Carbon nanoparticles constitute a class of important materials that have uses in many different fields. This thesis focuses on the synthesis and surface modification of different carbon nanoparticles and each novel nanomaterial is demonstrated to have a specific sensing application. Carbon blacks play a significant role in the research that is presented herein. Emperor 2000, a commercial bulk-produced carbon black available from Cabot Corporation, is the starting material for many of the investigations. The surface of Emperor 2000 is shown to be susceptible to physisorption, through π-π stacking. These interactions are exploited to append pyrene-based compounds onto the surface of the carbon nanoparticles. This methodology results in carbon nanoparticles with surface boronic acid functionality that is demonstrated to be affective in the electrochemical detection of catecholic caffeic acid. Emperor 2000 carbon nanoparticles are commercially produced with phenylsulphonic acid functional groups on the surface. This functionality is subjected to synthetic methods to obtain carbon nanoparticles with extremely hydrohphobic character, which are demonstrated as important substrates for probing lipophilic redox systems and lipid character under different experimental conditions. Fluorescent carbon nanodots (C-dots) are another important form of carbon nanoparticle. Herein, the facile synthesis of C-dots that possess intrinsic pyridine functionality is described. These nanodots exhibit two-photon fluorescence that is exhibited both in solution and in HeLa cells. The nanodots are demonstrated to have the potential to be developed into nanomedicines and biocompatible scaffolds for new drug delivery mechanisms. These straightforward synthesis, modification, and application methods demonstrate the effectiveness and the versatility of carbon nanoparticles. This class of nanomaterial is generally outclassed by modern and more fashionable carbon nanotubes and graphene-based systems. However, carbon nanoparticles are more cost effective and readily available carbon-based nanomaterials that can be used for a wide range of applications.

Lignin is an undervalued product that does not yet provide economic returns. Finding value-added applications of lignin is needed to achieve economic sustainability. Carbon nanoparticles have great technological and industrial importance because of their enhanced physicochemical, electrical, thermal and mechanical properties. In this work a novel method has been explored to produce carbon nanoparticles from lignin. The objective of this work is to synthesize carbon nanoparticles with high surface area from lignin through the carbonization process. Lignin was dissolved in alkaline solutions with different weight ratios of lignin and potassium hydroxide. An intermediate sublimation process was adopted to reduce agglomeration of particles. The lignin was thermo-stabilized after the sublimation process in oxidizing atmosphere followed by the carbonization process in an inert atmosphere at 700oC using tubular furnace. The increase in glass transition tem-perature during thermo-stabilization process was confirmed by DSC analysis. The con-densation reactions during thermo-stabilization process were confirmed by FTIR analysis. The formation of carbon nanoparticles was confirmed by transmission electron microscopy (TEM) analysis. Carbon nanoparticles with high specific surface area of 42 m2/g were produced. From the DLS particle size distribution it was found that 5 wt% KOH is the optimum concentration for synthesizing carbon nanoparticles from lignin. / Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) New Directions Research Program for funding the project (number SR 225).

Carbon nanoparticles (CNPs) have drawn great attention in the last few years owing to their unique properties such as excellent water solubility, chemical stability, inertness, low toxicity, good bio-compatibility, and tunable photo physical properties. Recently, researchers have focused on hetero atom (N, S and B) doped CNPs due to their excellent properties. These properties make the CNPs and doped CNPs as potential candidates for a wide range of applications. For example, metal ion detection in aqueous solution, bio-imaging, bio-sensing, photovoltaic devices, cleavage of deoxyribonucleic acid (DNA), and catalysis. Therefore, CNPs are alternative to inorganic semiconductor nanoparticles. However, CNPs with diameter less than 10 nm have been prepared using various approaches including top down and bottom methods. Cutting the bulk carbon from high dimensional to zero dimensional by using either physical or chemical process are classified as top down method. Bottom up method refers the conversion of organic precursor to nano-carbon by using thermal pyrolysis, microwave based hydrothermal method, cage opening of C60 molecules. In the present work, I have dealt with the facile synthesis of CNPs and different hetero atom doped carbon nanoparticles (N-CNPs, B-CNPs, and BN-CNPs) using the hydrothermal method. Based on their intriguing physical and chemical properties, these CNPs/doped-CNPs have been explored for various applications such as (i) metal-free catalysts, (ii) color tunability from red to blue and bio-imaging, (iii) ammonia sensing, (iv) white light generation, and (v) detection of picric acid (PA) in aqueous solution. Finally, I have presented 3D nanodendrites of N-CNPs and Pd NPs and their excellent catalytic mass activity for methanol electro-oxidation and ultra-fast reduction of 4-nitrophenol.

