Cerium Oxide Nanoparticles (CeO2-NPs) are commonly used in polishing, engine enhancement agents and many other commercial products. Increased applications and accidental release have raised concerns on the potential impact of CeO2-NPs on the environment. Most previous studies focused on the short term effect of CeO2-NPs. Information is severely lacking on the long-term impact of CeO2-NPs at environmentally relevant concentrations. The main goal of the current dissertation was to investigate the chronic phytotoxicity of CeO2-NPs on two plant species, tomato (Solanum lycopersicum L.) and Turnip mustard (Brassica rapa L.) fast growing variety, and the physiological and biochemical responses of these two plant species to CeO2-NPs. Four specific objectives were established. The first objective was to investigate the effects of combined CeO2-NPs and TiO2-NPs exposure on tomato plant growth and oxidative stress. The second objective was to investigate the impact of a lifecycle exposure to CeO2-NPs on wild type tomato growth and fruit yield and to evaluate the transgenerational effects of CeO2-NPs exposure on plant growth and the oxidative stress of the second generation tomato seedlings. The third objective was to compare the influence of CeO2-NPs and bulk CeO2 particles on plant growth and oxidative stress of standard fast growing Brassica rapa. The final objective was to evaluate the risks of CeO2-NPs exposure over three generations on Brassica plant growth, oxidative stress and reproduction. The results suggested that firstly, CeO2-NPs pre-exposure at concentrations of 4 and 40 mg/kg dry soil followed by 1000 mg/L of TiO2-NPs post-treatment increased H2O2 content and antioxidant proteins activities compared with CeO2-NPs alone and TiO2-NPs alone, and reduced biomass of the tomato plants compared with CeO2-NPs alone. Secondly, irrigation of CeO2-NPs at concentrations up to 10 mg/L stimulated wild type tomato plant growth, but exposure to CeO2-NPs over a lifecycle harmed plant growth and induced higher H2O2 content in tomato seedlings of the second generation. Thirdly, bulk CeO2 exposure at irrigation concentrations of 10, and 100 mg/L were more beneficial for Brassica rapa plant growth than CeO2-NPs at equivalent concentrations. CeO2-NPs irrigation at 10 and 100 mg/L increased H2O2 content and antioxidant proteins activities than bulk CeO2 at equivalent concentrations. However, the mustard plants treated by CeO2-NPs or bulk CeO2 showed changes of H2O2 content in different growth stages, which illustrated that CeO2-NPs and the bulk counterpart induced the change of H2O2 content differently. Finally, irrigating mustard plants with 10 to 1000 mg/L CeO2-NPs over three generations resulted in an inhibited plant growth, stronger oxidative stress, less seed yield and poorer reproduction of offspring plants. To our knowledge, this is the first report on the chronic (multigenerational) effects of CeO2-NPs on plant growth and oxidative stress of tomato and mustard plants grown in soil.

The objective of this research was to study the catalytic graphitization of cellulose fibers coated with iron oxide nanoparticles. Bleached cellulose fibers and iron oxide nanoparticles coated cellulose fibers were pyrolyzed at five elevated temperatures. The crystallographic structures of carbon-encapsulated iron oxide nanoparticles were then investigated by the following techniques: Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), and Selected-Area Electron Diffraction (SAED). The graphitization of cellulosic fibers was enhanced by the presence of iron oxide nanoparticles. Moreover, iron oxide nanoparticles deposited on cellulosic fiber samples pyrolyzed above 800°C produced graphitic structures. TEM and XRD were performed to identify and characterize the phase transitions of carbon-encapsulated iron oxide nanoparticles after pyrolysis treatment at four temperatures: 500°C, 800°C, 1000°C, and 1600°C. TEM of samples pyrolyzed at or above 800°C showed resulting units were core-shell structures consisting of dark grains and a light matrix with graphitic structure.

