© Springer Science+Business Media Dordrecht 2016 / Reducing AgNO3 by glucose at basic pH coated the surface of silica spheres with a high density of hemispherical silver nanoparticles (average diameter 3.2±1 nm). A much lower silver concentration than is standard favored heterogeneous nucleation of silver on the silica surface at the expense of homogeneous nucleation in solution. The slow growth rate of the nuclei promoted the formation of discrete silver particles rather than a continuous shell. Based on scanning electron microscopy and transmission electron microscopy, the surface coverage of silver seed particles was as high as 25% at 10 °C without prior functionalization of the silica. The particles were composed of metallic silver based on x-ray photoelectron spectroscopy. There was a sharp increase in the silver surface coverage and decrease in the particle size when the temperature was raised from 5 °C to 10 °C and the amount of silica was decreased from 0.2 to 0.025 V/V. The size was controlled by the diffusion barrier through the ion shell surrounding the silica spheres and by maintaining reaction conditions where the particles on the surface compete for silver.

Metal nanoparticles have received much interest for their application in catalysis due to high surface-to-volume ratios resulting in more available active sites. Ideally these catalysts are heterogeneous and allow for facile separation from the catalytic reaction mixture making them ideal for industrial application. Dispersed metal nanoparticles are explored due to their high reactivity in solution and are stabilized by surfactants and polymers. However, it is difficult to determine whether or not a catalyst is truly heterogeneous as a certain degree of leaching from the metal nanoparticle is inevitable. Determining the mechanisms involved in nanocatalysis is also a challenge. In this study, a series of dispersed palladium nanocatalysts in the Suzuki reaction with phenylboronic acid and bromobenzene were characterized before and after catalysis to determine what changes occur. Samples where characterized before and after the catalytic reaction by XPS, SEM, and EDS to monitor changes in particle size and composition. Reaction mixtures after catalysis were analyzed by ICP-MS for leached palladium species to determine if concentrations were high enough for homogeneous catalysis to take place. The dispersed palladium nanoparticles studied experienced growth during the catalytic process and a significant amount of leaching. XPS analysis indicates the presence of aromatic species on the particle surface after the catalytic reaction. The aromatic species is likely biphenyl, the product of the catalytic reaction, as the presence of boron and bromine was not found in XPS and EDS analysis.

Nanotechnology has recently emerged as a strong contributor toward research efforts to develop targeted systems of drug delivery in cancer therapy. Our work investigates the therapeutic potential of Targeted Charge-Reversal Nanoparticles (TCRNs), a novel nanoparticle with in vitro evidence of nuclear drug delivery. Using M12 prostate cancer cells, MDA-MB-231 breast cancer cells, and modified derivatives of these cell lines, we investigated the ability of Folic Acid-tagged TCRNs to deliver Nile Red and Dimethyl Indole Redfluorescent (DiR) fluorescent dyes to the nucleus of cells using confocal microscopy and in vivo biphontonic imaging using Xenogen® Technology. Confocal imaging with the SCP28 derivative of MDA-MB-231 cells shows nuclear association of the TCRNs over time, although specific nuclear deposition was unclear. Biophotonic imaging with M12 and SCP28 xenograft tumors in athymic nude mice shows retention of TCRNs in animals out to 7 days with minimal localization of TCRNs to tumor tissues. Our findings suggest that further characterization and manipulation of both the cells and the nanoparticle is necessary in order to make definitive claims regarding the TCRN’s ability to deliver fluorescent dyes, and eventually therapeutic compounds, to the nucleus of cells.

The development of hybrid PET/MRI imaging systems needs to be paralleled with the development of a hybrid intrinsic PET/MRI probes. The aim of this work was to develop and validate a novel radio-superparamagnetic nanoparticle (r-SPNP) for hybrid PET/MRI imaging. This was achieved with the synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) that intrinsically incorporated 59Fe and manganese iron oxide nanoparticles (MIONs) that intrinsically incorporated 52Mn. Both [59Fe]-SPIONs and [52Mn]-MIONs were produced through thermal decomposition synthesis. The physiochemical characteristics of the r-SPNPs were assessed with TEM, DLS, and zeta-potential measurements, as well as in imaging phantom studies. The [59Fe]-SPIONs were evaluated in vivo with biodistribution and MR imaging studies. The biodistrubution studies of [59Fe]-SPIONs showed uptake in the liver. This corresponded with major MR signal contrast measured in the liver. 52Mn was produced on natural chromium through the 52Cr(p,n)52Mn reaction. The manganese radionuclides were separated from the target material through a liquid-liquid extraction. The αVβ3 integrin binding of [52Mn]-MION-cRGDs was evaluated with αVβ3 integrin solid phase assays, and the expression of αVβ3 integrin in U87MG xenograft tumors was characterized with fluorescence flow cytometry. [52Mn]-MION-cRGDs were used for in vivo PET and MR imaging of U87MG xenograft tumor bearing mice. PET data showed increased [52Mn]-MION-cRGD uptake compared with untargeted [52Mn]-MIONs. ROI analysis of PET and MRI data showed that MR contrasted corresponded with PET signal. Future work will utilize [52Mn]-MION-cRGDs in other tumor models and with hybrid PET/MRI imaging systems.