Lubricants play an integral role in the operation of several technologies and in biology also, ranging from moving parts in machinery to the biolubrication of artificial joints. We have found that a colloidal dispersion consisting of easily synthesized highly spherical and uniform graphitic carbon particles results in a very efficient water based "green" and environmentally sustainable lubricant with very low friction coefficients and excellent surface wear protection. These particles use a rolling mechanism similar to nano --or microscale ball bearing under confinement. The effect of particle size on lubrication will be introduced and discussed. Additionally, carbon from sugars and carbohydrates, considered as "green precursors" because of their abundance in nature, have been favored for their low environmental impact and cost when compared to traditional oil based lubricants. The second part of my dissertation presents the fabrication and design of a novel bidirectional membrane device to assist child delivery in resource-limited settings. Approximately one third of pregnancies are delivered by one out of three possible operative methods: vacuum extraction, forceps operation, or caesarean section. Using these traditional devices or alternative methods, the risk of injuring to the mother and the fetus is elevated tremendously in the wake of poor training. Here, I present a polymer-based membrane, which will provide ultra-low friction thus facilitating child delivery but also have the ability to provide high friction when needed for child extraction. Specifically, the friction properties between polydimethylsiloxane (PDMS) and a borosilicate surface were studied using different lubricating media. The dynamics of the anisotropic surface morphology will be discussed and applied to this novel membranous device.

Orientadores: Vitor Baranauskas, Leonilda Maria Barbosa dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T15:52:46Z (GMT). No. of bitstreams: 1 Grecco_AnaCarolinaPimenta_M.pdf: 4028722 bytes, checksum: 6c6aa22381786380372d5a804c0a2fe1 (MD5) Previous issue date: 2009 / Resumo: Os nanotubos de carbono estão sob intenso estudo diante da possibilidade de serem utilizados em aplicações biomédicas. Estudos prévios descreveram que a inalação de nanopartículas de carbono induz resposta inflamatória no tecido pulmonar; entretanto o efeito dessas partículas na resposta imune adaptativa não está completamente entendido. Assim, três diferentes preparações de nanotubos de carbono (NT1, NT4, NT5) foram testadas in vivo na resposta de linfócitos T e B de camundongos C57Bl/6. Os nanotubos de paredes múltiplas NT1 e NT4 foram produzidos em nosso laboratório e seu efeito na resposta imune adaptativa foi comparado com uma preparação comercial de nanotubos (NT5). A preparação (NT4) demonstrou alguns efeitos citotóxicos, sendo inadequada para uso in vivo. As outras preparações não mostraram toxicidade quando administradas sistemicamente. Os nanotubos NT1 e NT5 induziram a uma significativa ativação de linfócitos T e B. A administração sistêmica dessas estruturas resultou no aumento da resposta proliferativa de linfócitos ao mitógeno inespecífico Con A, no aumento da expressão de mRNA de citocinas como TNFa, IL-6, IL-10 e significativa redução do TGFß. As nanoestruturas induziram significativo aumento da produção de anticorpos específicos para ovalbumina. Esses resultados enfatizam a importância de estudar a resposta imune induzida pelas nanopartículas antes funcionalizá-las com proteínas, DNA ou utilizá-las na oferta de fármacos. / Abstract: Carbon nanotubes are currently under scrutiny as new tools for biomedical applications. Previous studies have shown that inhalation of carbon nanoparticles elicited an inflammatory response in the lung tissue; however the effect of these particles in the adaptive arm of the immune response deserves more attention. Thus, three different preparations of carbon nanotubes (NT1, NT4, NT5) were tested on in vivo T and B lymphocytes response of C57Bl/6 mice. The multi-walled carbon nanotubes NT1 and NT4 were produced in our facilities and their effect on adaptive immune response was compared to commercial carbon nanotubes (NT5). The preparation (NT4) has demonstrated some cytotoxic effects and was inappropriate for use in vivo. No cytotoxicity was observed in the other preparations when administered systematically in vivo. Carbon nanotubes NT1 and NT5 lead to a significant activation of the T and B lymphocytes. The systemic administration of these structures resulted in increased proliferative response oflymphocytes to nonspecific mitogen ConA, augmented the mRNA cytokines expression such as TNFa, IL-6, IL-10 and significant decrease of TGFß. Nanostructures induced significant increase in the production of antibody to a specific antigen (OVA). These results emphasize the importance of studying the immune response induced by the nanoparticles before functionalizing them with proteins, DNA or for drug delivery purpose. