La production à l'échelle industrielle et la diversité d'utilisation des nano-objets manufacturés, leurs agrégats et agglomérats (NOAA) et leur possible libération dans l'environnement aquatique naturel ont conduit à une préoccupation croissante parmi la communauté scientifique des sciences de l'environnement et des nanotechnologies. Parmi eux, les ciments photocalytiques sont basés sur la propriété photocatalytique de NOAA-TiO2 ajoutés dans la matrice du ciment. Lors de l'exposition au rayonnement UV, les NOAA-TiO2 provoquent l‘oxydation (i.e. dégradation) des composés adsorbés à la surface du ciment. Sa validation environnementale est requise, en termes d'impacts et risques associés à l'incorporation des NOAA-TiO2. Le but de cette étude est de déterminer les mécanismes de relargage des NOAA-TiO2 incorporés dans le ciment autonettoyant durant le processus de vieillissement et d’identifier les paramètres qui pourraient le contrôler. Les éléments relargués (fractions particulaires et solubles) et leurs cinétiques ont été quantifiés par ICP-OES et caractérisés par MET. Nous avons ensuite analysé la phase solide (du cœur à la couche altérée) en utilisant plusieurs techniques aux rayons X, la DRX (diffraction des rayons X), μ-XRF (micro X-Ray spectroscopie) et une combinaison sans précédent de nano et micro X-ray tomographie pour effectuer une caractérisation complète de la matrice du ciment altéré comprenant la structure de pores. / The industrial scale production and wide variety of applications of manufactured nano-object, their aggregates and agglomerates (NOAA) and their possible release into the natural aquatic environment have produced an increasing concern among the nanotechnology and environmental science community.Among them, the photocatalytic cements are based on the photocatalytic property of TiO2-NOAA added in the cement matrix. During continuous UV radiation exposure, TiO2-NOAA lead to the oxidation (i.e. degradation) of compounds adsorbed at the cement surface. Such NOAA application in building construction is promising as it exhibits improved properties but its environmental validation (in terms of impacts and risks associated with the incorporation of TiO2 NOAA) is also required.The aim of this study is to determine the mechanisms of TiO2-NOAA release from a self-cleaning cement during aging process and to identify cement parameters controlling it.. The elements released (particulate and soluble fractions) and their kinetic were quantified by ICP-OES and characterized with TEM. We analyzed the solid phase (core to altered layer) using several X-ray based techniques: XRD (X-Ray Diffraction), µ-XRF (micro X-Ray Spectroscopy) and an unprecedented combination of nano and micro X-ray computed tomography to perform a original and omplete altered cement matrix characterization including pore structure.

The overall goals of this doctoral dissertation are to provide knowledge of workers' exposure to nanomaterials and to assist in the development of standard methods to measure personal exposure to nanomaterials in workplace environments. To achieve the first goal, a field study investigated airborne particles generated from the weighing of bulk carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. This study also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood and biosafety cabinet) for control of exposure to particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured with direct-read instruments, and particle morphology was determined by electron microscopy. Sanding of CNT-epoxy nanocomposites released respirable size airborne particles with protruding CNTs very different in morphology from bulk CNTs that tended to remain in clusters (>1µm). Respirable mass concentrations in the operator's breathing zone were significantly greater when sanding took place in the custom hood (p <0.0001) compared to the other LEV conditions. This study found that workers' exposure was to particles containing protruding CNTs rather than to bulk CNT particles. Particular attention should be placed in the design and selection of hoods to minimize exposure. Two laboratory studies were conducted to realize the second goal. Collection efficiency of submicrometer particles was evaluated for nylon mesh screens with three pore sizes (60, 100 and 180 µm) at three flow rates (2.5, 4, and 6 Lpm). Single-fiber efficiency of nylon mesh screens was then calculated and compared to a theoretical estimation expression. The effects of particle morphology on collection efficiency were also experimentally measured. The collection efficiency of the screens was found to vary by less than 4% regardless of particle morphology. Single-fiber efficiency of the screens calculated from experimental data was in good agreement with that estimated from theory for particles between 40 and 150 nm but deviated from theory for particles outside of this range. New coefficients for the single-fiber efficiency model were identified that minimized the sum of square error (SSE) between the experimental values and those estimated with the model. Compared to the original theory, the SSE calculated using the modified theory was at least threefold lower for all screens and flow rates. Since nylon fibers produce no significant spectral interference when ashed for spectrometric examination, the ability to accurately estimate collection efficiency of submicrometer particles makes nylon mesh screens an attractive collection substrate for nanoparticles. In the third study, laboratory experiments were conducted to develop a novel nanoparticle respiratory deposition (NRD) sampler that selectively collects nanoparticles in a worker's breathing zone apart from larger particles. The NRD sampler consists of a respirable cyclone fitted with an impactor and a diffusion stage containing eight nylon- mesh screens. A sampling criterion for nano-particulate matter (NPM) was developed and set as the target for the collection efficiency of the NRD sampler. The sampler operates at 2.5 Lpm and fits on a worker's lapel. The cut-off diameter of the impactor was experimentally measured to be 300 nm with a sharpness of 1.53. Loading at typical workplace levels was found to have no significant effect (2-way ANOVA, p=0.257) on the performance of the impactor. The effective deposition of particles onto the diffusion stage was found to match the NPM criterion, showing that a sample collected with the NRD sampler represents the concentration of nanoparticles deposited in the human respiratory system.

