[PDF] Molecular Engineering Of Gold Nanorod Surfaces Towards Improved Physical Properties And Understanding Nanoparticle Cell Interactions eBook

Author : Alaaldin M. Alkilany
Publisher :
Page : pages
File Size : 38,52 MB
Release : 2011
Category :
ISBN :

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Gold nanorods have unique optical properties and various promising applications. Wet chemical synthesis of gold nanorods requires the use of cetyl trimethylammonium bromide (CTAB) as shape-directing surfactant, which form a bilayer on the surfaces of gold nanorods. CTAB bilayer stabilizes the nanorods against aggregation and has the ability to sequester organic molecules from aqueous bulk. CTAB molecules in the bilayer are held via weak hydrophobic forces and thus tend to desorb resulting in nanorods aggregation and toxicity to cultured cells. Herein, three surface-engineering approaches to enhance the colloidal physical stability and biocompatibility of gold nanorods have been examined: 1) electrostatic approach via overcoating with polyelectrolytes; 2) covalent approach via surfactant polymerization; 3) and hydrophobic approach via cholesterol insertion into the bilayer. Layer-by-layer coating has been used to overcoat CTAB-capped nanorods with both negatively and positively charged polyelectrolytes. Compared to CTAB-capped nanorods, polyelectrolyte-coated gold nanorods showed improved stability against aggregation in culture medium and enhanced biocompatibility to cultured cells. The toxicity of CTAB-capped gold nanorod solutions was assigned quantitatively to free CTAB molecules, where gold nanorods themselves were found not toxic. Similar biocompatibility profiles for both cationic and anionic coated-gold nanorods were observed due to spontaneous protein adsorption. In growth media, all examined nanorods were covered with protein corona and thus bear similar negative effective surface charge explaining their similar toxicity profiles. ! """! ! Our covalent approach to stabilize the surfactant bilayer on the surface of gold nanorods relies on synthesizing a polymerizable version of the CTAB, which we have used to prepare gold nanoparticles (both spheres and rods). Surfactant polymerization on the surface of gold nanoparticles was found to retard surfactant desorption and thus enhance both stability against aggregation and biocombatibility of these nanomaterials. The hydrophobic approach to stabilize the CTAB bilayer on gold nanorods relies on using a bilayer-condensing agent such as cholesterol to increase the total hydrophobic interactions. Cholesterol is known to consist of up to 50% of mammalian cell membrane0́9s total lipids, and thus have important effect on their stability and physical properties. Using cholesterol-rich growth medium, we have prepared gold nanorods with excellent size and shape distribution. The prepared gold nanorods in the presence of cholesterol have a significantly higher surface charge and exhibit superior stability against aggregation compared to the nanorods prepared without cholesterol. In addition to the enhanced aqueous stability and biocompatibility, stabilization the CTAB bilayer on the surface of gold nanorods have allowed for suspension gold nanorods in organic solvents without aggregation. Polyelectrolyte-coated gold nanorods showed remarkable stability in polar organic solvents against aggregation as compared to CTAB-capped nanorods. The suspendability of coated-gold nanorods in polar organic solvents facilitates the incorporation of these nanomaterials into hydrophobic polymers and thus fabrication of thin films that contain uniform gold nanorod dispersions (nanocomposites).

Author : Valerio Voliani
Publisher : Smithers Rapra
Page : 156 pages
File Size : 22,92 MB
Release : 2013-01-29
Category : Medical
ISBN : 1847356443

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In the last decade, gold nanoparticles have provided a suitable platform for the development of novel and efficient diagnostic and therapeutic tools, which avoid the typical drawbacks of the old systems. They are biocompatible and they can be easily synthesised, encapsulated and functionalised with (bio)molecules. Nanoparticles produced by a wet chemistry synthesis have the geometry, which enables the complete control of their optical and physical properties. It is also possible to influence the targeting and stability/release behaviour by coating the nanoparticle surface. In this Update the reader can find in a single volume the methods used most often for the synthesis and coating of gold nanoparticles (spheres, cages, cubes, rods), the links between optical features and geometries of gold nanoparticles, and the novel applications in nanomedicine of gold nanoparticles determined by their geometry. One of the main objectives of this Update is to provide, a readily comprehensible connection in all the chapters between the geometry of gold nanoparticles and their final applications. Another target of this book is to provide information about efficient processes for the synthesis and the coating of gold nanoparticles, all of which have been directly tested by the author. This Update offers comprehensive information on the whole topic from the synthesis of the gold nanoparticles to their medical applications; this is accompanied by a complete and recent bibliography, in order to give to the readers the opportunity to research further the topics addressed in the book. In this way, students and researchers from academia and industry can have a complete picture of gold nanostructures, physicians and biologists can develop ideas and applications for the new nano-tools, and chemists can have a general guide to the synthesis of gold nanoparticles. This is a state-of-the-art guide for the synthesis and uses of gold nanoparticles.