This study examines the use of unmodified magnetite nanoparticles (Fe3O4 NPs) for selective extraction and enrichment of the catecholamines dopamine (DA), noradrenaline (NE), and adrenaline (E), prior to analysis using capillary electrophoresis with UV detection. Coordination between Fe3+ on-the-surface Fe3O4 NPs and the catechol moiety of catecholamines enables Fe3O4 NPs to capture catecholamines from an aqueous solution. We obtained maximum loading of catecholamines on the NP surface by adjusting the pH of the solution to 7.0. In addition, catecholamine loading on the Fe3O4 NPs increased in conjunction with NP concentrations. Ligand exchange found H3PO4 to be efficient in the removal of adsorbed catecholamines on the NP surface. Adding 1.2% poly(diallyldimethylammonium chloride) to the background electrolyte caused efficient separation of the liberated catecholamines with baseline resolution within 20 min. Under optimal extraction and separation conditions, the limit of detections at a signal-to-noise ratio of 3 for E, NE, and DA were 9 nM, 8 nM, and 10 nM, respectively. Significantly, we successfully used the combination of a phenylboronate-containing spin column and the proposed method to determine the concentrations of NE and DA in urine and the content of NE in Portulaca oleracea L. leaves.

We have studied a continuous aerosol process for producing oxide nanoparticles with sizes of 10-60 nm that are decorated with smaller 1-3 nm metallic nanoparticles. Such particles may be useful in a number of areas including catalysis and as contrast enhancement agents in biomarkers. To produce the oxide nanoparticle carriers, an aerosol of 1-10 [micrometer] oxide particles are ablated using an excimer laser. The resulting oxide nanoparticle aerosol is then mixed with 1-2 [micrometer] metallic particles and this mixed aerosol is ablated a second time. The oxide nanoparticles are too small to ablate but act as seeds for the nucleation of metallic nanoparticles on the surface of the oxide. The nanoparticle sizes can be varied by changing the gas type or gas pressure in the aerosol. We demonstrate the feasibility of such an approach using two oxides, SiO₂ and TiO₂, and two metals, Au and Ag. / text

Cerium oxide (ceria, CeOâ‚‚) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus acting as an anti-oxidant. This phenomenon has been explained based on the autocatalytic property of ceria NPs. Several methods have been developed for the synthesis of ceria NPs that include flame combustion, hydroxide co-precipitation, hydrothermal/solvothermal, microemulsion, sonochemical and microwave-assisted heating methods and sol-gel method. Ceria NPs synthesized by these methods are often highly aggregated. Furthermore, large scale synthesis of monodispersed CeOâ‚‚ NPs is quite challenging. Therefore it is desirable to synthesize ceria NPs in bulk quantity keeping its important properties intact, specifically free-radical scavenging property. The main goal of this study is therefore to synthesize ultra-small ([less than]5.0 nm), high quality monodispersed ceria NPs in large quantities. In this thesis work, I present a couple of room temperature techniques, dilute sodium hydroxide (NaOH) assisted and ethylenediamine (EN) assisted for the synthesis of nearly mono-dispersed, ultra-small ( < 5 nm) and water-dispersible ceria NPs. Morphology and particle size of the ceria NPs were investigated through high resolution transmission electron microscopy (HRTEM). The HRTEM analysis confirmed the formation of 3.0 ± 0.5 nm size and 2.5 ± 0.2 nm size highlycrystalline ceria NPs when synthesized using dilute NaOH and EN as solvents, respectively. The nanostructures were characterized by X-ray diffraction (XRD) studies to determine the crystal structure and phase purity of the products. The samples were also thoroughly characterized by X-ray photoelectron spectroscopy (XPS) to determine the oxidation state of cerium ions. The presence of the +3 and +4 oxidation states in the samples was also confirmed from the XPS analysis. The co-existence of these two oxidation states is necessary for their applications as free radical scavenger. The autocatalytic behaviors of the ceria NPs were investigated through a hydrogen peroxide test and monitored by UV-visible transmission spectroscopy.