In this project the adsorption ability of mesoporous magnesium carbonate (MMC) for copper (Cu), cobalt (Co), chromium (Cr) and arsenic (As) was evaluated. This was done by mixing MMC and dissolved metal (of different concentrations) and measuring the concentration of the solution before and after addition of MMC with Inductively coupled plasma optical emission spectroscopy. Besides MMC, “ordinary” magnesium carbonate (MgCO_3) was evaluated for comparison. Furthermore, the MMC was characterised with various instruments before and after adsorption of the metals. The adsorption experiments established that MMC was able to adsorb large amounts of Cu, Co and As while MgCO_3 was not. Moreover, it was discovered that both materials adsorbed equally large amounts of Cr. At higher concentrations of Cu and Co the uptake capacity of MMC suddenly dropped. However, for As, it was determined that MMC reached saturation at a concentration of ~22 mg/L. An adsorption experiment of a mixture of metals of 20 mg/L of each metal could not conclude anything about the selectivity of MMC, but the experiment revealed that MMC was able to adsorb all of Cu, Co and As rapidly at this concentration. The characterisation of MMC before adsorption revealed an amorphous structure and a high porosity. The structure of MMC after adsorption of Cu went from amorphous to crystalline and after adsorption of Co and As the structure also became crystalline, but of a lower degree than after adsorption of Cu. Furthermore, it was discovered that ion exchange also occurred along with adsorption.

京都大学 / 新制・論文博士 / 博士(工学) / 乙第13407号 / 論工博第4193号 / 新制||工||1762(附属図書館) / (主査)教授 安部 武志, 教授 作花 哲夫, 教授 阿部 竜 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The mapping of the refractive index of cells has been extensively studied since 1950s. This optical parameter constitutes a key biophysical property strongly correlated to fundamental cell parameters such, e.g., intracellular mass distribution and protein concentration. Experimental studies evidence that the cell refractive index (Refractive Index) provides critical insights to understand diverse cellular structures and interpret pathological states, including diverse stages of diseases. However, measuring the refractive indices of biological specimens satisfying clinical requirements is currently challenging, since there is a lack of spectral signatures of sub-cellular components in the visible range due to their transparent nature. Designing methods capable of extracting visible fingerprints of cellular components remains attracting large research interests. In this work, I have contributed to this project by fabricating and characterizing a black nanostructured membrane that dynamically interacts with cancerous cells and furnishes label-free structural color generation by exploiting the inherent contrast mechanisms of them. Thus, adequately meeting morphology differentiation to assist in biomedical research. I have tested the system with HCT116 colorectal cancer cells. In addition, this special membrane allows refractive index recovery and cell thickness mapping with commonly available bright-field microscopy equipment. Therefore, it is of considerable clinical importance to allow the generation of qualitative information about cell morphology to add in medicine and biophysics research.

Useful properties render titanium dioxide nanomaterials (NMs) to be one of the most commonly used NMs worldwide. TiO2 powder is used as food additives (E171), which may contain up to 36% nanoparticles. Consequently, humans could be exposed to comparatively high amounts of NMs that may induce adverse effects of chronic exposure conditions. Visualization and quantification of cellular NM uptake as well as their interactions with biomolecules within cells are key issues regarding risk assessment. Advanced quantitative imaging tools for NM detection within biological environments are therefore required. A combination of the label-free spatially resolved dosimetric tools, microresolved particle induced X-ray emission and Rutherford backscattering, together with high resolution imaging techniques, such as time-of-flight secondary ion mass spectrometry and transmission electron microscopy, are applied to visualize the cellular translocation pattern of TiO2 NMs and to quantify the NM-load, cellular major, and trace elements in differentiated Caco-2 cells as a function of their surface properties at the single cell level. Internalized NMs are not only able to impair the cellular homeostasis by themselves, but also to induce an intracellular redistribution of metabolically relevant elements such as phosphorus, sulfur, iron, and copper.

