nanoparticles are increasingly incorporated into consumer products because of their unique, size-dependent properties. Although these properties are commercially appealing, data are lacking regarding the fate and reactivity of nanoparticles once incorporated into materials. This information gap prevents accurate assessment of hazards that these materials potentially present to consumers and the environment. To address this concern, new research is needed to investigate the reactivity and transformations of nanoparticles.
This dissertation describes the use of an electron transparent characterization platform to observe nanoparticle transformations. Nanoparticles were tethered to the surface of an analysis platform, exposed to a variety of conditions, and evaluated for reactivity and response. The characterization of silver nanoparticles revealed the generation of new daughter nanoparticles on surfaces in ambient humid conditions. Our observations showed that the transport of material is highly dependent on relative humidity and that pH equilibria drives the deposition of new particles and degradation. We discovered, by applying these findings to macro-silver objects, that bulk silver generates new nanoparticles on surfaces. This illuminated the possibility of other, yet undiscovered, naturally occurring nanoparticles.
In the second model system, 1.5 nm gold nanoparticles were tethered by a robust metal oxide bond from the terminal group of the stabilizing ligand. This strategy facilitated precise control over thiol ligand removal using a dilute ozone oxidation. Tracking particle oxidation over time allowed us to gain unprecedented control over core exposure, size maintenance, and surface tethering.
This platform was also utilized as a proof-of-concept for direct observation of transformations in complex media. Ligand and core transformations were monitored in a variety of biologically relevant conditions using tethered nanoparticles. Morphological and chemical transformations were characterized and correlated to results from solution monitoring.
The use of a platform based approach to evaluating the reactivity of nanoparticles in the environment holds promise for evaluations of nanoparticles and their transformation products. The demonstration of monitoring reactivity in systems equilibria, carefully controlled transformations, or complex media shows the versatility of this strategy. Only through the use of this analysis platform was the direct observation of nanoparticle transformations possible.
This dissertation includes previously published, unpublished, and co-authored materials.10000-01-01
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Dirlam, Philip Thomas. "The Preparation of Functional Surfaces." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/588.
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Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates in reversible manner. Glass slides and capillaries were functionalized with hydrophobic dieneophiles resulting in a non-wetting surface. A retro Diels-Alder reaction facilitated by the thermal treatment of the surface’s function to cleave the hydrophobic dieneophile and resulted in the fabrication of a hydrophilic surface. Contact angle (CA) measurements were used as preliminary measurements for monitoring the changes in surface energy exhibited during the initial hydrophobic state (CA - 70±3°), after attachment of the dieneophile creating a hydrophobic state (CA - 101±9°) followed by reestablishment of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder adduct. The treatments developed on flat glass surfaces were transferred to glass capillaries, with effective treatment confirmed by fluid column measurements. Effective flow gating was developed in the capillaries via patterning of the surface with hydrophilic/hydrophobic regions. Finally, attempts to create self-pressurizing capillaries were unsuccessful due to pronounced contact angle hysteresis for the hydrophobic surface treatment.
Indium-tin oxide (ITO) substrates were functionalized with successive surface intiated atom transfer radical polymerization (SI-ATRP) and electropolymerization. A novel hybrid styrenic/thiophene monomer (ProDOT-Sty) was synthesized and employed in the polymerization events. This unique monomer and combination of polymerization methods allowed for the templation of electropolymerized poly(3,4-alkyleneoxythiophene) brushes by first creating a poly(styrene) backbone via SI-ATRP. An ITO electrode functionalized with poly(ProDOT-Sty) brushes grafted from the ITO surface via SI-ATRP was analyzed via cyclic voltammetry which clearly indicated the electropolymerization event beginning at approximately +0.7 V vs Fc/Fc+. Photo patterning of the phosphonic acid ATRP initiator immobilized on the ITO surface was undertaken in order to create a surface that would limit growth of the polymer species to a patterned area for facile film brush thickness characterization via atomic force microscopy (AFM) at a later time. This was accomplished via lithography with ultraviolet radiation (UV) and was confirmed via scanning electron microscopy (SEM).
