Insertion of inorganic nanoparticles inside onion-type multilamellar lipidic vesicles

Ce travail de thèse a porté sur l'incorporation de nanoparticules inorganiques au sein de vésicules multilamellaires lipidiques de type " oignon ". La synthèse intravésiculaire de nanoparticules d'or a été réalisée par voie chimique, photoréduction UV et radiolyse gamma. Nous avons montré qu'il est possible de contrôler la morphologie des particules par la composition vésiculaire dans le cas d'une réduction chimique. Quelle que soit la voie de synthèse, nous avons établi que la stabilité de l'oignon dépend de la taille des nanoparticules qu'il contient et de leur nombre. L'utilisation de ces structures hybrides,oignons/nanoparticules (or et argent), pour la catalyse supportée a été abordée. Nous avons également élaboré des oignons magnétiques selon deux voies: par synthèse intravésiculaire de nanoparticules magnétiques et par encapsulation d'un ferrofluide. Les propriétés des oignons en terme de magnétisme, d'hyperthermie magnétique et d'agents de contraste pour IRM ont été étudiées.This work deals with the insertion of inorganic nanoparticles inside onion-type multilamellar vesicles. Intravesicular synthesis of gold nanoparticles was performed via three paths: chemical reduction, UV photoreduction and gamma radiolysis. Control of nanoparticles morphology via chemical composition of vesicles was demonstrated for chemical reduction. Whatever the synthetic path, onion stability depends on the number and the size of synthesized particles. Such an organic/inorganic hybrid, onion/nanoparticles (gold and silver), was tested for heterogeneous catalysis. Magnetic onions were also elaborated via two methods: intravesicular synthesis of magnetic nanoparticles and ferrofluid encapsulation. Magnetic properties of onions, as contrast agent for MRI and for hyperthermia, were measured

Incorporation de nanoparticules inorganiques dans des vésicules multilamellaires lipidiques de type " oignon "

This work deals with the insertion of inorganic nanoparticles inside onion-type multilamellar vesicles. Intravesicular synthesis of gold nanoparticles was performed via three paths: chemical reduction, UV photoreduction and gamma radiolysis. Control of nanoparticles morphology via chemical composition of vesicles was demonstrated for chemical reduction. Whatever the synthetic path, onion stability depends on the number and the size of synthesized particles. Such an organic/inorganic hybrid, onion/nanoparticles (gold and silver), was tested for heterogeneous catalysis. Magnetic onions were also elaborated via two methods: intravesicular synthesis of magnetic nanoparticles and ferrofluid encapsulation. Magnetic properties of onions, as contrast agent for MRI and for hyperthermia, were measured.Ce travail de thèse a porté sur l'incorporation de nanoparticules inorganiques au sein de vésicules multilamellaires lipidiques de type " oignon ". La synthèse intravésiculaire de nanoparticules d'or a été réalisée par voie chimique, photoréduction UV et radiolyse gamma. Nous avons montré qu'il est possible de contrôler la morphologie des particules par la composition vésiculaire dans le cas d'une réduction chimique. Quelle que soit la voie de synthèse, nous avons établi que la stabilité de l'oignon dépend de la taille des nanoparticules qu'il contient et de leur nombre. L'utilisation de ces structures hybrides,oignons/nanoparticules (or et argent), pour la catalyse supportée a été abordée. Nous avons également élaboré des oignons magnétiques selon deux voies: par synthèse intravésiculaire de nanoparticules magnétiques et par encapsulation d'un ferrofluide. Les propriétés des oignons en terme de magnétisme, d'hyperthermie magnétique et d'agents de contraste pour IRM ont été étudiées

Incorporation de nanoparticules inorganiques dans des vésicules multilamellaires lipidiques de type "oignon"

Ce travail de thèse a porté sur l'incorporation de nanoparticules inorganiques au sein de vésicules multilamellaires lipidiques de type "oignon" La synthèse intravésiculaire de nanoparticules d'or a été réalisée par voie chimique, photoréduction UV et radiolyse gamma. Nous avons montré qu'il est possible de contrôler la morphologie des particules par la composition vésiculaire dans le cas d'une réduction chimique. Quelle que soit la voie de synthèse, nous avons établi que la stabilité de l'oignon dépend de la taille des nanoparticules qu'il contient et de leur nombre. L'utilisation de ces structures hybrides, oignons/nanoparticules (or et argent), pour la catalyse supportée a été abordée. Nous avons également élaboré des oignons magnétiques selon deux voies : par synthèse intravésiculaire de nanoparticules magnétiques et par encapsulation d'un ferrofluide. Les propriétés des oignons en terme de magnétisme, d'hyperthermie magnétique et d'agents de contraste pour IRM ont été étudiées.BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Radiation-induced synthesis of gold nanoparticles within lamellar Phases. Formation of aligned colloidal gold by radiolysis

