Dokument

Summary:
Subject of this cumulative dissertation is the synthesis of nanoparticles and their applications in polymer matrix. Nanoparticles have diameter from 1 to 100 nm. Due to their small size and high surface area these particles show unique optical, magnetic and metallic properties. Because of these properties, nanoparticles exhibit interesting applications in biology, as sensors and electronics fields. There were two main goals of the research work: firstly to synthesize nanoparticles having different properties such as optical, magnetic and metallic, and secondly to embed these nanoparticles in polymer matrix (i.e polyelectrolyte capsules) for biomedical applications such as drug delivery and sensing. The synthesis of nanoparticles was performed in solution in the presence of organic molecules. These molecules so called “surfactant molecules” control the growth of particles during synthesis. For this purpose surfactant molecules bind to and unbind from the surface of growing nanoparticles. These molecules also stabilize the nanoparticles in solution against aggregation and allow one to get particles dispersed in solution; which could be further used in experiments. It was observed that the control of the synthesis parameters could allow one to study the mechanism of particle formation. For very small particles discontinuous growth of nanoparticles was observed where particles were growing from one stable configuration to the next one. In second part of the research work nanoparticles were embedded in polymer matrix. The objective of this was to understand and control the assembly of charged nanoparticles and polymer to form functional polyelectrolyte capsules of micrometer size. Such polyelectrolyte capsules find applications in biomedical for drug delivery and sensing by serving as micro container to store, deliver and/or release cargo materials. Polyelectrolyte capsules were fabricated by so called layer-by-layer (LbL) technique introduced by Decher in 1990s. Using this technique oppositely charged polymers were assembled around a spherical charged template (made of CaCO3) containing the macromolecules. A polymer layers were held together due to their electrostatic interaction, it was possible to introduce charged nanoparticles during the LbL assembly. After the LbL assembly the template was removed to get the polyelectrolyte capsules containing only macromolecules in their cavity. During the research work different nanoparticles were embedded in the walls of the capsules such as fluorescent nanoparticles (e.g QDs), magnetic (e.g FePt & Fe2O3) and metallic nanoparticles (e.g Au). In some experiments walls of capsules were also made fluorescent using organic fluorophores. The cavity of the capsules was filled with different molecules. For sensing applications the cavity of the polyelectrolyte capsules was filled with different ion sensitive fluorophores.

Bibliographie / References

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