Nanopartículas (NPs) que apresentam ressonância plasmon de superfície localizada (RPSL) são aplicáveis em diversas áreas como, por exemplo, em terapia e diagnóstico na área biomédica. Estudos e aplicações in vivo requerem que a banda plasmon (BP) ocorra na mesma região da janela terapêutica, entre 600 e 1000 nm. Esta condição pode ser atingida com a modulação da BP pelo controle da morfologia e da composição química das NPs. Os objetivos principais deste trabalho foram estudar métodos de síntese que permitissem obter maiores quantidades de materiais quando comparados aos métodos convencionais em meio aquoso, e conjuntamente avaliar os parâmetros de síntese para obter NPs com diferentes morfologias e composições almejando modular a BP para região de interesse. Obteve-se nanoesferas (NEs) de Au monodispersas com diâmetro médio de 9 nm por redução com oleilamina em solução concentrada de sais de ouro. Dispersibilidade em água com elevada estabilidade coloidal foi alcançada via um procedimento de troca de ligantes, substituindo as moléculas de oleilamina, presentes na superfície das NPs assim como sintetizadas, por moléculas de ácido 11-mecaptoundecanóico. Nanobastões (NBs) de Au (largura de 12 nm) com diferentes comprimentos (30-300 nm) foram obtidos em misturas incomuns das fases cristalinas fcc e hcp. Estes NBs apresentam duas BP no espectro UV-Vis-NIR, uma em 520 nm e outra banda alargada a partir de 800 nm atribuídas à RPSL transversal e longitudinal, respectivamente. Inicialmente, os NBs foram sintetizados utilizando oleilamina como agente redutor e surfactante, sendo posteriormente avaliado que a presença de álcool oleico ou trietilamina no meio mantiveram uma condição de crescimento-1D mantendo a forma dos nanomateriais. NEs de Ag foram obtidas em condições semelhantes às NEs de Au com a BP em torno de 420 nm. Obteve-se misturas de NEs e NBs de AuCu3 (NBs, com razão de aspecto de 3) em todas as condições estudadas, sendo posteriormente separadas. Duas BP foram observadas para os NBs de AuCu3 em 560 e 766 nm, atribuídas à ressonância transversal e longitudinal, respectivamente. NPs monodispersas de Cu1,8S com 10 nm e BP centradas em 1150 nm foram sintetizadas por injeção a quente. Uma tentativa de recobrimento com Au das NPs de Cu1,8S resultou em uma reação de substituição, formando NPs de Au2S, a qual não apresentou BP. Investigou-se sínteses de NPs Cu1,8S dopado com M (M = Fe, Al e Zn) e alguns resultados foram: i) todas amostras foram obtidas na fase digenita e com baixa dispersão de tamanho; ii) Al e Fe incorporaram na estrutura cristalina, mas aparentemente o Zn não incorporou; iii) a BP foi deslocada para maiores comprimentos de ondas em todas amostras. Em resumo, obteve-se NPs com BP na região de interesse, em quantidades maiores que as sínteses convencionais. Este trabalho contribui para a compreensão da ação de reagentes/condições experimentais sobre a composição e o controle morfológico das NPs (principalmente crescimento-1D). Ressalta-se, entre os estudos, a formação de NBs de Au na fase hcp, possibilitando futuros estudos de propriedades; o redshift da BP das NPs de Cu1,8S dopados que não eram esperados, sendo um resultado instigante para futuros estudos; e a efetiva modificação de superfície das NPs de Au que resultou em elevada estabilidade coloidal na faixa de pH entre 6 e 10, possibilitando futuras aplicações. / Nanoparticles (NPs) that present localized surface plasmon resonance (LSPR) enables several applications, for example, therapy and diagnosis in the biomedical area. In vivo studies and applications require that plasmon band occurs in the same region of the therapeutic window, between 600 and 1000 nm. This condition can be achieved with the plasmon band (PB) modulation by morphological and chemical composition control of the NPs. The main purpose of this work concerning to evaluate of the syntheses parameters to obtain NPs with different morphologies and compositions by using experimental procedures, which to enable reach larger NPs amounts than the conventional aqueous medium methods. Monodisperse Au nanospheres (NSs) with average diameter of 9 nm were obtained by reduction of gold salts in concentrated solutions by oleylamine. As-synthesized Au-NSs present oleylamine molecules onto the surface that it was replaced by 11-mercaptoundecanoic acid by using a ligand exchange procedure, resulting in the water-dispersible system with high colloidal stability. Au nanorods (NRs, 12 