Nanoparticles (NP) offer great merits over controlling thermal, chemical and physical properties when compared to their micro-sized counterparts. The effectiveness of the dispersion of the NP is the key aspect of the applications in nanotechnology. The project studies the characterization and modification of functional NPs aided by the means of large scale molecular thermal dynamic computerized dispersing simulations, in the level of Nanoclusters (NC). Carrying out NP functionality characterisation in fluids can be enhanced, and analysed through computational simulation based on their interactions with fluidic media; in terms of thermo-mechanical, dynamic, physical, chemical and rheological properties. From the engineering perspective, effective characterizations of the nanofluids have also been carried out based on the particles sizes and particle-fluids Brownian motion (BM) theory. The study covered firstly, investigation of the pure CuO NP diffusion in water and hydrocarbon fluids, secondly, examination of the modified CuO NP diffusion in water. In both cases the studies were put under experiments and simulations for data collection and comparison. For simulation the COMPASS forcefield, smoothed particle hydrodynamic potential (SPH) and discrete particle dynamics potential (DPD) were implemented through the system. Excellent prediction of BM, Van der Waals interaction, electrostatic interaction and a number of force-fields in the system were exploited. The experimental results trend demonstrated high coherence with the simulation results. At first the diffusion coefficient was found to be 1.7e-8m2/s in the study of CuO NC in water based fluidic system. Secondly highly concurrent simulation results (i.e. data for viscosity and thermal conductivity) have been computed to experimental coherence. The viscosity trend of MD simulation and experimental results show a high level of convergence for temperatures between 303-323K. The simulated thermal conductivity of the water-CuO nanofluid was between 0.6—0.75W•m−1•K−1, showing a slight increase following a rise in temperature from 303 to 323 K. Moreover, the alkane-CuO nanofluid experimental and simulated work was also carried out, for analysing the thermo-physical quantities. The alkane-CuO nanofluid viscosity was found 0.9—2.7mpas and thermal conductivity is between 0.1—0.4W•m−1•K−1. Finally, the successful modification of the NPs on experimental and simulation platform has been analysed using different characterization variables. Experimental modification data has been quantified by using Fourier Transformation Infrared (FTIR) peak response, from particular ranges of interest i.e. 1667-1609cm-1 and 1668-1557cm-1. These FTIR peaks deduced Carboxylate attachment on the surface of NPs. Later, MD simulation was approached to mimic experimental setup of modification chemistry and similar agglomerations were observed as during experimental conditions. However, this approach has not been presented before; therefore this study has a significant impact on describing the agglomeration of modified NPs on simulation and experimental basis. Henceforth, the methodology established for metal oxide nanoparticle dispersion simulation is a novelty of this work.

An essential component of developing successful neural stem cell (NSC)-based therapies involves the establishment of methodologies to noninvasively monitor grafted NSCs within brain tissues in real time. In this context, ex vivo labeling with ultrasmall superparamagnetic iron oxide (USPIO) particles has been shown to enable efficient tracking of transplanted NSCs via magnetic resonance imaging (MRI). However, whether and how USPIO labeling affects the intrinsic biology of NSCs is not thoroughly understood, and remains an active area of investigation. Here, we perform a comprehensive examination of rat NSC survival and regenerative function upon labeling with the USPIO, Molday ION Rhodamine B (MIRB), which allows for dual magnetic resonance and optical imaging. After optimization of labeling efficiency, two specific doses of MIRB (20 and 50 mu g/mL) were chosen and were followed for the rest of the study. We observed that both MIRB doses supported the robust detection of NSCs, over an extended period of time in vitro and in vivo after transplantation into the striata of host rats, using MRI and post hoc fluorescence imaging. Both in culture and after neural transplantation, the higher 50 mu g/mL MIRB dose significantly reduced the survival, proliferation, and differentiation rate of the NSCs. Interestingly, although the lower 20 mu g/mL MIRB labeling did not produce overtly negative effects, it increased the proliferation and glial differentiation of the NSCs. Additionally, application of this dose also changed the morphological characteristics of neurons and glia produced after NSC differentiation. Importantly, the transplantation of NSCs labeled with either of the two MIRB doses upregulated the immune response in recipient animals. In particular, in animals receiving the 50 mu g/mL MIRB-labeled NSCs, this immune response consisted of an increased number of CD68(+)-activated microglia, which appeared to have phagocytosed MIRB particles and cells contributing to an exaggerated MRI signal dropout in the animals. Overall, these results indicate that although USPIO particles, such as MIRB, may have advantageous labeling and magnetic resonance-sensitive features for NSC tracking, a further examination of their effects might be necessary before they can be used in clinical scenarios of cell-based transplantation.