A nanohetero structure composed of platinum tipped cadmium selenide seeded, cadium sulfide nanorods (CdSe@CdS-Pt NRs). CdSe quantum dots (QDs) with variable sizes were prepared by adjusting reaction temperatures and times. CdS nanorods were then grown utilizing the CdSe QDs as seeds. Various lengths of the CdSe@CdS NRs were produced that ranged from ~25 nm to ~135 nm. Investigation of the influence of the various synthetic conditions of the nanorod synthesis led to the conclusion that the ratio of CdSe seeds to Cd and S precursors could be manipulated in order to influence the length to which the nanorods grew. Pt tips were attached to an end of the CdSe@CdS nanorods as photocatalytic hydrogen production sites. TEM was utilized to characterize the different types of nanoparticles at each stage of assembly.
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Pirani, Parisa. "Surface-Engineered Magnetic Nanoparticles for Sample Preparation and Analysis of Proteins and Peptides." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2012.
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Sample preparation as an essential step in mass spectrometry-based analysis, plays a critical role in proteomics studies. Magnetic nanoparticles (MNPs) have been widely used in protein and peptide sample preparation due to their magnetic properties, biocompatibility, easy synthesis and surface functionalization. MNPs loaded with analyte or analyte modification reagent can be easily separated from the reaction medium by an externally applied magnetic field. The small size of MNPs provides high analyte loading and extraction capacity. Additionally, MNP can be decorated with different functional groups to achieve selective modification or extraction of analyte. In this study we have utilized silica coated iron oxide magnetic nanoparticles (Fe3O4@SiO2 MNPs) for protein and peptide sample preparation.
Fluorescence-based methods were utilized for quantitative and qualitative characterization of N-hydrosucccinimidyl (NHS) ester groups on the surface of Fe3O4@SiO2 MNPs. Fluorophore Dansylcadaverine was conjugated to NHS ester functional groups. Fluorometric measurement of cleaved dansylcadaveine was employed to determine the number of NHS ester groups per MNPs that was found to be 2.6 × 102 and 3.4 × 103for 20 nm and 100 nm Fe3O4@SiO2 MNPrespectively. The efficiency of labeling native bovine serum albumin (BSA) by NHS ester coated Fe3O4@SiO2 MNPs was also explored in terms of maximizing the number of MNPs conjugated per BSA molecule or maximizing the number of BSA molecules conjugated per each MNP.
Lysine residues of apolipoprotein B-100 (apoB-100) on the surface of intact human low density lipoprotein (LDL) were labeled by NHS ester modified Fe3O4@SiO2 MNPs in aqueous solvents at room temperature. The MNP labeledapoB-100 was treated by SDS to remove lipids and then digested using trypsin. Tryptic peptides were eluted from MNPs by cleaving disulfide linkage between labeled peptides and MNPs. LC-MS/MS analysis found 28 peptides containing labeled lysine residues. These lysine residues should be on the solvent exposed surface of LDL since the large size of MNPs prevents contact of the labeling reagent to those lysines embedded inside the structure of LDL.
TCEP- immobilized Fe3O4@SiO2MNPs were fabricated and utilized for reduction of disulfide bonds in bovine pancreas insulin and two different cyclic peptides. Disulfide bonds were efficiently cleaved at room temperature in both organic and aqueous solvents confirmed by LC-MS/MS analysis of reduced/alkylated protein and peptides. Disulfide reduction and alkylation reactions was performed in one step and the reducing agent was simply separated from peptide and protein solution by magnetic separation.
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Kairdolf, Brad A. "Development of polymer-coated nanoparticle imaging agents for diagnostic applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31845.
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Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Nie, Shuming; Committee Member: Bao, Gang; Committee Member: Murthy, Niren; Committee Member: Varma, Vijay; Committee Member: Wang, Zhong Lin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Shen, Christopher. "Effects of surface chemistry and size on iron oxide nanoparticle delivery of oligonucleotides." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39520.
