Synthesis and Characterization of Core-shell Nanoparticles, and a Study of Their Use as Encapsulation Agents PDF Download

Author: Jorge L. Chávez Benavides
Publisher:
ISBN:
Category :
Languages : en
Pages :

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These studies suggested that the sequestered probes could interact with each other producing a dynamic quenching of the donor. Finally, we covalently attached another hydrophobic fluorescent probe to the particles to study the level of interaction with the solvent, observing that the probe preferred to react in the interior pores of the particles to reduce interaction with the polar media.

Author: Kyler James Carroll
Publisher:
ISBN:
Category : Biosensors
Languages : en
Pages :

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The design of core/shell nanoparticles is of great interest for a wide range of applications. The primary focus of this dissertation is on the design and optimization of two synthetic routes. The first one is an aqueous reduction method using sodium borohydride and sodium citrate. This method was extended to design two types of core/shell nanoparticles, both of which have many applications in bio-sensing, magnetic resonance imaging, and magnetically guided SERS for the identification of environmental threats. The first, Fe/Ag core/shell nanoparticles were designed using a novel one-pot method by varying the AgNO3 addition time in the system. For example, if AgNO3 is added five minutes after the start of the reaction, the already formed Fe nanoparticles serve as seeds for heterogeneous nucleation and growth of Ag nanoparticles. The result of the synthesis was 50 nanometer spherical particles with a narrow size distribution. The second type, Fe/SiO2/Au core/shell nanoparticles were designed using a two-step method. First, 150 nanometer spherical Fe nanoparticles were synthesized followed by the addition of tetraethylorthosilicate (TEOS). This created a Fe/SiO2 core/shell nanoparticle to which HAuCl3 was added. In both cases, Fe/Ag and Fe/SiO2/Au, the formed nanoparticles were characterized and tested for the application as SERS active materials. The second part of this dissertation work was focused on using the polyol method to design bimetallic Cu/Ni, Fe/FeOx, and Co/C core/shell nanoparticles. In each case, the polyol method provided an easy one-pot reaction to synthesize these novel nanomaterials. The design of the Cu/Ni nanoparticles allowed for further insight into the polyol mechanism by independently investigating the factors that govern the formation of elemental Cu and Ni nanoparticles. By understanding the ability of the polyols to easily prepare metal and metal oxide nanoparticles, we were able to manipulate a one-pot reaction to design an aqueous ferrofluid consisting of Fe/FeOx nanoparticles. These spherical 15 nanometer particles were studied for their potential application as MRI contrast agents. In addition, the aqueous ferrofluid served as a precursor for the design of magnetic/luminescent core/shell nanoparticles. Finally, the polyol method was extended to create Co/C nanoparticles for permanent magnet applications.

Author: Ryan Evan Schwarb
Publisher:
ISBN:
Category : Fuel
Languages : en
Pages : 80

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Recent advances in the science of nanoparticle synthesis have resulted in new core-shell nanoparticles displaying novel, unique, and potentially valuable properties for their use in propellants, fuels, and explosives. This research was conducted in support of the Propulsion Directorate of the Air Force Research Laboratory aimed at the development of functional reactive nanoparticles as fuel additives for improved thermal stability. In this work, oxidation of highly reactive zero-valent iron nanoparticles coated to prevent agglomeration and early reaction was studied as a novel approach to remove oxygen from the fuels. The particles were synthesized using sonochemistry, a well-established technique to self assemble core-shell nanoparticles, where the solution of pentacarbonyl Fe(CO)5 in dodecane was sonciated in the presence of an encapsulating compound, or shell material, to produce core-shell nanoparticles (CSNPs). The nanoparticles were stable at the temperatures below 120°C; at elevated temperatures, the shell material allows oxygen to permeate and react with the iron core depleting the oxygen from solution. It was observed that altering the structure of the shell material significantly influences the temperature-controlled oxidation of CSNPs over a range from 130°C to 188°C. This thesis investigates various shell material parameters including chain length, structural perturbation, and functional group to protect the iron core from oxidation at low temperatures and enable temperature-controlled oxidation of the iron core at higher temperatures. The impact of shell material parameters on CSNP solubility, particle diameter and temperature-controlled oxidation are investigated and reported.