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.

Dans le contexte du développement exponentiel des nanotechnologies, les nanomatériaux sont susceptibles de se disséminer dans l'environnement. Les végétaux sont un élément sensible des écosystèmes car ils constituent une interface entre l'eau, le sol et l'air et se situent à la base de la chaine trophique. Cette étude avait pour but d'évaluer l'impact des nanoparticules de TiO2 et des nanotubes de carbone sur les végétaux, et plus particulièrement sur le blé et le colza. L'accent a également était mis sur la caractérisation des nanomatériaux employés. Nous avons mis en évidence l'accumulation racinaire et le transfert vers les feuilles des nanoparticules de TiO2 et des NTC dans le blé et le colza après une exposition en hydroponie. Les nanoparticules de TiO2 sont également accumulées dans les plantes lors d'une exposition racinaire sur sol ou encore lors d'une exposition par voie aérienne. Les nanoparticules de TiO2 s'accumulent dans les végétaux à hauteur de quelques dizaines voire centaines de mg Ti/kg MS, leur phase cristalline n'est pas modifiée et ces nanoparticules ne se dissolvent pas lors de leur transfert dans le végétal. Les NTC s'accumulent en plus faible quantité (centaines de µg NTC/kg MS) et il semble qu'ils soient altérés par le contact avec le végétal. Ces nanomatériaux affectent peu le développement des végétaux. Sur huit tests réalisés, seule l'élongation racinaire s'est révélée être un critère sensible, avec une induction de l'élongation pour les NPs et les NTC présentant le plus faible diamètre nominal. Enfin, une nette influence du diamètre nominal des nanomatériaux a pu être mise en évidence, contrôlant ainsi leur internalisation, leur transfert et leurs effets biologiques sur les végétaux. / The field of the nanotechnology exponentially increased during the last ten years. Intensive production of nanomaterials would lead to their release in the environment. Plants are one of the most sensitive organisms since they are at the interface between soil, water and air. Moreover, they represent a point of entry into the food chain. This study deals with the impact of TiO2 nanoparticle and carbon nanotube on plants, specifically on wheat and rapeseed. The physico-chemistry of nanomaterials has been deeply characterized.We prove that TiO2 nanoparticles and carbon nanotubes are internalized in roots and transferred to shoot of both wheat and rapeseed upon hydroponics exposure. TiO2 nanoparticles can also be internalized upon exposure in soil and even after an aerial contamination. TiO2 nanoparticles are accumulated in plants up to few hundred mg Ti/kg DM, their crystal phase is not modified and they do not dissolve during their transfer inside plants. CNT are less accumulated, up to few hundred µg NTC/kg DM, and seem to be altered by their transfer to and though plants.The nanomaterials we studied have very limited impact on plant development and physiology. One test out of eight has shown modulation after nanomaterial exposure: root elongation was induced when exposed to very small of both nanomaterials. Finally, we show that the nominal diameter of nanomaterials is negatively correlated with their internalization, transfer to shoot and induction of root elongation: the finest the nanomaterial, the highest their accumulation and impact on plant development.