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The discovery of RNA interference and the increasing understanding of disease genetics have created a new class of potential therapeutics based on oligonucleotides. This therapeutic class includes antisense molecules, small interfering RNA (siRNA), and microRNA modulators such as antagomirs (antisense directed against microRNA) and microRNA mimics, all of which function by altering gene expression at the translational level. While these molecules have the promise of treating a host of diseases from neurological disorders to cancer, a major hurdle is their inability to enter cells on their own, where they may render therapeutic effect. Nanotechnology is the engineering of materials at the nanometer scale and has gained significant interest for nucleic acid delivery due to its biologically relevant length-scale and amenability to multifunctionality. While a number of nanoparticle vehicles have shown promise for oligonucleotide delivery, there remains a lack of understanding of how nanoparticle coating and size affect these delivery processes. This dissertation seeks to elucidate some of these factors by evaluating oligonucleotide delivery efficiencies of a panel of iron oxide nanoparticles with varying cationic coatings and sizes. A panel of uniformly-sized nanoparticles was prepared with surface coatings comprised of various amine groups representing high and low pKas. A separate panel of nanoparticles with sizes of 40, 80, 150, and 200 nm but with the same cationic coating was also prepared.
Results indicated that both nanoparticle surface coating and nanoparticle hydrodynamic size affect transfection efficiency. Specific particle coatings and sizes were identified that gave superior performance. The intracellular fate of iron oxide nanoparticles was also tracked by electron microscopy and suggests that they function via the proton sponge effect. The research presented in this dissertation may aid in the rational design of improved nanoparticle delivery vectors for nucleic acid-based therapy.
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Placencia, Diogenes. "Interface Studies of Small-Molecule Organic Photovoltaics; Surface Modifications, Electron Donor Texturing, and Co-Facial Variations at the Donor/Acceptor Heterojunctions." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202936.
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The role of the oxide/organic and organic/organic interfaces in small-molecule planar-Heterojunction (PHJ) photovoltaics was investigated with three interrelated projects: i) indium-tin oxide (ITO) bottom contact electrodes were modified with gold nanoparticles (Au-NPs) to improve rates of charge-transfer at the donor/oxide interface, ii) donor layers in OPVs were textured to increase charge generation at the organic/organic' interface, and iii) the effect of co-facial overlap on device performance via tuning of the electron acceptor orientation at the organic/organic interface. The modification of ITO with Au-NPs showed increased performance in small-molecule OPVs when compared to non-processed ITO devices due to the interactions between the Au-NPs and the donor material. Textured TiOPc increased overall device performance by a factor of 2X via the increased surface area, near-IR absorption, and increased mobilities. Modified and un-modified PTCDA acceptors showed that co-facial overlap at the organic/organic' interface is a large determinant in device performance, while the performance in small-molecule planar-heterojunction photovoltaics were severely affected by the pre-treatment process, most likely due to the particular interactions between the oxide and the donor material.
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Xu, Bolei. "SURFACE REACTIONS AND ULTRAFAST DYNAMICS IN NANO- AND MICRO-SIZED MATERIALS." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/404549.
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ChemistryPh.D.
In this dissertation, the laser spectroscopic methods, second harmonic generation (SHG) and ultrafast transient absorption, have been employed to study the reactions and dynamics in two different types of materials, namely, silver nanoparticles and micro-sized ultrathin crystalline oligoacenes. These two materials, although both are in small dimensions, represent two distinct types of systems with divergent characteristics: 1) systems in which interactions at the surface/interface are dominant, and 2) systems in which bulk interactions are dominant. Silver nanoparticles are an important member of the class of noble metal nanoparticles, and possess unique optical and chemical properties due to their ultrafine size and high surface-to-volume ratio. Strong SHG signal has been observed from silver nanoparticles dispersed in aqueous colloidal solution, in which the SHG signal is enhanced due to a resonance with the localized surface plasmon of silver nanoparticles. Further experiments proved that the SHG signal predominantly originates from the particle surface, in full agreement with the intrinsically interface-sensitive properties of SHG. With the surface origin of the signal now well established, SHG can be used to probe the adsorption and reactions of thiol molecules at the nanoparticle surface in situ and in real time. It is experimentally demonstrated that the free energy change, activation energy, as well as adsorption density of the reactions of a variety of neutral and anionic thiols at the particle surface can be measured by means of SHG. The reaction mechanisms at the molecular level have been deduced, and the neutral vs anionic thiols are found to exhibit qualitatively different reaction mechanisms that reflect the effect of their molecular interactions with the particle surface. Oligoacenes, such as pentacene and hexacene, constitute a family of organic semiconductors that exhibit remarkable optoelectronic properties. In contrast to the nanoparticles in which surface interactions are dominant, as the sizes of materials become larger, the bulk characteristics become more deterministic. Therefore, polarized linear absorption and transient absorption spectroscopies have been applied to study the excitonic properties of crystalline pentacene and the mechanism of singlet fission in crystalline hexacene, respectively. The polarized absorption spectra of crystalline pentacene have been obtained by measuring transmitted light normal to the ab herringbone plane of micro-sized ultrathin single crystals. The significant deviations between the spectral line shapes polarized along the b-axis and orthogonal to the b-axis provide detailed information on the anisotropic mixing nature of the Frenkel/charge-transfer excitons responsible for the pronounced Davydov splitting between the lowest-energy singlet states. Additionally, both singlet and triplet Davydov splittings were also observed from the linear and transient absorption experiments in micrometer-sized ultrathin hexacene single crystals. A two-step process of anisotropic singlet fission was uncovered from the kinetic data, in which singlet fission at different rates were deduced along the a- and b-axes. Both the spectral and kinetic features indicate that singlet fission in crystalline hexacene is an anisotropic and charge-transfer mediated many-molecule process.