Author: Kamel A. Abd-Elsalam
Publisher: Elsevier
ISBN: 0128245093
Category : Technology & Engineering
Languages : en
Pages : 798

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Green Synthesis of Silver Nanomaterials illustrates how to biologically scale up silver nanoparticle synthesis. This book covers green synthesis of silver nanomaterials, via plants, agricultural waste, fungi, and microorganisms. Sections cover the synthesis and characterization of chemical and green synthesis, various types of silver nanomaterialism, the ability of different fungal species, such as filamentous fungi, to produce silver nanoparticles, the microbial synthesis of silver NMs, biosynthesis mechanisms, toxicity, fate and commercialization. As examples, greener pathways and mechanisms, toxicity of silver nanoparticles in aquatic life and in natural eco-systems, and strategies for the scaling up of green-synthesized nanomaterials are discussed. With the extended work in enhancing nanomaterials synthesis performance, and discovering their biomedical, environmental, and agricultural applications, it is hoped that the execution of these methods on a large scale and their industrial applications in different fields will take place in the near future. - Assesses the impact of a large variety of silver-based nanostructures in the biomedical, environmental and agri-food sectors - Discusses the major synthesis methods used for effectively processing plant-based silver nanoparticles - Outlines the potential and major challenges for adopting green synthesis methods on a mass scale

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 810

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Author: Avin Yan
Publisher:
ISBN:
Category : Education
Languages : en
Pages : 0

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"Metal Oxide Core-Shell Nanoparticle Synthesis and Applications" is an essential guide for researchers and scientists working in the field of materials science, particularly in the area of nanotechnology. Author is a distinguished expert in the field, this book provides a comprehensive overview of the synthesis and applications of metal oxide core-shell nanoparticles. The book begins with an introduction to the fundamental concepts of nanotechnology and the synthesis of metal oxide nanoparticles, followed by a detailed discussion of the core-shell structure and the different synthesis methods used to produce these particles. The author also covers the characterization techniques used to analyze the properties of these particles, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The latter half of the book is dedicated to exploring the various applications of metal oxide core-shell nanoparticles, including their use in catalysis, energy storage, environmental remediation, and biomedical applications. The author provides examples of current research in these areas and discusses the potential future directions for research in this field. Overall, "Metal Oxide Core-Shell Nanoparticle Synthesis and Applications" is a valuable resource for scientists and researchers seeking to advance their understanding of the synthesis and application of metal oxide core-shell nanoparticles. The clear and concise writing style, combined with the extensive references and practical examples, makes this book an essential addition to any materials science library.

Author: Jonathan G. McGrath
Publisher:
ISBN:
Category :
Languages : en
Pages : 236

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This dissertation describes the use of spherical core/shell type micro- and nanoparticles as building blocks for the fabrication of colloidal crystals. The polymer component used in all of the projects that are described herein is poly-N-isopropylacrylamide (pNIPAm). The polymeric identity of particles composed of this soft, hydrogel material, which is also thermoresponsive, contributes to the self-assembly of such particles to form ordered structures. Chapter 2 examines a characterization technique using fluorescence resonance energy transfer (FRET) to investigate the structure of particles that possess a core/shell topology. Chapters 4-6 investigate strategies to impart both hard (dense core) and soft (flexible shell) properties to the particles by using styrene as the main component in a copolymer synthesis with pNIPAm (pS- co-NIPAm particles). The resulting crystal assemblies, which could be formed by simple drying procedures, were demonstrated to be robust and their application as processable, photonic inks is also investigated. Chapter 7 examines the ability to crosslink these crystals together by simple heating methods to produce robust films, and the optical properties of these crystal films could be tuned by simple rehydration. Chapters 3 and 5 examine the synthesis and self-assembly strategies of core/shell particles using the properties of pNIPAm shell layers that have been added to different types of core particles (silver or pS-co-NIPAm) for the purposes of fabricating colloidal crystals using thermal annealing procedures. Chapter 8 explores the use of silver particles as tracers for the characterization of colloidal crystals composed of thermally annealed colloidal crystals composed of pNIPAm hydrogel particles.

Author: Wolfram Hergert
Publisher: Springer
ISBN: 3642287387
Category : Science
Languages : en
Pages : 268

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This book presents in a concise way the Mie theory and its current applications. It begins with an overview of current theories, computational methods, experimental techniques, and applications of optics of small particles. There is also some biographic information on Gustav Mie, who published his famous paper on the colour of Gold colloids in 1908. The Mie solution for the light scattering of small spherical particles set the basis for more advanced scattering theories and today there are many methods to calculate light scattering and absorption for practically any shape and composition of particles. The optics of small particles is of interest in industrial, atmospheric, astronomic and other research. The book covers the latest developments in divers fields in scattering theory such as plasmon resonance, multiple scattering and optical force.