nm-width) with different lengths (30-300 nm) were synthesized. These NRs are an expressive result, because its present an unusual fcc and hcp crystalline phases mixtures. There is only one paper in the literature that reports the direct synthesis of Au-hcp nanostructure. The NRs dispersion show two PB in the UV-Vis-NIR spectrum at 520 nm and another large band starting in 800 nm attributed to transversal and longitudinal LSPR, respectively. Initially, the NRs were synthetized by using oleylamine as reducing agent and surfactant, and NPs with same shape were obtained in presence of oleyl alcohol or triethylamine as surfactant in the medium. Ag NSs were obtained in similar conditions of Au NSs with shape control, and LSPR band in 420 nm. Mixtures of NSs and NRs (aspect ratio of 3) of AuCu3 were obtained for all studied conditions, and separated by using a selective separation process. Two PB were observed for AuCu3 NRs at 560 and 766 nm, assigned to transversal and longitudinal resonance, respectively. Monodisperse Cu1,8S semiconductor NSs with 10 nm and PB centered in 1150 nm were synthetized via hot-injection, and attempts to cover them with Au resulted in a substitution reaction that lead the formation of Au2S NPs, which did not present PB. Syntheses of M-doped Cu1,8S NPs (M = Fe, Al e Zn) were investigated and some results were: i) all samples are digenite phase and presented low dispersivity of size; ii) Al and Fe were incorporate more effective into the crystal structure than Zn; iii) were observed redshift of PB for all samples. In summary, NPs with PB in the region of interest were obtained in greater amounts than the conventional syntheses. This thesis presents contributions to the understanding of experimental parameters that act on the compositional and morphological control of NPs (mainly 1D growth). It is emphasized among the studies: the formation of Au NRs in the hcp phase, enabling future studies of properties; the PB redshift of the doped Cu1,8S NPs that were not expected, however, this is a stimulating result for future studies; and an effective surface modification of the Au NPs that result in high colloidal stability in the pH range between 6 and 10, allowing for future applications.

Nanopartículas (NPs) que apresentam ressonância plasmon de superfície localizada (RPSL) são aplicáveis em diversas áreas como, por exemplo, em terapia e diagnóstico na área biomédica. Estudos e aplicações in vivo requerem que a banda plasmon (BP) ocorra na mesma região da janela terapêutica, entre 600 e 1000 nm. Esta condição pode ser atingida com a modulação da BP pelo controle da morfologia e da composição química das NPs. Os objetivos principais deste trabalho foram estudar métodos de síntese que permitissem obter maiores quantidades de materiais quando comparados aos métodos convencionais em meio aquoso, e conjuntamente avaliar os parâmetros de síntese para obter NPs com diferentes morfologias e composições almejando modular a BP para região de interesse. Obteve-se nanoesferas (NEs) de Au monodispersas com diâmetro médio de 9 nm por redução com oleilamina em solução concentrada de sais de ouro. Dispersibilidade em água com elevada estabilidade coloidal foi alcançada via um procedimento de troca de ligantes, substituindo as moléculas de oleilamina, presentes na superfície das NPs assim como sintetizadas, por moléculas de ácido 11-mecaptoundecanóico. Nanobastões (NBs) de Au (largura de 12 nm) com diferentes comprimentos (30-300 nm) foram obtidos em misturas incomuns das fases cristalinas fcc e hcp. Estes NBs apresentam duas BP no espectro UV-Vis-NIR, uma em 520 nm e outra banda alargada a partir de 800 nm atribuídas à RPSL transversal e longitudinal, respectivamente. Inicialmente, os NBs foram sintetizados utilizando oleilamina como agente redutor e surfactante, sendo posteriormente avaliado que a presença de álcool oleico ou trietilamina no meio mantiveram uma condição de crescimento-1D mantendo a forma dos nanomateriais. NEs de Ag foram obtidas em condições semelhantes às NEs de Au com a BP em torno de 420 nm. Obteve-se misturas de NEs e NBs de AuCu3 (NBs, com razão de aspecto de 3) em todas as condições estudadas, sendo posteriormente separadas. Duas BP foram observadas para os NBs de AuCu3 em 560 e 766 nm, atribuídas à ressonância transversal e longitudinal, respectivamente. NPs monodispersas de Cu1,8S com 10 nm e BP centradas em 1150 nm foram sintetizadas por injeção a quente. Uma tentativa de