Temple University--Theses
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Al-Saadi, Ali. "Preparation and characterisation of encapsulation magnetic metal iron oxide nanoparticles." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:57bdcf38-9d45-48ab-a971-a2d60e2e4391.
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One of the most challenging goals in nanoparticle research is to develop successful protocols for the large-scale, simple and possibly low-cost preparation of morphologically pure nanoparticles with enhanced properties. The work presented in this thesis was focused on the synthesis, characterisation and testing of magnetic nanoparticles and their potential applications. There are a number of magnetic nano-materials prepared for specific applications such as metal oxide nanoparticles encapsulated with various porous materials including Fe₃O₄/Fe₂O₃ coated with soft bio-organic materials such as glycol chitosan and bovine serum albumin and hard materials such as silica (SiO₂) and zinc sulphide (ZnS). The preparation of these materials was achieved principally by bottom-up methods with different approaches including micro-emulsion, precipitation, electrostatic and thermolysis processes. The thesis also presents the uses of various analytical techniques for characterising different types of nano-materials including Attenuated Total Reflection Fourier Transformer Infrared Vibrational Spectroscopy (ATR-FTIR), Ultraviolet Visible- Near Infrared (UV-Vis-NIR) Spectroscopy, Zeta Potentiometric Surface Charge Analysis, Superconducting Quantum Interference Device (SQUID) and Vibration Sample Magnetometry (VSM) for magnetic analysis and powder X-Ray Diffraction (XRD) for crystallographic pattern analysis. There are many applications of magnetic nanoparticles, including nano-carriers for biological and catalytic reagents. The magnetic nanoparticles can facilitate separation in order to isolate the carriers from solution mixtures as compared to many inefficient and expensive classic methods, which include dialysis membrane, electrophoresis, ultracentrifugation, precipitation and column separation methods. There are six key chapters in this thesis: the first chapter introduces the up-to-date literature regarding magnetic nano-materials. The uses of magnetic nano-materials in drug binding and for protein separation are discussed in the second and third chapters. The fourth chapter presents the use of magnetic nanoparticle in conjunction with a photo-catalytic porous overlayer for the photo-catalytic reduction of organic molecules. The fifth chapter describes different analytical techniques used for the characterisation of nanoparticles and the underlying principles and the experimental details are also given. The sixth chapter summarises the results and provides an overview of the work in a wider context of future applications of magnetic nanoparticles.
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Thielbeer, Frank. "Modification and use of polymeric particles for chemical biology." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7615.
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Polymeric nano and microparticles are important tools for an increasing variety of applications in the life sciences such as cellular delivery, sensing and imaging, with a fundamental requirement being particle functionalisation. Herein, the use of zeta potential measurements is described as a convenient tool to allow a variety of chemical reactions to be rapidly monitored on particles. To allow multifunctionalisations these particles need to be orthogonally modified. As part of this thesis, novel dual-functionalised aminomethyl and boronic acid particles were synthesised. These particles could be modified via amide formation and palladiummediated cross coupling, with applications demonstrated in cellular delivery and cellbased cargo release. The requirement for bright fluorescent particles for applications in the life sciences was addressed by the synthesis and analysis of particles prepared using polymerisable fluorescein derivatives. Although nanoparticles are a promising technology to solve a variety of problems, their behaviour in biological systems is not fully understood. Herein, the effects of the particle’s surface chemistry on cellular uptake and toxicity were investigated.