A sheared lamellar phase has been used as a nanoreactor for the synthesis of gold nanoparticles by radiolysis and by a photochemical approach. A gold salt solution (KAuCl4, 10-2 M) is introduced into the aqueous compartments between the lipid-based bilayers. Gold nanoparticles grow within the lamellar phase as shown by TEM analysis and X-ray diffraction, limiting the particle size. Homodisperse, 2.4- and 5.9-nm-sized, spherical nanoparticles are produced by irradiation and UV irradiation, respectively. When produced by radiolysis, they are perfectly aligned along the lamellae. Their UV-vis spectra display a maximum at 565 nm suggesting that nanoparticles are coupled by dipole-dipole interactions within the lamellar phase

Synthesis of stable, gold-particle-containing onion-type multilamellar vesicles. Influence of particle size on the onions' internal

In a previous paper, we reported that large gold particles (about 100 nm) could be synthesized in onion-type multilamellar vesicles, but with consecutive onion destruction (Regev et al 2004 Chem. Mater. 16 5280). Here, we modified the experimental synthesis process to produce stable phosphatidylcholine- (PC-) based onions containing 3–10 nm size gold particles. Direct hydration of the sheared lamellar phase with a 10−2 M KAuCl4 solution was used. Insertion of octadecylamine into PC–monoolein onion bilayers results in a decrease of gold particle size from 45 nm down to 5 nm. A reduction process is proposed, which notably enlightens gold formation kinetics. Monoolein is shown to act as the chemical reductant by FT-IR analysis, while a photon-induced reduction is assumed for bilayers depleted in monoolein. The effect of gold particles on lamellar arrangement is tackled by small angle x-ray diffraction experiments, while the stability of particle-containing onion-type multilamellar vesicles is discussed using cryo-TEM imaging

Magnetic Multilamellar Liposomes Produced by In Situ Synthesis of Iron Oxide Nanoparticles: "Magnetonions"

We report the formation of magnetic onion-type multilamellar vesicles. Iron oxide nanoparticles (np's) were synthesized inside lipidic multilamellar vesicles by coprecipitation of vesicle-encapsulated Fe2+ and Fe3+ ions induced by HO- diffusion through vesicle lamellae. The iron ion encapsulation efficiency of onions was measured by potentiometry and UV-vis absorbance spectroscopy. Its high value (75 ( 5% for both Fe2+ and Fe3+) ensures an intravesicular synthesis, as confirmed by cryo-transmission electron microscopy (TEM) imaging. The as-grown nanoparticles are characterized by X-ray diffraction analysis and TEM, and magnetic onions are imaged by cryo-TEM. The np size, controlled by temperature and time, ranges from 3 to 6 nm and is shown to be a key parameter for onion stability

Production of magnetic multilamellar liposomes as highly T(2)-efficient MRI contrast agents.

Lipid-based multilamellar vesicles loaded with aminosilane-modified maghemite nanoparticles (a-MNPs), also called magnetonions (MO), were analyzed for their magnetic resonance imaging (MRI) contrast agent properties. They were shown to be better T(2)-MRI contrast agents than commercial contrast agents and other reported liposome-based contrast agents as shown by their higher value of relaxivity ratio (r(2)/r(1) = 17), although a lower magnetic field intensity was used (0.2 T). Their high efficiency was explained by the aggregation of a-MNPs in between multilamellar vesicles, bilayers induced by MO preparation, and evidenced by cryo-TEM imaging. Magnetonions are then a promising platform for diagnosis and therapy. FROM THE CLINICAL EDITOR: In this study, magnetonions (MO) are presented as a very potent T2 relaxation enhancing MRI contrast agents. Such agents may be used in cell labeling and molecular imaging applications

Onion-type multilamellar vesicles as an innovative tool for the preparation of metal-based heterogeneous catalysts

A new route for the preparation of metal-based catalysts has thus been investigated. Onion-grown silver and gold nanoparticles have been deposited onto a TiO2 support. As micro reactors for the synthesis of the metal nanoparticles, onions offer the possibility to control the size and shape of the nanoparticles. As previously evidenced the synthesis is spontaneous and doesn’t require any addition of a strong reducing agent. The catalyst support is “decorated” through the direct impregnation of the loaded onions. No further thermal treatment is required to obtain the active metal nanoparticles

Production of magnetic multilamellar liposomes as highly T(2)-efficient MRI contrast agents.

Lipid-based multilamellar vesicles loaded with aminosilane-modified maghemite nanoparticles (a-MNPs), also called magnetonions (MO), were analyzed for their magnetic resonance imaging (MRI) contrast agent properties. They were shown to be better T(2)-MRI contrast agents than commercial contrast agents and other reported liposome-based contrast agents as shown by their higher value of relaxivity ratio (r(2)/r(1) = 17), although a lower magnetic field intensity was used (0.2 T). Their high efficiency was explained by the aggregation of a-MNPs in between multilamellar vesicles, bilayers induced by MO preparation, and evidenced by cryo-TEM imaging. Magnetonions are then a promising platform for diagnosis and therapy. FROM THE CLINICAL EDITOR: In this study, magnetonions (MO) are presented as a very potent T2 relaxation enhancing MRI contrast agents. Such agents may be used in cell labeling and molecular imaging applications

Onion-like vesicles as bio-inspired microreactors for the preparation of metal-based inorganic catalysts

With a new “bio-inspired” concept merging the expertise in biotechnology and heterogeneous catalysis we were able to produce metal based heterogeneous catalysts with small and stable nanoparticles