La nanochimie et l’auto-assemblage sont des voies prometteuses de fabrication de matériaux nanostructurés aux propriétés optiques innovantes dans le domaine visible. Dans cette étude, des nanocomposites plasmoniques anisotropes sont formulés en introduisant sélectivement des nanoparticules métalliques dans des phases ordonnées de copolymères diblocs symétriques selon différentes stratégies d’incorporation. Pour la stratégie de post-incorporation, des nanoparticules d’or présynthétisées en milieu aqueux sont introduites sélectivement dans des phases pré-ordonnées d’un copolymère dibloc amphiphile. L’incorporation directe consiste àmélanger des nanoparticules d’or présynthétisées et un copolymère dibloc dans un solvant commun.La synthèse in situ de nanoparticules consiste à réduire des précurseurs métalliques préalablement introduits dans un des deux blocs d’un copolymère via une étape de réduction. Nous étudions, en particulier, comment la taille des nanoparticules d’or et leur fraction volumique influencent la nanostructure et les propriétés optiques de ces films nanocomposites. La morphologie des films macroscopiques est étudiée par microscopie électronique à transmission et diffusion des rayons Xaux petits angles. Les films minces de nanocomposites sont caractérisés structurellement parmicroscopie à force atomique, microscopie électronique à transmission et réflectivité des rayons X. Les indices optiques déterminés par ellipsométrie spectroscopique peuvent être décrits par un modèle de Maxwell-Garnett, prenant éventuellement en compte de façon phénoménologique les effets de couplage entre nanoparticules d’or. / Nanochemistry and self-assembly are promising ways to fabricate nanostructuredmaterials with innovative optical properties for visible light. In this work, anisotropic plasmonicnanocomposites are formulated by selectively introducing metallic nanoparticles in ordered phasesof symmetric dibloc copolymers with different strategies. For the strategy of post-incorporation, presynthesizedgold nanoparticles in aqueous medium are selectively introduced in pre-ordered phasesof an amphiphilic dibloc copolymer. Direct incorporation consists in mixing pre-synthesized goldnanoparticles and dibloc copolymer in a common solvent. In situ synthesis of nanoparticles consistsin reducing metallic precursors previously introduced in one of two blocks of a copolymer via areduction step. The influence of the size and the volume fraction of gold nanoparticles on thenanostructure and the optical properties of the nanocomposite films have been particularly studied.Morphology of macroscopic films is studied by transmission electron microscopy and small angle Xrayscattering. The nanocomposite thin films are structurally characterized by force atomicmicroscopy, transmission electron microscopy and X-ray reflectivity. The optical indices obtained byspectroscopic ellipsometry can be described with Maxwell-Garnett models, which can take intoaccount phenomenologically the effects of coupling between gold nanoparticles.

Nanoobjekte werden als eines der meist untersuchten Forschungsgebiete unserer Zeit immer beliebter in der Industrie, da durch Variation ihrer Strukturen besondere Eigenschaften entlockt werden können, die bei makrokristallinen Kompositionen nicht auftreten. Doch mit Zunahme der Anwendungsbereiche steigt wiederum die Wahrscheinlichkeit einer hohen Exposition, was die toxikologischen Untersuchungen der letzten Jahre bedingte. Allerdings wurden dabei weniger die kausalen Zusammenhänge eruiert. In dieser Arbeit zeigt der Autor die Beziehungen zwischen ZnO-Toxizität und intrazellulärer Zn2+-Konzentrationen auf. Zu diesem Zweck erfolgten Zytotoxizitätsuntersuchungen mittels MTT-Test von ZnO-Nanopartikeln und ZnCl2. Dadurch konnten die toxischen Eigenschaften dieser Agenzien belegt werden. Sowohl Nanopartikel als auch Zn2+ weißen in äquivalenter Gesamtmasse dieselben Toxizitätswerte auf. Nachfolgend wurde die Toxizität I) der Partikel durch Chelatierung der Ionen und II) der freigesetzten Zn2+ durch Abzentrifugieren der Partikel untersucht. Hierbei zeigte sich eine deutlich niedrigere Toxizität der Partikel in Abwesenheit von Zn2+. Hingegen verursachten die partikelfreien Proben allein durch die freigesetzten Zn2+ durchaus vergleichbare Effekte wie die ZnO-Dispersion. Erwähnenswert ist, dass generell eine geringere Toxizität durch FKS-Zugabe vorhanden war. Im Weiteren wurde die intrazelluläre Zn2+-Konzentration in Abhängigkeit der Zinkexposition untersucht. Anhand der Markierung mit dem zinkspezifischen Fluorophor FluoZin-3 erfolgte die quantitative Zn2+-Bestimmung mittels Durchflusszytometrie. Dabei ergab sich ein signifikanter Anstieg der intrazellulären Zn2+-Konzentration, der eine einschneidende Störung der Zinkhomöostase darstellt. Bemerkenswert ist der Anstieg in vitalen Zellen auf ein Vielfaches der Ausgangkonzentration, wobei das Überschreiten von etwa 10 nM zum Übergang in die Nekrose führte. Unabhängig von äußeren Faktoren lagen bei gleichen Toxizitätswerten vergleichbare intrazelluläre Zn2+-Konzentrationen vor. Offenbar gibt es einen direkten Zusammenhang zwischen intrazellulären Zn2+ und der Toxizität. Dieser Sachverhalt kann zur Risikobewertung der Nanopartikel herangezogen werden.