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Keser, Sezen Lutfiye. "Preparation Of Gold Decorated Cobalt-silica Core-shell Nanoparticles For Surface Enhanced Raman Scattering Applications." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612383/index.pdf.
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Bringing together several materials into a single nanoparticle is an attractive way to design systems that exhibit diverse physical and chemical properties. Cobalt nanoparticles are extensively used in magnetic separation, ferrofluids, and magnetic storage media. The deposition of gold nanoparticles onto cobalt core significantly affects their optical properties due to the introduction of surface Plasmon.
Here the synthesis of gold nanoparticles decorated cobalt-silica nanoparticles are reported for the first time. Their optical and magnetic properties and capacity as a surface enhanced Raman scattering (SERS) substrate were investigated. This nano-material is of particular interest as a dual agent allowing both magnetic separation and SERS detection. The synthesis involves three steps: i) synthesis of Co nanoparticlesii) deposition of a silica shell around the Co core and introduction of amine functional groups on the surface
iii) decoration of the surface with gold nanoparticles. Co nanoparticles were prepared in an inert atmosphere in the presence of capping and reducing agents. Size of the cobalt nanoparticles was varied by changing the concentration of the capping agent. Since cobalt particles are easily oxidized, they were coated with silica shell both to prevent oxidation and allow further functionalization. Silica coating of the particles were performed in water/ethanolic solution of tetraethyl orthosilicate (TEOS). Thickness of silica coating was controlled by varying the concentrations of TEOS. Besides, by adding 3-aminopropyl-triethoxysilane (APTS) to the reaction medium, primarily amine groups were introduced on the silica surface. For further modifications citrate stabilized gold nanoparticles were appended onto the surface of amine modified core-shell cobalt-silica nanoparticles. Gold decorated magnetic core-shell structures were used as SERS substrate with Raman dyes
brilliant cresyl blue (BCB) and rhodamine 6G (R6G). They were also utilized for preconcentration and SERS detection of 4-mercapto benzoic acid (4-MBA). Gold nanoparticles on the silica and thiol group on the 4-MBA were very selective to each other, thus, 4-MBA could be attached on to gold surface and it could be easily separated magnetically from the reaction medium and identified by Raman spectroscopy. Characterization of the cobalt, cobalt-silica and gold modified cobalt-silica nanoparticles was done by Field Emission Scanning Electron Microscopy (FE-SEM), Scanning-Transmission Electron Microscopy (S-TEM), Energy-Dispersive X-ray Spectroscopy (EDX), UV-Vis spectrometry, and Raman microscope system.
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Ozturk, Tacettin. "The Use Of Gold And Silver Nanoparticles For Surface Enhanced Fluorescence Of Dyes." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612389/index.pdf.
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This study focuses on preparing surface enhanced fluorescence (SEF) substrates for use in the enhancement of the emission signal of rhodamine B and fluorescein dyes.
Fluorescence spectroscopy has been widely utilized owing to its high sensitivity. SEF is a process where the interactions of fluorophores with the localized surface plasmons of metal nanoparticles results in fluorescence enhancement, increased photostability and rates of system radiative decay which leads to a decreased lifetime. One of the most important factors of SEF studies is to provide a uniform distance between fluorophore and metal nanoparticle in a controlled mannerotherwise, Fö
rster resonance energy transfer takes place from fluorophore to metal nanoparticle and emission intensity of fluorophore is quenched. The spherical gold and silver nanoparticles were prepared using the well known and straightforward chemical reduction method, in which sodium citrate acted both as a reducing agent and a stabilizer around the formed nanoparticles. Silver and gold were chosen because of their high plasmon field enhancement. Since plasmon field strongly depends on the shape and size of the nanoparticles, the prepared nanoparticles were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Prior to deposition of silver or gold nanoparticles on glass slides, the slides were derivatized by immersing them into an aqueous solution of 3-Aminopropylethoxysilane (APTES). Following derivatization, silver or gold nanoparticles were deposited by immersing the slides into the colloid mixture. Metal nanoparticle coated slides were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Surface enhanced Raman scattering (SERS) measurements were carried out to observe the plasmon efficiency of the deposited nanoparticles. The SERS measurements were repeated for the duration of two weeks in order to check the stability of the plasmon efficiency. In this study, different types of materials (silica, zinc oxide, gold, stearic acid.) were employed as spacers to observe their effects on fluorescence enhancement. Physical vapor deposition (PVD) and Langmuir-Blodgett (LB) film deposition techniques were used for the formation of the spacer within the substrate. Fluorescence enhancement of rhodamine B and fluorescein was observed on the prepared SEF substrates. Obtained enhancement factors indicate that SEF substrates have the potential for sensitivity improvements of fluorescence sensing in many fields.