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Les cellules endothéliales cornéennes (CEC) jouent un rôle essentiel pour le maintien de la transparence de la cornée. Cependant, chez l’homme, elles sont incapables de proliférer en raison d’un arrêt de leur cycle cellulaire en phase G1, ce qui rend la couche endothéliale cornéenne particulièrement vulnérable. La délivrance de molécules thérapeutiques (gènes ou médicaments) représente une solution prometteuse pour maintenir la viabilité des CEC. Néanmoins, la difficulté majeure de cette technique repose sur le fait de traverser la membrane cellulaire, normalement imperméable aux molécules de grande taille. Plusieurs techniques de délivrance de molécules ont déjà été testées sur le tissu cornéen mais aucune d’entre elles ne donnent de résultats suffisamment probants pour être utilisée en applications cliniques. L’objectif de cette thèse est d’adapter et de développer une nouvelle technique de délivrance intracellulaire de molécules, basé sur une perforation cellulaire via un phénomène photoacoustique induite par l’activation de nanoparticules de carbone par laser femtoseconde, sur un modèle d’endothélium cornéen in vitro et ex vivo / Corneal endothelial cells (CEC) are essential for corneal transparency. However, on humans, they are unable of proliferation owing to its arrest of G1 phase of the cell cycle, making corneal endothelial monolayer particularly vulnerable. The gene and drug delivery represents a promising solution to maintain CEC viability. Unfortunately, the major difficulty of this technique is the transport across the cell membrane, normally impermeable to high-size molecules. Several techniques of molecules delivery have already been tested on corneal tissue but none of them gives results sufficiently convincing to be used in clinical applications. The aim of this thesis is to adapt and develop a new technique of intracellular molecules delivery, based on cell perforation via photoacoustic effect induced by the activation of carbon nanoparticles by femtosecond laser, on in vitro and ex vivo models of corneal endothelium

The thesis deals with the testing of amyloidogenicity of various carbon nanoparticles and polymers. The first part of the thesis provides the theoretical background of amyloidoses, a group of diseases in which proteins are stored in the insoluble form of amyloid. In addition, the theoretical part also deals with a general overview of nanomaterials and the most important methods. Several types of nanomaterials were tested within the thesis, so the part Results and Discussion was divided into two subchapters: 1) Carbon nanospecies and amyloid fibril formation, and 2) Polysaccharides, glycogen modifications and amyloid fibril formation. The first subchapter concerns the testing of four types of carbon nanoparticles (single-walled carbon nanotubes (SWNT), fullerenes (C60), carbon quantum dots (CDs) and nanodiamonds (NDs)). These materials were tested on a model system hen egg white lysozyme (HEWL). Using fluorescence measurements and transmission electron microscopy (TEM), the nanoparticles were ranked from the most to the least amyloidogenic as follows: NDs> control> C60> CDs> SWNT. The second subchapter deals with the effect of selected polysaccharides (glycogen (GG), mannan (MAN), phytoglycogen (PG)) and modified GG on amyloid fibril formation. These materials were tested on the HEWL model system,...

This Master’s thesis deals with isolating carbon nanoparticles from South Moravian lignite using "green" – environmentally friendly methods. This method consists of mechanical-chemical-thermal stressing of lignite using ultrasound, hydrogen peroxide and high temperatures. This work aims to develop recommendations on coal as a source of carbon nanoparticles and based on these recommendations, to design procedures for isolating nanoparticles from South Moravian lignite using environmentally friendly methods. The identified procedures were designed to meet carbon-based particles with an oxidized surface. From the results we can deduct that it is possible to use South Moravian lignite for the preparation of carbon nanoparticles. However, it will be necessary to modify the process further and also to optimize the purification of the obtained particles.

