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Title: Mixed-monolayer protected gold nanoparticles for applications in medicine
Authors: Bidoggia, Silvia
Keywords: self-assemblyphase segregationmulticale molecular simulationssupramolecular chemistryfluorinated compounds
Issue Date: 9-Apr-2013
Publisher: Università degli studi di Trieste
Abstract: In the last years, gold nanoparticles (AuNPs) protected by an organic shell of ligands have received a large interest for applications in the biomedical field in particular for diagnosis, imaging and therapy. This class of nanomaterials is largely used because of the easy of synthesis with different core sizes and shapes and controlled dispersion. Moreover, NPs can be protected by a large variety of organic compounds, with different functionalities and to allow the linkage of drugs and biomolecules. The nature of the ligand is responsible of the solubility of the NPs and could be also tuned in order to have NPs soluble in water and in the biological environment. Additionally, at least gold is no toxic, biocompatible and could be easily released from the body. The present thesis is focused on three projects. The first one deals with the study of the morphology of gold nanoparticles coated by a mixture of hydrogenated and fluorinated ligands which solubility in water is favored by the presence of PEG chains. Few years ago, our research group has shown that mixtures of these hydrogenated and fluorinated ligands, forming the monolayer of gold nanoparticles, phase-segregate in separated domains because of the reciprocal immiscibility of the two chains. During this thesis, we wanted to investigate more deeply the organization of such monolayers and in particular, to understand the shape and the size of these domains. In collaboration with the group of Prof. S. Pricl and Prof. M. Fermeglia of the University of Trieste, in silico experiments have been performed in order to predict the size and the shape of these domains. Moreover, we have studied how the shape and the size of these domains is influenced by the ratio between the two thiols, the size of the core and the difference in length between the two ligands. The obtained results were supported by further ESR experiments performed by Prof. Lucarini of the University of Bologna. ESR experiments have allowed us to estimate the value of the affinity constants of the probe for the fluorinated and hydrogenated domains of the monolayer and to establish that mixed monolayers have chemical and physical properties that cannot be predicted by simply knowing the properties of homoligand monolayers. The results that have been reported in a recent publication on ACS Nano are presented in Chapter 3. The second project of this PhD thesis is based on the synthesis and characterization of water soluble gold nanoparticles coated by different ratios of charged hydrogenated ligands and commercially available fluorinated ligands. Some of these nanoparticles, with an average core diameter between 3 and 4 nm, have been used for preliminary investigations in vitro. In particular, cell membrane permeation and the cellular toxicity have been evaluated. These experiments have been performed in collaboration with the group of Prof. Stellacci in IFOM-IEO, Milan. Preliminary results are described in Chapter 4. The last part of this PhD project is focused on the synthesis and characterization of NPs coated by mixtures of commercially available fluorinated and hydrogenated thiols. These NPs present the advantages over those described in Chapter 3 and Chapter 4 because they are suited for a direct “visualization” by STM experiments and may help us in understanding the rules governing the organization of mixtures of fluorinated and hydrogenated ligands on a curved surface. The choice to synthesize NPs without charged groups is dictated by the limitations of STM technique. In Chapter 5 synthetic aspects and preliminary STM results would be presented.
Description: 2011/2012
NBN: urn:nbn:it:units-9978
Appears in Collections:Scienze chimiche

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