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Khemtong, Chalermchai. "Synthesis and Supramolecular Chemistry of 2,4,9-Trithiaadamantane Derivatives." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1123084162.
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Jeffery, Brandon Reed. "Design and Construction of a High Vacuum Surface Analysis Instrument to Study Chemistry at Nanoparticulate Surfaces." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76776.
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Metal oxide and metal oxide-supported metal nanoparticles can adsorb and decompose chemical warfare agents (CWAs) and their simulants. Nanoparticle activity depends on several factors including chemical composition, particle size, and support, resulting in a vast number of materials with potential applications in CWA decontamination. Current instrumentation in our laboratory used to investigate fundamental gas-surface interactions require extensive time and effort to achieve operating conditions.
This thesis describes the design and construction of a high-throughput, high vacuum surface analysis instrument capable of studying interactions between CWA simulants and nanoparticulate surfaces. The new instrument is small, relatively inexpensive, and easy to use, allowing for expeditious investigations of fundamental interactions between gasses and nanoparticulate samples. The instrument maintains the sample under high vacuum (10?⁷-10?⁹ torr) and can reach operating pressures in less than one hour. Thermal control of the sample from 150-800 K enables sample cleaning and thermal desorption experiments. Infrared spectroscopic and mass spectrometric methods are used concurrently to study gas-surface interactions. Temperature programmed desorption is used to estimate binding strength of adsorbed species. Initial studies were conducted to assess the performance of the instrument and to investigate interactions between the CWA simulant dimethyl methylphosphonate (DMMP) and nanoparticulate silicon dioxide.Master of Science
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Kaya, Murat. "Preparation And Surface Modification Of Noble Metal Nanoparticles With Tunable Optical Properties For Sers Applications." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613129/index.pdf.
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Metal nanostructures exhibit a wide variety of interesting physical and chemical properties, which can be tailored by altering their size, morphology, composition, and environment. Gold and silver nanostructures have received considerable attention for many decades because of their widespread use in applications such as catalysis, photonics, electronics, optoelectronics, information storage, chemical and biological sensing, surface plasmon resonance and surface-enhanced Raman scattering (SERS) detection.
This thesis is composed of three main parts about the synthesis, characterization and SERS applications of shape-controlled and surface modified noble metal nanoparticles. The first part is related to a simple synthesis of shape controlled solid gold, hollow gold, silver, gold-silver core-shell, hollow gold-silver double-shell nanoparticles by applying aqueous solution chemistry. Nanoparticles obtained were used for SERS detection of dye molecules like brilliant cresyl blue (BCB) and crystal violet (CV) in aqueous system.
v
The second part involves the synthesis of surface modified silver nanoparticles for the detection of dopamine (DA) molecules. Determination of a dopamine molecule attached to a iron-nitrilotriaceticacid modified silver (Ag-Fe(NTA)) nanoparticles by using surface-enhanced resonance Raman scattering (SERRS) was achieved. The Ag-Fe (NTA) substrate provided reproducibility and excellent sensitivity. Experimental results showed that DA was detected quickly and accurately without any pretreatment in nM levels with excellent discrimination against ascorbic acid (AA) (which was among the lowest value reported in direct SERS detection of DA).
In the third part, a lanthanide series ion (Eu3+) containing silver nanoparticle was prepared for constructing a molecular recognition SERS substrate for the first time. The procedure reported herein, provides a simple way of achieving reproducible and sensitive SERS spectroscopy for organophosphates (OPP) detection. The sensing of the target species was confirmed by the appearance of an intense SERS signal of the methyl phosphonic acid (MPA), a model compound for nonvolatile organophosphate nerve agents, which bound to the surface of the Ag-Eu3+ nanostructure. The simplicity and low cost of the overall process makes this procedure a potential candidate for analytical control processes of nerve agents.