<div>The evaporation of a liquid drop containing particles resting on a substrate have diverse industrial applications including inkjet printing, spray coating, fabrication of functional nanomaterials, disease diagnosis, among others. In addition to these wide ranging practical applications, the sessile drop evaporation can be observed in everyday life with dew drops, coffee spills, and the dry patterns of other beverages.</div><div><br></div><div>The self-assembly of particles during drop evaporation is a process that is affected by various factors, such as contact line (CL) behaviors, microfluidic flows, short-range interactions of particle-interface and particle-particle. Each of these factors are complicated enough to study, let alone the total effects on the process. The primary goal of this work is to investigate the influence of microfluidic flows and the particle-interface interaction, viz. the evaporation process was subject to a pinned CL and the particle-particle interaction was neglected under dilute particle concentration. </div><div>To accomplish this goal, the Galerkin/Finite Element Method (G/FEM) is used to solve for the flow, the temperature and the particle concentration profiles. </div><div><br></div><div><br></div><div>The complexity of the problems comes from various surface phenomena, one of which is the surface tension. The surface tension brings capillary force in the normal direction and capillary flow toward the CL, which results in the well-known coffee-ring effect. Moreover, the surface tension changes with temperature, surfactant concentration, etc. resulting in Marangoni stresses in the tangential direction. The Marangoni stress on the surface leads to circulations of flow inside the drop and the circulation can be either clockwise or counterclockwise depending on the direction of the stress. </div><div><br></div><div>When the Marangoni stress is merely caused by temperature change, the circulation direction changes not only in time but also in space. At late stage of evaporation, i.e. with a small contact angle (CA), multi-circulation flow profiles emerge. This flow profiles are featured with stagnation points and transition points. The stagnation points can be further categorized into capillary-induced stagnation points and Marangoni-induced stagnation points. By introducing the concept of capillary-induced stagnation points, the simulations reached agreement with experiments in terms of the radial location of the observed stagnation points.</div><div><br></div><div><br></div><div>The multi-circulation flow profiles implied regional segregation inside the drop. When a large circulation is observed in most part of the drop and a small circulation exists near the CL, particle concentrations are relatively uniform in each individual region but differs significantly across the two regions. Transition points are used to characterize the location of the regional segregation, which can be adjusted by Marangoni stress.</div><div><br></div><div><br></div><div>Marangoni circulations in different directions revealed distinct influences on particle distribution and deposition. First, while both directions facilitate even distribution of particles, a clockwise circulation strengthens CL accumulation for a small Marangoni stress. Second, a counterclockwise circulation with a small Marangoni stress impedes the deposition rate of particles, while a clockwise circulation facilities the deposition no matter how small the Marangoni stress is. This results is under a condition of a strong adsorption between particles and substrates. </div><div><br></div><div>The analysis and understanding of the above results are crucial to elucidating and controlling the final deposition patterns of particles. Thus, the focus of this research is to understand the combined effect of Marangoni stress and capillary flow on particle deposition during sessile drop evaporation.</div><div><br></div>

<p></p><p>Flexible electronics involve electronic circuits fabricated on flexible substrates. They have promising applications in wearable devices and flexible sensors etc. and have thus attracted much research interest in recent years. The working environment of flexible electronic devices may require them to go through repeating deformations, during which cracks may generate and grow in the metallic components of the devices, reducing service life of these devices. To address such challenges, it is desirable to investigate methods to improve the reliability of flexible electronics in these working conditions. </p> <p>This research reported here will focus on topics related to laser-based fabrication of carbon nanotube-metal composites on flexible substrates: </p> <p>Experimental studies were carried out to investigate the structures and properties of carbon nanotube – metal composites produced by a laser-based fabrication process on flexible substrates. Extensive characterizations and testes were carried out, including measurements of electrical resistivity of laser-sintered material, characterizations with SEM, TEM, EDS and XPS, and mechanical performance tests (bending fatigue test, static tensile test and adhesion test). The experimental study suggests that the laser-fabricated metal composites have promising potentials to help enhancing reliability and durability of metal components in flexible electronic devices. </p> <p>A molecular dynamics model was also developed to study the coalescence of metal nanoparticles (gold NPs in this study) around the end of a multi-walled carbon nanotube (MWCNT) and their interaction with the CNT at elevated temperatures. The MD model was first tested by comparing the MD-predicted NP melting points with experiment-deduced results from the literature. Then the coalescence of five 3-nm Au NPs around the end of a MWCNT and their interactions with the CNT were studied with MD simulations. The molecular system was studied under different elevated temperatures and for different carbon nanotube diameters, and the simulation results were analyzed and discussed. </p><br><p></p>