recobrimento com Au das NPs de Cu1,8S resultou em uma reação de substituição, formando NPs de Au2S, a qual não apresentou BP. Investigou-se sínteses de NPs Cu1,8S dopado com M (M = Fe, Al e Zn) e alguns resultados foram: i) todas amostras foram obtidas na fase digenita e com baixa dispersão de tamanho; ii) Al e Fe incorporaram na estrutura cristalina, mas aparentemente o Zn não incorporou; iii) a BP foi deslocada para maiores comprimentos de ondas em todas amostras. Em resumo, obteve-se NPs com BP na região de interesse, em quantidades maiores que as sínteses convencionais. Este trabalho contribui para a compreensão da ação de reagentes/condições experimentais sobre a composição e o controle morfológico das NPs (principalmente crescimento-1D). Ressalta-se, entre os estudos, a formação de NBs de Au na fase hcp, possibilitando futuros estudos de propriedades; o redshift da BP das NPs de Cu1,8S dopados que não eram esperados, sendo um resultado instigante para futuros estudos; e a efetiva modificação de superfície das NPs de Au que resultou em elevada estabilidade coloidal na faixa de pH entre 6 e 10, possibilitando futuras aplicações. / Nanoparticles (NPs) that present localized surface plasmon resonance (LSPR) enables several applications, for example, therapy and diagnosis in the biomedical area. In vivo studies and applications require that plasmon band occurs in the same region of the therapeutic window, between 600 and 1000 nm. This condition can be achieved with the plasmon band (PB) modulation by morphological and chemical composition control of the NPs. The main purpose of this work concerning to evaluate of the syntheses parameters to obtain NPs with different morphologies and compositions by using experimental procedures, which to enable reach larger NPs amounts than the conventional aqueous medium methods. Monodisperse Au nanospheres (NSs) with average diameter of 9 nm were obtained by reduction of gold salts in concentrated solutions by oleylamine. As-synthesized Au-NSs present oleylamine molecules onto the surface that it was replaced by 11-mercaptoundecanoic acid by using a ligand exchange procedure, resulting in the water-dispersible system with high colloidal stability. Au nanorods (NRs, 12 nm-width) with different lengths (30-300 nm) were synthesized. These NRs are an expressive result, because its present an unusual fcc and hcp crystalline phases mixtures. There is only one paper in the literature that reports the direct synthesis of Au-hcp nanostructure. The NRs dispersion show two PB in the UV-Vis-NIR spectrum at 520 nm and another large band starting in 800 nm attributed to transversal and longitudinal LSPR, respectively. Initially, the NRs were synthetized by using oleylamine as reducing agent and surfactant, and NPs with same shape were obtained in presence of oleyl alcohol or triethylamine as surfactant in the medium. Ag NSs were obtained in similar conditions of Au NSs with shape control, and LSPR band in 420 nm. Mixtures of NSs and NRs (aspect ratio of 3) of AuCu3 were obtained for all studied conditions, and separated by using a selective separation process. Two PB were observed for AuCu3 NRs at 560 and 766 nm, assigned to transversal and longitudinal resonance, respectively. Monodisperse Cu1,8S semiconductor NSs with 10 nm and PB centered in 1150 nm were synthetized via hot-injection, and attempts to cover them with Au resulted in a substitution reaction that lead the formation of Au2S NPs, which did not present PB. Syntheses of M-doped Cu1,8S NPs (M = Fe, Al e Zn) were investigated and some results were: i) all samples are digenite phase and presented low dispersivity of size; ii) Al and Fe were incorporate more effective into the crystal structure than Zn; iii) were observed redshift of PB for all samples. In summary, NPs with PB in the region of interest were obtained in greater amounts than the conventional syntheses. This thesis presents contributions to the understanding of experimental parameters that act on the compositional and morphological control of NPs (mainly 1D growth). It is emphasized among the studies: the formation of Au NRs in the hcp phase, enabling future studies of properties; the PB redshift of the doped Cu1,8S NPs that were not expected, however, this is a stimulating result for future studies; and an effective surface modification of the Au NPs that result in high colloidal stability in the pH range between 6 and 10, allowing for future applications.