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Elhaj, Baddar Zeinah. "ENGINEERING ZINC OXIDE NANOPARTICLES TO BE USED AS NANOFERTILIZERS." UKnowledge, 2018. https://uknowledge.uky.edu/pss_etds/109.
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Zinc deficient soils, or soils with low Zn bioavailability, are widespread, which exacerbates Zn deficiency in human as crops grown on these soils have low Zn content. Often crop yields are also compromised. Fertilizers based on soluble Zn salts often have limited efficacy in such soils. In this research, we evaluate the performance of polymer coated and bare ZnO nanoparticles (NPs) in an attempt to overcome limitations of soluble Zn salts in alkaline soils. We first synthesized 20-30 nm bare ZnO NPs with different surface chemistries to impart colloidal stability to the particles. Bare ZnO were treated in phosphate solution under certain conditions leading to the formation of a core made of ZnO NPs that is covered by a shell of amorphous Zn3(PO4)2 (core-shell NPs). This confers a negative charge to the particles over a wide pH range. The addition of nonionic (neutral dextran) and polyelectrolyte (negatively charged dextran sulfate (DEX(SO4)) during the synthesis resulted in the formation of DEX and DEX(SO4) ZnO NPs. Dextran has a minimal effect on the surface charge of ZnO but dextran sulfate confers a net negative charge. Bare and core-shell ZnO NPs were both electrostatically stabilized whereas DEX and DEX(SO4) ZnO NPs were sterically and electrosterically stabilized, respectively. We investigated the effect of treating seeds with ZnO NPs on the growth and accumulation of Zn in wheat (Triticum aestivum) seedlings in comparison to ZnSO4. All ZnO NPs stimulated seedling growth. Seedlings accumulated higher Zn concentrations when treated with ZnO NPs than with ZnSO4. Zinc sulfate was toxic even at the lower exposure concentrations, which was demonstrated by significantly lower germination success and seedling growth. In the second experiment, we investigated the effect of pH on the attachment and dissolution of ZnO NPs in soil, as compared to ZnSO4. Soil pH was adjusted to 6 and 8, then the soil was spiked with 100 mg Zn/kg soil in the form of ZnSO4, bare, DEX, DEX(SO4), and core-shell ZnO NPs. The results showed that DEX and core-shell ZnO NPs had significantly higher total Zn in soil solution compared to ZnSO4 at pH 8, with little dissolution. Dissolved Zn was similar among treatments except ZnSO4 at pH 6, indicating little dissolution of the ZnO NPs at either pH value. We also found that the engineered coatings dictate the behavior of the particles in simple aqueous systems, but their properties are altered in natural soil solutions because of the dominant effect of natural organic matter (NOM) on their surface chemistry. Based on the outcomes of the previous two experiments, we selected DEX and bare ZnO NPs to test the efficacy of ZnO NPs in delivering Zn to the grain of wheat under greenhouse conditions. We performed two independent studies where seeds were either treated with the NPs or grown in a soil spiked with Zn at pH 6 and 8 and spiked with Zn treatments (nano and ionic). We found that treating seeds with bare ZnO NPs significantly enhanced grain Zn concentrations as compared to the control, DEX-ZnO NPs, and ZnSO4. There were no differences in grain Zn concentration of plants treated with ionic or nano Zn treatments regardless of the soil pH. This work has elucidated important principles which will help carry forward efforts at developing effective ZnO NP-based fertilizers. It also suggests that treatment of seeds with ZnO NPs is more effective than amending soil or treating seeds with ZnSO4.
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Sil, Devika. "SYNTHESIS AND APPLICATIONS OF PLASMONIC NANOSTRUCTURES." Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/364016.
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ChemistryPh.D.
The localized surface plasmon resonance (LSPR), arising due to the collective oscillation of free electrons in metal nanoparticles, is a sensitive probe of the nanostructure and its surrounding dielectric medium. Synthetic strategies for developing surfactant free nanoparticles using ultrafast lasers providing direct access to the metallic surface that harvest the localized surface plasmons will be discussed first followed by the applications. It is well known that the hot carriers generated as a result of plasmonic excitation can participate and catalyze chemical reactions. One such reaction is the dissociation of hydrogen. By the virtue of plasmonic excitation, an inert metal like Au can become reactive enough to support the dissociation of hydrogen at room temperature, thereby making it possible to optically detect this explosive gas. The mechanism of sensing is still not well understood. However, a hypothesis is that the dissociation of hydrogen may lead to the formation of a metastable gold hydride with optical properties distinct from the initial Au nanostructures, causing a reversible increase in transmission and blue shift in LSPR. It will also be shown that by tracking the LSPR of bare Au nanoparticles grown on a substrate, the adsorption of halide ions on Au can be detected exclusively. The shift in LSPR frequency is attributed to changes in electron density rather than the morphology of the nanostructures, which is often the case.