Materiais auto-organizados constituídos de V2O5 xerogel, poli(etilenoimina) (PEI) e nanopartículas de carbono (NpCs) foram obtidos por meio da técnica camada-por-camada (LbL). A metodologia aplicada permitiu a obtenção de filmes finos com elevado controle de espessura além de permitir um crescimento linear dos filmes, denominados neste trabalho V2O5/PEI e V2O5/PEI/NpCs. Além disso, o desempenho eletroquímico dos materiais auto-organizados foi comparado a um eletrodo de V2O5. Análises de FTIR mostraram que interações específicas entre os grupos amina do PEI e os grupos carboxila do V2O5 são responsáveis pelo crescimento do filme. Estas interações permitem a formação de um campo eletrostático capaz de blindar as interações entre os íons lítio e os oxigênios da vanadila (V=O) e, por consequência, são responsáveis pelo aumento na mobilidade iônica dos íons lítio no interior da matriz hospedeira e, portanto, um aumento na capacidade de armazenamento de carga. Resultados obtidos através de medidas de carga/descarga mostram que o V2O5/PEI/NpCs apresenta uma melhor desempenho do que os demais materiais estudados neste trabalho. Estes resultados mostram que a capacidade específica do V2O5/PEI/NpCs foi de 137 mA h g-1 para a menor densidade de corrente aplicada e aproximadamente 1,6 vezes maior do que os valores de capacidade específica para os outros materiais para a maior densidade de corrente aplicada. Além disso, estas medidas permitiram a observação de uma menor variação na razão estequiométrica máxima (xmáx) em função das densidades de corrente aplicadas para os filmes auto-organizados, fato este relacionado a uma maior mobilidade iônica dos íons lítio no interior dessas matrizes. Os resultados obtidos a partir de espectroscopia de impedância eletroquímica (EIS) mostraram que a difusão dos íons lítio no interior das matrizes auto-organizadas é maior do que no caso do V2O5, cujos valores do coeficiente de difusão foram de 1,64 x 10-15, 1,21 x 10-14 e 2,26 x 10-14 cm2 s-1 para os filmes V2O5, V2O5/PEI e V2O5/PEI/NpCs, respectivamente. Sendo assim, o polímero e as NpCs promoveram novos caminhos condutores e permitiram a conexão elétrica entre camadas isoladas da matriz V2O5. Dessa forma, novos nanocompósitos foram obtidos visando demonstrar o método de auto-organização empregado para melhorar o transporte de carga em matrizes hospedeiras. / Self-assembled materials constituted of V2O5 xerogel, poly (ethyleneimine) (PEI), and carbon nanoparticles (CNPs) were obtained by the layer-by-layer (LbL) technique. The applied methodology permitted the obtainment of thin films with high thickness control and also permitted a linear growth of the films, which will be named V2O5/PEI and V2O5/PEI/CNPs. Besides, the electrochemical performance of the self-assembled materials was compared to a V2O5 electrode. FTIR analyses showed that the specific interactions between the amine groups of PEI and the vanadyl groups of the V2O5 are responsible for the film growth. These interactions permitted the formation of an electrostatic shield capable of hindering the interactions between the lithium ions and the vanadyl oxygen atoms (V=O) and are consequently responsible for the enhancement on the ionic mobility of the lithium ions within the host matrix, leading to a higher energy storage capability. Results obtained by the charge/discharge measurements showed that V2O5/PEI/CNPs presents a better performance than the other materials studied for this research. These results demonstrated that the specific capacity of the V2O5/PEI/CNPs was 137 mA h g-1 under the lowest current density applied and approximately 1.6 times higher than the specific capacity values obtained for the other materials under the highest current density applied. Moreover, it was observed that the variation of the maximum stoichiometric ratio (xmax) as a function of the current density is lower for the self-assembled materials than for the V2O5 electrode, which can be related to the higher ionic mobility of the lithium ion within the self-assembled materials. Electrochemical Impedance Spectroscopy (EIS) data demonstrated that the diffusion of the lithium ions within the self-assembled materials is higher than within the V2O5 electrode, and the diffusion coefficients were 1.64 x 10-15, 1.21 x 10-14 e 2.26 x 10-14 cm2 s-1 for V2O5, V2O5/PEI and V2O5/PEI/CNPs, respectively. Thus, the polymer and the CNPs provided new conducting pathways and connected isolated V2O5 chains in the host matrix. Therefore, novel spontaneous nanocomposites were formed, aiming to demonstrate the self-assembled method adopted for improving charge transport within host matrices.

