Doctoral theses
Current Record: 2006 of 2469
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Identifier |
000376813 |
Title |
Σύνθεση και χαρακτηρισμός υβριδικών δομών νανοκρυστάλλων με ρυθμιζόμενες ιδιότητες |
Alternative Title |
Synthesis and characterization of hybrid nanocrystal structures with tailored properties |
Author
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Κωστοπούλου, Αθανασία Ιωάννης
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Thesis advisor
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Λαππας, Αλέξανδρος
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Reviewer
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Τρικαλίτης, Παντελής
Κουτσολέλος, Αθανάσιος
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Abstract |
Considerable progress in the synthesis of colloidal inorganic nanocrystas has allowed their exploitation in different applications, ranging from electronics to biomedicine. A significant advancement in the syntheses of nanocrystals entails the capacity to afford not only single- but multi- material hybrids. This thesis presents the development of colloidal chemistry protocols and the characterization of a self-assembled secondary structure (nanocluster) and a hybrid multimaterial heterostructure.
The nanoclusters involve a low cytotoxivity assembly of small γ-Fe2O3 nanocrystals (NCs). The colloidal assemblies are ferrimagnetic in aqueous dispersions and composed of crystallographically aligned NCs. The colloid of nanoclusters operates as a tunable photonic crystal under a moderate magnetic field. Their potential in biomedical diagnosis (MRI) and therapy (magnetic hyperthermia) is shown. Due to their tailored magneto-structural characteristics, the intra-cluster magnetic material volume fraction is raised, in turn producing a remarkable improvement of the transverse 1H-NMR relaxivity (4-5 times higher than that of the commercial contrast agent Endorem®) and a much higher Specific Loss Power is attained than that of other rival nanostructures.
The hybrid heterostructure consists of ZnO nanorods uniformly covered by size-tunable Fe@FexOy core-shell nanocrystals. The bi-functional [cf. with near band-edge (NBE) UV fluorescence and ferromagnetism at 300 K] nanomaterial is characterized by an extended surface coverage with small Fe@FexOy nanodomains, where the interfacial coupling across the Fe-core and FexOy-shell generates exchange-bias, mediated by frozen interfacial spins. In the case of a lower coverage density by larger Fe@FexOy domains, the operating Kirkendall effect between the core and the shell suppresses the exchange coupling anisotropy. Importantly, the interfacial interactions between ZnO-Fe@FexOy scale with the degree of surface coverage and a strain-induced blue-shift of the NBE is observed.
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Language |
Greek |
Subject |
Colloidal chemistry |
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Contrast agent |
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Core-shell structure |
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Exchange bias |
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Hybrid heterostructure |
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Iron oxide |
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Magnetic hyperthermia |
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Magnetic nanocrystals |
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Magnetic resonance imaging |
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Nanocluster |
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Απεικόνιση μαγνητικού συντονισμού |
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Δομή πυρήνα-κελύφους |
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Κολλοειδής χημεία |
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Μαγνητική υπερθερμία |
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Μαγνητικοί νανοκρύσταλλοι |
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Νανοσυσσωμάτωμα |
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Οξείδιο του σιδήρου |
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Πόλωση λόγω ανταλλαγής |
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Σκιαγραφικό μέσο |
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Υβριδική ετεροδομή |
Issue date |
2012-11-23 |
Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
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Type of Work--Doctoral theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/e/9/metadata-dlib-1353667278-195381-15926.tkl
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Views |
565 |