Temple University--Theses
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Aygar, Gulfem. "Preparation Of Silica Coated Cobalt Ferrite Magnetic Nanoparticles For The Purification Of Histidine-tagged Proteins." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613894/index.pdf.
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The magnetic separation approach has several advantages compared with conventional separation methodsit can be performed directly in crude samples containing suspended solid materials without pretreatment, and can easily isolate some biomolecules from aqueous systems in the presence of magnetic gradient fields. This thesis focused on the development of new class of magnetic separation material particularly useful for the separation of histidine-tagged proteins from the complex matrixes through the use of imidazole side chains of histidine molecules. For that reason surface modified cobalt ferrite nanoparticles which contain Ni-NTA affinity group were synthesized. Firstly, cobalt ferrite nanoparticles with a narrow size distribution were prepared in aqueous solution using the controlled coprecipitation method. In order to obtain small size of agglomerates two different dispersants, oleic acid and sodium chloride, were tried. After obtaining the best dispersant and optimum experimental conditions, ultrasonic bath was used in order to decrease the size of agglomerates. Then, they were coated with silica and this was followed by surface modification of these nanoparticles by amine in order to add functional groups on silica shell. Next, &ndash
COOH functional groups were added to silica coated cobalt ferrite magnetic nanoparticles through the NH2 groups. After that N&alpha
,N&alpha
-Bis(carboxymethyl)-L-lysine hydrate, NTA, was attached to carboxyl side of the structure. Finally, nanoparticles were labeled with Ni (II) ions. The size of the magnetic nanoparticles and their agglomerates were determined by FE-SEM images, particle size analyzer, and zeta potential analyzer (zeta-sizer). Vibrational sample magnetometer (VSM) was used to measure the magnetic behavior of cobalt ferrite and silica coated cobalt ferrite magnetic nanoparticles. Surface modifications of magnetic nanoparticles were followed by FT-IR measurements. ICP-OES was used to find the amount of Ni (II) ion concentration that was attached to the magnetic nanoparticle.
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Beyerlein, Kenneth Roy. "Simulation and modeling of the powder diffraction pattern from nanoparticles: studying the influence of surface strain." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41211.
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Accurate statistical characterization of nanomaterials is crucial for their use in emerging technologies. This work investigates how different structural characteristics of metal nanoparticles influence the line profiles of the corresponding powder diffraction pattern. The effects of crystallite size, shape, lattice dynamics, and surface strain are all systematically studied in terms of their impact on the line profiles.
The studied patterns are simulated from atomistic models of nanoparticles via the Debye function. This approach allows for the existing theories of diffraction to be tested, and extended, in an effort to improve the characterization of small crystallites. It also begins to allow for the incorporation of atomistic simulations into the field of diffraction. Molecular dynamics simulations are shown to be effective in generating realistic structural models and dynamics of an atomic system, and are then used to study the observed features in the powder diffraction pattern.
Furthermore, the characterization of a sample of shape controlled Pt nanoparticles is carried out through the use of a developed Debye function analysis routine in an effort to determine the predominant particle shape. The results of this modeling are shown to be in good agreement with complementary characterization methods, like transmission electron microscopy and cyclic voltammetry.
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Tait, Steven L. "Desorption kinetics of small n-alkanes from MgO(100), Pt(111), and C(0001)/Pt(111) and studies of Pd nanoparticles : growth and sintering on Al₂O₃(0001) and methane dissociation on MgO(100) /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9630.
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Zin, Melvin T. "Self-assembly and nanofabrication approaches towards photonics and plasmonics /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/15502.
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Dorney, Kevin Michael. "A Chemical Free Approach for Increasing the Biochemical Surface-Enhanced Raman Spectroscopy (SERS)-Based Sensing Capabilities of Colloidal Silver Nanoparticles." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401206511.
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