The main challenge in disease treatment is no more the discovery of new therapeutic drugs, but to provide targeted delivery of therapeutic drugs to specific sites without incurring systemic toxicity effects. An efficient way of reducing the toxicity is by encapsulating the drug with a biodegradable matrix that can provide controlled release of the drug along with local heating of the drug. Local heating can be obtained by incorporating magnetic iron oxide particles that heat upon exposure to AC electromagnetic fields. The magnetic iron oxide nanoparticles are also gaining much attention as MRI contrast agents. Thus it would be of potential benefit if a drug delivery system is designed to encapsulate the drug as well as the magnetic iron oxide nanoparticles within a biodegradable matrix, thereby providing a dual modal imaging and therapeutic delivery system. The key step in the design of a dual modal drug delivery system is the encapsulation of the magnetic iron oxide nanoparticles with polymer of choice. The magnetic iron oxide nanoparticles were encapsulated into a robust poly (styrene-co-vinylbenzylchloride-co-divinylbenzene) (PSVBDVB) to study these synthetic variations upon encapsulation with a polymer. The next step to the design of drug delivery system was to replace the PSVBDVB polymer by a biocompatible and biodegradable polymer- Poly (lactide-co-glycolide) (PLGA). The PLGA composites containing the Fe@FeOx core shell nanoparticles and the drug analog [Ru(bpy) dye] was prepared by oil-in water emulsion solvent evaporation technique. The local heating of the PLGA composites was also achieved by irradiating the Fe@FeOx nanoparticles with 2.45 GHz microwave radiations. Higher Ru(bpy) dye release from the composites by locally heating the sample with 2.45 GHz microwave pulse compared to externally heating the composite sample was achieved. The final step was the design of controlled release drug delivery system with dual modal imaging and therapeutic capabilities. To obtain narrow sized PLGA composites the Fe@FeOx nanoparticles were replaced by chloroform based ferrofluid. The ferrofluid was synthesized by novel thermolysis technique. The release of the dye from the PLGA composites when placed in the Rf induction coil was determined by fluorescence spectroscopy and a linear increase in the fluorescent intensity was observed with time. Also, the controlled release of the dye from the composites was achieved by a pulsed Rf treatment. Magnetic resonance imaging was also performed using the PLGA composites which showed enhancement in the T2-weighted image contrast and thus negligible reduction in the contrast capabilities of the iron oxide particles (R2 = 58.7 s-1mM-1). The PLGA composites containing the drug analog and the iron oxide nanoparticles thus constitute a controlled release drug delivery system with dual modal imaging and therapeutic capabilities.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Graphene oxide (GO) is a single carbon layer, oxygen bearing graphene derivative, containing hydroxyl and carboxyl groups. Graphene oxide nanoparticles (GONPs) are promising nanomaterials for a variety of applications such as electrochemical analysis, adsorption of biomolecules, biosensors and drug and vaccine delivery systems. While these newly engineered nanoparticles hold great potential for developments in industry and medicine, the widespread use of these material will inevitably result in GO residues in the environment where they could possibly pose a risk to human and wildlife health. Interaction of the nanoparticles and biota can affect numerous biological processes. In humans they can affect any of the physiological systems such as the immune, endocrine, reproductive and cardiovascular systems. Although studies have indicated that GO exposure cause increased reactive oxygen species in cells, they mechanisms whereby GO act on the cell are still poorly understood. A few studies have investigated the effects of GONP and other graphene nanoparticle derivatives on the immune system. The aim of this study was to investigate the in vitro effects of GONPs on the immune system by the exposure of the murine macrophage cell line, RAW 264.7, to different concentrations of GONPs.

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