In this work, different colloidal gold nanorods were prepared dispersed in different liquid matrices. All gold nanorods were prepared from the acid tethrachloroauric (HAuCl4) in the presence of a reducing agent, using the seed mediated method. The cetyltrimethylammonium bromide (CTAB) was employed as director growth agent. The variable concentration of CTAB in the medium was evaluated in order to verify the selectivity in the formation of nanorods. In addition, we performed a kinetic study to obtain information about the formation mechanism of these particles. Colloid containing gold nanorods in organic matrices such as castor oil and hexafluorophosphate ionic liquid butylmethylilimidazolium (BMIM.PF6) were prepared in order to obtain colloid systems with different physico-chemical characteristics, however among same particles. These new colloids were obtained using the transfer technique of particles, which were synthesized in aqueous medium and then dispersed, after separation, for the desired organic matrix. All colloids were characterized by absorption spectroscopy at ultraviolet and visible (UV-Vis) and nanoparticles characterized by Transmission Electron Microscopy (TEM) / Neste trabalho, diferentes colóides contendo nanobastões de ouro dispersos em diferentes matrizes líquidas foram preparados a partir do ácido tetracloroáurico (HAuCl4), em presença de um agente redutor adequado, através do método mediado por sementes. O brometo de cetiltrimetilamônio (CTAB) foi empregado como agente direcionador de crescimento. A variável concentração de CTAB no meio foi avaliada com o objetivo de verificar a seletividade na formação de nanobastões. Além disso, foi realizado um estudo cinético para obter informações sobre o mecanismo de formação dessas partículas. Coloides contendo nanobastões de ouro em matrizes orgânicas como óleo de mamona e o líquido iônico hexafluorofosfato de butilmetilimidazólio (BMIM.PF6) foram preparados a fim de obter sistemas coloidais com diferentes características fisico-químicas porém com as mesmas partículas. Esses novos colóides foram obtidos através da técnica de transferência de partículas, as quais foram sintetizadas em meio aquoso e posteriormente dispersas, após separação, para a matriz orgânica desejada. Todos os colóides preparados foram caracterizados por Espectroscopia de absorção na região do ultravioleta e visível (UV-Vis) e as nanopartículas caracterizadas por Microscopia na eletrônica de transmissão (MET)

Since the 18th-century scientists are studying diatoms, fascinated by their beauty and diversity. Their nano- and micropatterned biosilica cell walls are outstanding examples of biologically controlled mineral formation. Although the knowledge about diatom cell wall formation increased over the last 60 years, the process is still far away from being completely understood. Diatom cell walls exhibit highly interesting material properties, making them appealing to material scientists. Due to those properties, diatom cell walls are on the brink of becoming powerful tools in nanotechnology. However, the production of tailored silica structures for nanotechnology requires a much better understanding of the processes and components involved in cell wall morphogenesis. Recent studies set the focus on insoluble organic matrices as important parts of this process, suggesting that they act as templates in silica morphogenesis. Therefore, in this study, the occurrence of insoluble organic matrices and their possible silica precipitation activity was analyzed in the three diatom species T. pseudonana, T. oceanica and C. cryptica. For all three species girdle band and valve derived insoluble organic matrices could be identified. The extracted insoluble organic matrices exhibited structural features present in the corresponding biosilica cell walls. The highest similarities were found in the valve derived matrices of C. cryptica. Accessibility studies showed that the biosilica associated insoluble organic matrices of T. pseudonana were only partially accessible, arguing for an entrapment of insoluble organic matrices in the silica, rather than an attachment to the surface of the cell wall. All examined insoluble organic matrices of the three species exhibited intrinsic silica precipitation activity. The most intriguing structures were formed by the insoluble organic matrices of C. cryptica, yielding a porous silica pattern. The addition of biosilica derived soluble components or long-chain polyamines promoted this process and moreover lead to the reconstitution of biosilica-like hierarchical silica pore patterns. The generated silica structures were templated by the underlying structure of the insoluble organic matrix. The result presented in this thesis make this the first study reporting the in vitro generation of diatom biosilica-like hierarchical silica pore patterns using all natural cell wall components. It supports the hypothesis of microplates acting as templates for biosilica morphogenesis and introduces an interesting experimental setup for silica-based in vitro studies on the mechanism of pore formation in diatoms.