Human ceruloplasmin and neurotransmitters: complex stabilization and crystallization

Dissertation to obtain a Master Degree in Molecular Genetics and Biomedicine at Faculty of Sciences and Technology,Universidade Nova de Lisboa

Fluorescence in nanostructured fulleride films

Applied Physics Letters, 89

Dynamic and interaction of cytochrome c with Pf1 virus

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em BioOrgânica

Printed electronics for ubiquitous computing applications

Dissertação para obtenção do Grau de Doutor em Química

Role of surfactants in filtration and fouling of colloidal silica

The EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centres and universities

Synthesis of Polymeric Nanoparticles for biomedical delivery applications

Polymeric nanoparticles (PNPs) have attracted considerable interest over the last few years due to their unique properties and behaviors provided by their small size. Such materials could be used in a wide range of applications such as diagnostics and drug delivery. Advantages of PNPs include controlled release, protection of drug molecules and its specific targeting, with concomitant increasing of the therapeutic index. In this work, novel sucrose and cholic acid based PNPs were prepared from different polymers, namely polyethylene glycol (PEG), poly(D,L-lactic-co-glycolic acid) (PLGA) and PLGA-co-PEG copolymer. In these PNP carriers, cholic acid will act as a drug incorporation site and the carbohydrate as targeting moiety. The uptake of nanoparticles into cells usually involves endocytotic processes, which depend primarily on their size and surface characteristics. These properties can be tuned by the nanoparticle preparation method. Therefore, the nanoprecipitation and the emulsion-solvent evaporation method were applied to prepare the PNPs. The influence of various parameters, such as concentration of the starting solution, evaporation method and solvent properties on the nanoparticle size, size distribution and morphology were studied. The PNPs were characterized by using atomic force microscopy (AFM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) to assess their size distribution and morphology. The PNPs obtained by nanoprecipitation ranged in size between 90 nm and 130 nm with a very low polydispersity index (PDI < 0.3). On the other hand, the PNPs produced by the emulsion-solvent evaporation method revealed particle sizes around 300 nm with a high PDI value. More detailed information was found in AFM and SEM images, which demonstrated that all these PNPs were regularly spherical. ζ-potential measurements were satisfactory and evidenced the importance of sucrose moiety on the polymeric system, which was responsible for the obtained negative surface charge, providing colloidal stability. The results of this study show that sucrose and cholic acid based polymeric conjugates can be successfully used to prepare PNPs with tunable physicochemical characteristics. In addition, it provides novel information about the materials used and the methods applied. It is hoped that this work will be useful for the development of novel carbohydrate based nanoparticles for biomedical applications, specifically for targeted drug delivery.

Nanocomposite polymer beads for cell detection

Circulating tumor cells (CTCs) may induce metastases when detached from the primary tumor. The numbers of these cells in blood offers a valuable prognostic indication. Magnetoresistive sensing is an attractive option for CTC counting. In this technique, cells are labeled with nancomposite polymer beads that provide the magnetic signal. Bead properties such as size and magnetic content must be optimized in order to be used as a detection tool in a magnetoresistive platform. Another important component of the platform is the magnet required for proper sensing. Both components are addressed in this work. Nanocomposite polymer beads were produced by nano-emulsion and membrane emulsification. Formulations of the oil phase comprising a mixture of aromatic monomers and iron oxide were employed. The effect of emulsifier (surfactant) concentration on bead size was studied. Formulations of polydimethilsiloxane (PDMS) with different viscosities were also prepared with nano-emulsion method resulting in colloidal beads. Polycaprolactone (PCL) beads were also synthetized by the membrane emulsification method. The beads were characterized by different techiques such as dynamic light scattering (DLS), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Additionally, the magnet dimensions of the platform designed to detect CTCs were optimized through a COMSOL multiphysics simulation.

Solution processed quantum dot photodetectors

To find sustainable solutions for the production of energy, it is necessary to create photovoltaic technologies that make every photon count. To pursue this necessity, in the present work photodetectors of zinc oxide embedded with nano-structured materials, that significantly raise the conversion of solar energy to electric energy, were developed. The novelty of this work is on the development of processing methodologies in which all steps are in solution: quantum dots synthesis, passivation of their surface and sol-gel deposition. The quantum dot solutions with different capping agents were characterized by UVvisible absorption spectroscopy, spectrofluorimetry, dynamic light scattering and transmission electron microscopy. The obtained quantum dots have dimensions between 2 and 3nm. These particles were suspended in zinc acetate solutions and used to produce doped zinc oxide films with embedded quantum dots, whose electric response was tested. The produced nano-structured zinc oxide materials have a superior performance than the bulk, in terms of the produced photo-current. This indicates that an intermediate band material should have been produced that acts as a photovoltaic medium for solar cells. The results are currently being compiled in a scientific article, that is being prepared for possible submission to Energy and Environmental Science or Nanoscale journals.