Computational investigations on semiconductor (silicon or germanium) clusters (Sinor Gen) in combination with transition metal (M) impurities are reviewed in this contribution. Emphasis is placed on investigations that focus on the size evolution features of MmSi n(or MmGen) such as the critical ligand number for the transition from exohedral to endohedral equilibrium geometry. Geometric, energetic, electronic, and magnetic characteristics of MmSi n or MmGen systems are discussed. It is pointed out that selected MmSin systems with n = 12 and n = 16 and MmGen with n = 10 or 12 and n = 16 emerge from present computational research in the size region of n ≤ 20 as the most promising candidates for building blocks of novel nanomaterials. In addition, comparison is made between MmSin and MmGen clusters.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18693号 / 工博第3971号 / 新制||工||1611(附属図書館) / 31626 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 北川 進, 教授 梅田 眞郷, 教授 濵地 格 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

[pt] A hidroxiapatita está entre os biomateriais cerâmicos de maior interesse na área médica, pois, além da sua semelhança com a fase inorgânica dos ossos e dentes, apresenta exelente biocompatibilidade e bioatividade. Devido a sua ampla aplicação e aos gastos inerentes a utilização de implantes em processos cirúrgicos, torna-se necessário o desenvolvimento de processos mais viáveis encomonicamente e de materiais com melhores propriedades, com isso, este trabalho teve como objetivo a síntese de hidroxiapatita (HAp) pelo método de precipitação utilizando cascas de ovos de galinha como fonte de cálcio na presença de diferentes concentrações de sacarose, para avaliar sua influência nas características dos materiais sintetizados. A utilização da casca de ovo surge como um insumo atrativo, uma vez que é composta majoritariamente por carbonato de cálcio, um material abundante e barato. A casca de ovo foi calcinada à 1000 graus Celsius para obtenção do CaO que foi hidrolisado para a obtenção do Ca(OH)2.Os materiais foram obtidos pela reação de precipitação entre o Ca(OH)2 e H3PO4 a temperatura ambiente e com controle de pH, utilizando diferentes quantidades de sacarose. Os materiais obtidos foram caracterizados pelos métodos de Difração de Raios X (DRX), Microscopia Eletrônica de Varredura com emissão de campo (MEV-FEG), adsorção de N2 a 77K (BET), Microscopia Eletrônica de Transmissão (MET), espectroscopia de infravermelho com transformada de Fourier (FTIR), análise termogravimétrica (TG) e Fluorescência de Raios X (FRX). Os resultados de DRX confirmaram a formação da HAp. O FTIR apresentou as bandas correspondentes a HAp, corroborando os resultados de DRX, identificando também bandas de carbonato. Os resultados de EDXS confirmaram a composição química das amostras, sendo esta de P, O e Ca. A caracterização por MEV permitiu a avaliação da mudança da morfologia com o para as diferentes da quantidade de sacarose utilizada, sendo observada uma tendência a formação de partículas esferoidais. Os resultados de BET evidenciaram um aumento de superfície específica com o aumento da quantidade de sacarose, passando de 36 para 93 m2/g, decorrente do aumento de porosidade e diminuição do tamanho de partícula, resultado confirmado pelo MET, com tamanho de partícula passando 50 nm para valores em torno de 10-20 nm. Para avaliação da citotoxicidade foi realizado o ensaio da redução da resazurina para o período de 24h. Os resultados obtidos indicaram que as amostras são não citotóxicas. O ensaio de bioatividade foi realizado em meio McCoy para o período de 3 e 7 dias, apresentando resultados de dissolução das amostras compatíveis com caracteríticas de superfícies bioativas, porém, para o período de da análise, não foi observada a formação da camada bone like apatite. Os materiais sintetizados apresentaram propriedades semelhantes aos obtidos a partir de fontes de cálcio comerciais, apresentando promissor potencial em aplicações da engenharia de tecido ósseo, além de contribuir para a reciclagem desses bio-resíduos que é a casca de ovo. Os resultados obtidos indicam que a sacarose pode alterar as características do material, sendo um promissor aditivo/template de fácil obtenção e baixo custo, proporcionando materiais com elevada superfície específica e redução do tamanho de partícula. / [en] Hydroxyapatite is among the ceramic biomaterials of greatest interest in the medical field, because, in addition to its similarity with the inorganic phase of bones and teeth, it presents excellent biocompatibility and bioactivity. Due to its wide application and the expensive surgical processes, it is necessary to develop more viable processes and materials with better properties, therefore, the work aimed the hydroxyapatite synthesis (HAp) by precipitation method using hen’s eggshells as a calcium source in the presence of different sucrose concentrations, to evaluate its effect on the characteristics of the synthesized materials. A comparative study was also carried out with HAp samples obtained without sucrose and with commercial Ca(OH)2. The use of eggshells appears as an attractive raw material since it is mainly composed of calcium carbonate and because it is an abundant and cheap material. The eggshell was calcined at 1000 Celsius to obtain CaO, which was hydrolyzed to obtain Ca(OH)2. The materials were obtained by the precipitation reaction between Ca(OH)2 and H3PO4 at room temperature with pH control, using different amounts of sucrose. The obtained materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy with field emission (SEM-FEG), N2 to 77K adsorption (BET), Transmission Electron Microscopy (TEM), infrared spectroscopy with Fourier transform (FTIR), thermogravimetric analysis (TG) and X-Ray Fluorescence (XRF). The XRD results confirmed the formation of HAp. The FTIR showed the bands corresponding to HAp, corroborating the results of DRX, in addition to the presence of carbonate bands. The results of EDXS confirmed the composition of the samples, being of P, O and Ca. The SEM characterization allowed the evaluation of the morphology changes for the different amounts of the sucrose used, forming spheroidal particles. The BET results showed an increase in specific surface area with the rise in the sucrose amount, from 36 to 93 m2/g, due to the rise in porosity and decrease in particle size, a result confirmed by TEM, with particle size changing from 50 nm to values around 10-20 nm. The resazurin reduction assay was performed for the 24h period to evaluate of cytotoxicity. The results obtained indicate that the samples were non-cytotoxic. The bioactivity assay was carried out in McCoy medium for 3 and 7 days, showing dissolution results of the samples compatible with characteristics of bioactive surfaces. The formation of the bone-like apatite layer was not observed for the analysis period. The synthesized materials showed properties similar to those obtained from synthetic calcium sources. Therefore, it presents promising potential in bone tissue engineering applications, besides contributing to the recycling of this bio-residue, the eggshell. The high specific surface area and small particle size results obtained indicate that sucrose can be a promising additive/template that is easy to obtain at low cost.