Author : Valerio Voliani
Publisher : Walter de Gruyter GmbH & Co KG
Page : 113 pages
File Size : 21,87 MB
Release : 2020-04-20
Category : Medical
ISBN : 1501511459

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Gold nanoparticles provide a platform for the development of new and efficient diagnostic and therapeutic tools.This book offers a general guide to the synthesis and coating of gold nanoparticles. It describes the links between optical features and geometries of gold nanoparticles and provides a readily comprehensible connection in all the chapters between the geometry of gold nanoparticles and their final applications.

Author : Catherine Louis
Publisher : World Scientific
Page : 681 pages
File Size : 14,14 MB
Release : 2017-06-02
Category : Science
ISBN : 1786341263

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Gold Nanoparticles for Physics, Chemistry and Biology offers an overview of recent research into gold nanoparticles, covering their discovery, usage and contemporary practical applications.This Second Edition begins with a history of over 2000 years of the use of gold nanoparticles, with a review of the specific properties which make gold unique. Updated chapters include gold nanoparticle preparation methods, their plasmon resonance and thermo-optical properties, their catalytic properties and their future technological applications. New chapters have been included, and reveal the growing impact of plasmonics in research, with an introduction to quantum plasmonics, plasmon assisted catalysis and electro-photon conversion. The growing field of nanoparticles for health is also addressed with a study of gold nanoparticles as radiosensibiliser for radiotherapy, and of gold nanoparticle functionalisation. This new edition also considers the relevance of bimetallic nanoparticles for specific applications.World-class scientists provide the most up-to-date findings for an introduction to gold nanoparticles within the related areas of chemistry, biology, material science, optics and physics. It is perfectly suited to advanced level students and researchers looking to enhance their knowledge in the study of gold nanoparticles.

Author : Idah C. Pekcevik
Publisher :
Page : 194 pages
File Size : 27,5 MB
Release : 2014
Category :
ISBN :

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The surface chemistry of nanoparticles imparts colloidal stability to nanoparticles by acting as barriers between their surrounding environment and the nanoparticles. Gold nanoparticles (AuNPs) are an ideal platform for many studies because of localized surface plasmon resonant properties, chemical stability, and the relative ease of modifying their surfaces with a wide variety of molecular coatings (e.g., alkanethiolates). Understanding and improving the physicochemical stability of these surface-modified nanoparticles is essential for their reproducible use in each application. The long-term colloidal stability of AuNPs relies on the resistance of their surface modifications to thermal degradation, chemical attack and oxidizing conditions. For this purpose, my research has been focused on determining the quality of molecular coatings on gold nanoparticles, and developing techniques, which are complementary to each other, to assess the quality factor of these coatings. Gold nanoparticles with varied qualities of molecular coatings were prepared and tested for their relative stabilities under various physical (e.g., temperature, time, laser irradiation) and chemical (e.g., in presence of metal etchants) conditions. We found that the quality of molecular coatings on AuNPs depends on the process conditions such as solution composition (e.g., the presence of co-surfactants, concentration of excess surfactants), density of capping molecules, and process time, used to form these coatings. We found that higher quality molecular coatings on the gold colloids increased the chances that the particles would remain stable over the over the duration of their intended use. Those colloids modified with relatively higher quality self-assembled monolayers were also more resistant to cyanide etching. These results highlight the importance of methodology for preparing high quality monolayers on nanoparticles and testing their ability to remain stable over the duration of their intended use, for example, during photothermal processes. In addition, the loading of DNA molecules onto AuNPs was tuned to achieve varying densities of DNA, and through this work, achieved the highest reported loading of single-stranded DNA (ss-DNA) molecules on gold nanorods. These high loadings of DNA oligonucleotides could enable a high loading of therapeutics onto the nanorods, which could translate into a higher or more prolonged delivery of therapeutic doses when actived by photothermal or other processes.

Author : Klaus Wandelt
Publisher : Wiley-VCH
Page : 500 pages
File Size : 36,49 MB
Release : 2020-01-10
Category :
ISBN : 9783527680597

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Covering interface science from a novel surface science perspective, this seven-volume handbook offers a comprehensive overview of both these and numerous other topics. The initial chapters treat basic fundamentals on such topics as vacuum technology, while general chapters -- where appropriate -- describe theoretical methods and provide models to help explain the respective phenomena, such as band structure calculations, chemisorption and segregation. Additionally, short references to more specialized methodology accompany the descriptions of the most important techniques. Ideal as a reference for scientists in the field, as well as an introduction to current methods for newcomers.