O aumento no consumo energético e a crescente preocupação ambiental frente à emissão de gases poluentes criam um apelo mundial favorável para pesquisas de novas tecnologias não poluentes de fontes de energia. Baterias recarregáveis de lítio-ar em solventes não aquosos possuem uma alta densidade de energia teórica (5200 Wh kg-1), o que as tornam promissoras para aplicação em dispositivos estacionários e em veículos elétricos. Entretanto, muitos problemas relacionados ao cátodo necessitam ser contornados para permitir a aplicação desta tecnologia, por exemplo, a baixa reversibilidade das reações, baixa potência e instabilidades dos materiais empregados nos eletrodos e dos solventes eletrolíticos. Assim, neste trabalho um modelo cinético foi empregado para os dados experimentais de espectroscopia de impedância eletroquímica, para a obtenção das constantes cinéticas das etapas elementares do mecanismo da reação de redução de oxigênio (RRO), o que permitiu investigar a influência de parâmetros como o tipo e tamanho de partícula do eletrocatalisador, o papel do solvente utilizado na RRO e compreender melhor as reações ocorridas no cátodo dessa bateria. A investigação inicial se deu com a utilização de sistemas menos complexos como uma folha de platina ou eletrodo de carbono vítreo como eletrodos de trabalho em 1,2-dimetoxietano (DME)/perclorato de lítio (LiClO4). A seguir, sistemas complexos com a presença de nanopartículas de carbono favoreceu o processo de adsorção das moléculas de oxigênio e aumentou ligeiramente (uma ordem de magnitude) a etapa de formação de superóxido de lítio (etapa determinante de reação) quando comparada com os eletrodos de platina e carbono vítreo, atribuída à presença dos grupos laterais mediando à transferência eletrônica para as moléculas de oxigênio. No entanto, foi observada uma rápida passivação da superfície eletrocatalítica através da formação de filmes finos de Li2O2 e Li2CO3 aumentando o sobrepotencial da bateria durante a carga (diferença de potencial entre a carga e descarga > 1 V). Adicionalmente, a incorporação das nanopartículas de platina (Ptnp), ao invés da folha de platina, resultou no aumento da constante cinética da etapa determinante da reação em duas ordens de magnitude, o qual pode ser atribuído a uma mudança das propriedades eletrônicas na banda d metálica em função do tamanho nanométrico das partículas, e estas modificações contribuíram para uma melhor eficiência energética quando comparado ao sistema sem a presença de eletrocatalisador. Entretanto, as Ptnp se mostraram não específicas para a RRO, catalisando as reações de degradação do solvente eletrolítico e diminuindo rapidamente a eficiência energética do dispositivo prático, devido ao acúmulo de material no eletrodo. O emprego de líquido iônico como solvente eletrolítico, ao invés de DME, promoveu uma maior estabilização do intermediário superóxido formado na primeira etapa de transferência eletrônica, devido à interação com os cátions do líquido iônico em solução, o qual resultou em um valor de constante cinética da formação do superóxido de três ordens de magnitude maior que o obtido com o mesmo eletrodo de carbono vítreo em DME, além de diminuir as reações de degradação do solvente. Estes fatores podem contribuir para uma maior potência e ciclabilidade da bateria de lítio-ar operando com líquidos iônicos. / The increasing in energetic consumption and environmental concerning toward rising in the emission of pollutant gases create a favorable scenario to develop non-pollutant technologies and more efficient energy storages. Rechargeable non-aqueous lithium-air batteries possess high theoretical energy density (5200 Wh kg-1), characterizing as a promising system to stationary and electric vehicles applications. However, many issues on the cathode electrode should be addressed to enable this technology, for example, low reversibility of the reactions, low rate-capability and instabilities issues from cathode materials and electrolytic solvents. Here, a kinetic model was employed for modulate the experimental impedance data in order to obtain the rate constants of elementary steps from oxygen reduction reaction (ORR), which allows the investigation of the role of some parameters such as, type and grain size of electrocatalysts, and the solvent influence. The initial investigation were with less complexes systems of platinum bulk or glassy carbon as the working electrode in 1,2-dimethoxyethane (DME)/lithium perchlorate (LiClO4). Based on that, the role of carbon nanoparticles in the ORR was an increasing the oxygen adsorption process, and by slightly increasing (one order of magnitude) the superoxide formation (rate determining step) as when compared with platinum and glassy carbon electrodes due to the presence of side groups acting as mediators to the electron transfer. Nonetheless, a fast surface passivation was observed in function of Li2O2 and Li2CO3 thin films formations, and these films increase the battery overpotential during the charge process (potential difference between charge/discharge >1V). In addition, dispersed platinum nanoparticles (Ptnp) resulted in an increase of two orders of magnitude on the rate constant of the rate determining step when compared to platinum bulk. This can be explained due to changes in electronic properties of metallic d-bands in function of nanometric size. These changes contributed to enhance the energetic efficiency of the practical device when compared to the non-catalyzed system. However, the Ptnp were non-specific toward the ORR catalyzing the electrolyte degradation reactions, and decreasing the energy efficiency faster than the non-catalyzed system. The ionic liquid rather than DME promoted better stabilization process for intermediary superoxide due to interaction between cations present in solution, resulting in an outstanding enhancement of the rate constant for rate determining step (three orders of magnitude) when compared to the same working electrode in DME. In addition, decrease the electrolyte degradation reaction. These factors can improve a higher rate-capability and cycle life of the practical lithium-air batteries.