Nano and nanostructured materials offer unique physical and chemical properties that differ considerably from their bulk counterparts. For decades, due to their fascinating properties, they have been extensively explored and found to be beneficial in numerous applications. These materials are key components in many cutting-edge optic and photonic technologies, including photovoltaics, waveguides and sensors. In this dissertation, the uses of nano and nanostructured materials for optical applications are investigated in the context of optical limiting, three dimensional displays, and optical sensing. Nanomaterials with nonlinear optical responses are promising candidates for self-activating optical limiters. In the first part of this study, optical limiting properties of unexplored nanomaterials are investigated. A photoacoustic detection technique is developed as an alternative characterization method for studying optical nonlinearities. This was done with an indigenously developed setup for measuring the photoacoustic signals generated from samples excited with a pulse laser. A theoretical model for understanding the experimental observations is presented. In addition, the advantages of this newly developed technique over the existing methods are demonstrated. Blending optical sensitizers with photoconducting polymers and chromophores results in a polymer composite that is able to record a light grating. This composite can be used as recording media in 3D holographic display technology. Here, 2D nano materials, like graphenes, are used as optical sensitizers to improve the response time of a photorefractive polymer. The addition of graphenes to a PATPD/ECZ/7-DCST composite results in a three-fold enhancement in response time and therefore faster recording speed of the medium. The faster build-up time is attributed to better charge generation and mobility due to the presence of graphenes in the composite. Lastly, a facile nanofabrication technique is developed to produce metallic nanostructures with a tunable plasmonic response. The enhancement of the light-matter interactions due to these nanostructures in sensing an analyte is demonstrated.