Recent advancements in nanotechnology and emerging applications of nanomaterials in various fields have stimulated interest in fundamental scientific research dealing with the size and structure controlled synthesis of nanoparticles. The unique properties of nanoparticles are largely size dependent which could be tuned further by varying shape, structure, and surface properties, etc. The preparation of monodisperse nanoparticles is desirable for many applications due to better control over properties and higher performance compared to polydispersity nanoparticles. There are several methods for the synthesis of nanoparticles based on top-down and bottom-up approaches. The main disadvantage of top-down approach is the difficulty in achieving size control. Whereas, uniform nanoparticles with controllable size could be obtained by chemical methods but most of them are difficult to scale up. Moreover, a separate step of size separation is necessary in order to achieve monodispersed which may lead to material loss. In this context, a post-synthetic size modification process known as digestive ripening is highly significant. In this process, addition of a capping agent to poly disperse colloid renders it highly monodisperse either under ambient or thermal conditions. In addition to size control, digestive ripening is also effective in controlling the structure of nanoparticles in colloidal solution comprising two different elements. Use of co-digestive ripening strategy in conjunction with solvated metal atom dispersion (SMAD) method of synthesis resulted in hetero structures such as core–shell, alloy, and composite nanoparticles. Despite the versatility of digestive ripening process, the underlying mechanism in controlling size and structure of nanoparticles are not understood to date. The aim of this thesis is to gain mechanistic insight into size control of digestive ripening as well as to investigate structure control in various binary systems. Objectives  Study digestive ripening of Au nanoparticles using various alkyl amines to probe the mechanism  Study co-digestive ripening of binary colloids consisting of two metals, Pd and Cu prepared separately by SMAD method  Study co-digestive ripening of binary colloids consisting of a metal (Au) and a semiconductor (CdS) prepared separately by SMAD method  Study vaporization of bulk brass in SMAD reactor and analyse phase, structure, and morphology of various Cu/Zn bimetallic nanoparticles obtained from bulk brass under various experimental conditions Significant results In chapter 1, fundamental processes of nanoparticle formation and common synthetic techniques for the preparation of monodisperse nanoparticles are briefly discussed. Chapter 2 presents a mechanistic study of digestive ripening process with regard to size control using Au nanoparticles as a model system. Three long chain alkyl amine molecules having different chain length were used as digestive ripening agents. The course of digestive ripening process was analysed by UV-visible spectroscopy and transmission electron microscopy. The experimental conditions such as concentration of digestive ripening agent, time, and temperature were found to influence the size distribution of nanoparticles. The average particle size was found to be characteristic of metal-digestive ripening agent combination which is considered as the optimum size preferred during digestive ripening under a given set of experimental conditions. This study discusses stabilization of optimum sized particles, surface etching, and reversibility in digestive ripening. Chapter 3 describes the synthesis and characterization of PdCu alloy nanoparticles by co-digestive ripening method. Syntheses of individual Pd and Cu colloids were carried out by SMAD method. Pd nanoparticles obtained using THF as solvent and in the absence of any capping agent resulted in an extended small Pd nanowire network assembly. Morphological evolution of spherical Pd nanoparticles from Pd nanowire network structure was observed with the use of capping agent, hexadecyl amine (HDA) in SMAD method. Co-digestive ripening of Pd and Cu colloids was studied at various temperatures. This study revealed temperature dependent diffusion of Cu atoms into Pd lattice forming PdCu alloy nanoparticles. Next, co-digestive ripening of a colloidal system comprising a metal and a semiconductor was explored. Au-CdS combination was chosen for this study owing to its interesting photocatalytic properties. Chapter 4 deals with the synthesis of Au and CdS nanoparticles by SMAD method and Au/CdS nanocomposite by co-digestive ripening. CdS nanoparticles of size 4.0 + 1.2 nm and Au nanoparticles of size 5.6 + 1.1 nm were obtained as a result of digestive ripening process. Au/CdS nanocomposite obtained by co-digestive ripening was characterized by a matrix-like structure made up of CdS nanoparticles in which Au nanoparticles were embedded. CdS nanoparticles were found to establish an intimate surface contact with Au nanoparticles and the matrix of CdS surrounding Au was developed via aggregation during digestive ripening. Chapter 5 describes a comprehensive study on various Cu/Zn bimetallic nanoparticles obtained from bulk brass. Vaporization of bulk brass in SMAD reactor led to a deploying process and further growth of nanoparticles from phase separated Cu and Zn atoms formed a composite structure. The characterization of Cu/Zn nanocomposite revealed covering of composite surface with Cu resulting in a core-shell structure, Cu/Zn@Cu. Post-synthetic digestive ripening of these core-shell composite particles showed diffusion of Zn atoms to the composite surface in addition to size and shape modification. Annealing of Cu/Zn nanocomposites prepared in THF resulted in α-CuZn alloy nanoparticles via sequential transformation through η-CuZn5, γ-Cu5Zn8, and β-CuZn (observed as marten site) phases.