Author : Patrick N. Sisco
Publisher :
Page : pages
File Size : 36,47 MB
Release : 2011
Category :
ISBN :

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Gold nanoparticles have attracted great interest in the last decade for applications in biochemical detection, imaging, and therapeutics, due to their useful optoelectronic properties. Interest in this area has recently focused on engineering the surface of the nanoparticles, because of the ease in which the charge, functionality, and reactivity of the surface can be altered. This dissertation will focus on the applications of surface-engineered gold nanoparticles in chemical detection and biomedical imaging, and look at the effects surface modified gold nanorods have on the behavior of cardiac fibroblasts in tissue culture. As an alternative to solution-based techniques in Raman spectroscopy, we have found that a sandwich architecture in which a surface assembled monolayer (SAM) of 4-mercaptobenzoic acid (4-MBA) is sandwiched between a 100 nm thick gold substrate and electrostaticaly immobilized gold nanocubes allows for more reproducible data as well as enhancement factors up to 1013. The sandwich architecture creates a large electromagnetic field in the area where the 4-MBA molecules reside causing the characteristic vibrational modes of 4-MBA to appear. We have also moved out of the realm of chemical sensing and have used our gold nanorods as point sensors to monitor the mechanical properties associated with mechanotransduction. Cell behavior in the presence of nanomaterials is typically explored through simple viability assays, but there is mounting evidence that nanomaterials can have more subtle effects on a variety of cell functions. Numerous studies have documented the cellular uptake and cytotoxicity of gold nanoparticles in different cell types, but very little is known about how nanoparticles affect cellular function. We have shown that gold nanorods in a collagen thin film can be used to measure the local mechanical fields near and between living cells as they assess, adapt, and rearrange their environment. We have also found that gold nanorods in 3-D tissue culture interfere with the cardiac fibroblast-mediated remodeling of a collagen tissue construct. We have found several factors associated with the dose dependent decrease in cell-mediated collagen remodeling including the alteration of fibroblast phenotype, adsorption of cellular proteins needed for cell mediated remodeling, as well as a change in the mechanical properties of the tissue construct. The following chapters will detail the use of our gold nanomaterials as both biochemical and imaging agents, and discuss cell behavior in the presence of surface modified gold nanorods.

Author : Pedro H.C. Camargo
Publisher : John Wiley & Sons
Page : 354 pages
File Size : 21,95 MB
Release : 2021-06-21
Category : Technology & Engineering
ISBN : 352734750X

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Explore this comprehensive discussion of the foundational and advanced topics in plasmonic catalysis from two leaders in the field Plasmonic Catalysis: From Fundamentals to Applications delivers a thorough treatment of plasmonic catalysis, from its theoretical foundations to myriad applications in industry and academia. In addition to the fundamentals, the book covers the theory, properties, synthesis, and various reaction types of plasmonic catalysis. It also covers its applications in reactions including oxidation, reduction, nitrogen fixation, CO2 reduction, and more. The book characterizes plasmonic catalytic systems and describes their properties, tackling the integration of conventional methods as well as new methods able to unravel the optical, electronic, and chemical properties of these systems. It also describes the fundamentals of controlled synthesis of metal nanoparticles relevant to plasmonic catalysis, as well as practical examples thereof. Plasmonic Catalysis covers a wide variety of other practical topics in the field, including hydrogenation reactions and the harvesting of LSPR-excited charge carriers. Readers will also benefit from the inclusion of: A thorough introduction to plasmonic catalysis, a theory of plasmons for catalysis and mechanisms, as well as optical properties of plasmonic-catalytic nanostructures An exploration of the synthesis of plasmonic nanoparticles for photo and electro catalysis, as well as plasmonic catalysis towards oxidation reactions and hydrogenation reactions Discussions of plasmonic catalysis for multi-electron processes and artificial photosynthesis and N2 fixation An examination of control over reaction selectivity in plasmonic catalysis Perfect for catalytic chemists, materials scientists, photochemists, and physical chemists, Plasmonic Catalysis: From Fundamentals to Applications will also earn a place in the libraries of physicists who seek a one-stop resource to enhance their understanding of applications in plasmonic catalysis.

Author : R. Navanietha Krishnaraj
Publisher : John Wiley & Sons
Page : 420 pages
File Size : 11,1 MB
Release : 2021-11-02
Category : Technology & Engineering
ISBN : 1119617197

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MICROBIAL INTERACTIONS AT NANOBIOTECHNOLOGY INTERFACES This book covers a wide range of topics including synthesis of nanomaterials with specific size, shape, and properties, structure-function relationships, tailoring the surface of nanomaterials for improving the properties, interaction of nanomaterials with proteins/microorganism/eukaryotic cells, and applications in different sectors. This book also provides a strong foundation for researchers who are interested to venture into developing functionalized nanomaterials for any biological applications in their research. Practical concepts such as modelling nanomaterials, and simulating the molecular interactions with biomolecules, transcriptomic or genomic approaches, advanced imaging techniques to investigate the functionalization of nanomaterials/interaction of nanomaterials with biomolecules and microorganisms are some of the chapters that offer significant benefits to the researchers.