Author: Sriya Sanyal
Publisher:
ISBN:
Category : Composite materials
Languages : en
Pages : 186

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Nanoparticles are ubiquitous in various fields due to their unique properties not seen in similar bulk materials. Among them, core-shell composite nanoparticles are an important class of materials which are attractive for their applications in catalysis, sensing, electromagnetic shielding, drug delivery, and environmental remediation. This dissertation focuses on the study of core-shell type of nanoparticles where a polymer serves as the core and inorganic nanoparticles are the shell. This is an interesting class of supramolecular building blocks and can "exhibit unusual, possibly unique, properties which cannot be obtained simply by co-mixing polymer and inorganic particles". The one-step Pickering emulsion polymerization method was successfully developed and applied to synthesize polystyrene-silica core-shell composite particles. Possible mechanisms of the Pickering emulsion polymerization were also explored. The silica nanoparticles were thermodynamically favorable to self-assemble at liquid-liquid interfaces at the initial stage of polymerization and remained at the interface to finally form the shells of the composite particles. More importantly, Pickering emulsion polymerization was employed to synthesize polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles with N-isopropylacrylamide incorporated into the core as a co-monomer. The composite nanoparticles were temperature sensitive and could be up-taken by human prostate cancer cells and demonstrated effectiveness in drug delivery and cancer therapy. Similarly, by incorporating poly-2-(N, N)-dimethylamino)ethyl methacrylate (PDMA) into the core, pH sensitive core-shell composite nanoparticles were synthesized and applied as effective carriers to release a rheological modifier upon a pH change. Finally, the research focuses on facile approaches to engineer the transition of the temperature-sensitive particles and develop composite core-shell nanoparticles with a metallic shell.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 219

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The concept of nanotechnology is attributed to Nobel prize winner Richard Feynman who gave a very famous, visionary in 1959 (published in 1960) during one of his lectures, saying: "the principles of physic, as far as I can see, do not speak against the possibility of maneuvering things atom by atom". At the time, Feynman's words were received as pure science fiction". Today, we have instruments that allow precisely what Feynman had predicted: creating structures by moving atoms individually. In principle, the ultimate results of this research study leads to the synthesis of magnetic and porous carbon based nanoparticles as the material and tool for biomedical applications. Currently, we are in a battle with a dangerous and destructive diseases such as cancers, and nanotechnology is then presented as a tool that can help us win control. This work is to support medical and other applications of nanotechnology specifically aimed to prepare carbon based nanoparticles. Magnetic nanoparticles are being of great interest because of their unique properties especially in drug delivery, hyperthermia, magnetic resonance imaging and cell separation. In many clinical situations, medication doses are oversized as a result of impaired drug absorption or tissue unspecific delivery. The ultimate goal of magnetically controlled drug delivery and drug therapy is to selectively delivering drug molecules to the diseased site without a concurrent increase in its level in healthy tissues. Consequently, in this research study the objective is to develop an approach to control the synthesis of carbon encapsulated iron nanoparticles in the form of core@shell nanostructure. Accordingly, understanding and revealing the growth mechanism of carbon encapsulated iron nanoparticles is necessary by doing characterization. Furthermore, engineering of suitable carbon based nanoparticles for biomedical applications has been also considered. Common challenges for synthesis of carbon encapsulated iron nanoparticles are improving uniformity, enhancing coating protection and controlling particles compositions, shape and core/shell sizes. In addition, due to the lack of comprehensive understanding of the optimal parameters and formation mechanism most of the current fabrication process are empirical, which means a large number of experimental trials are required to optimize any given process. Since the last two decades, arc discharge technique leads to the discovery of two important carbon based materials, nanotubes and fullerenes. However, the formation of nanomaterials by thermal plasma still remains poorly understood and need further investigation. The focus in this study is on synthesis of carbon based nanoparticles by arc discharge method, particularly carbon encapsulated iron nanoparticles in the form of Core@Shell nanostructure. An arc discharge reactor that was patented by FEMAN group was used with slight modification. The growth processes were elucidated through many experiments and characterizations. Precise control over carbon encapsulated iron nanoparticles were addressed. In addition, a new carbon encapsulated multi iron nanoparticles is introduced. The results have been lead to new elements for understanding the growth mechanism of iron core and carbon shell nanostructure. In order to improve the synthesis process, a new modified arc discharge reactor was developed and implemented. Two new materials are prepared through a new facile synthetic method; carbon nanoparticles decorated by fullerenes and spherical porous carbon microparticles. Last but not least, in this research medical application requirements have been taken into account to prepare suitable nanoparticle.