Perovskite nanoparticles for MRI and fluorescence microscopy

of Master diploma thesis Michal Kačenka, Prague 2009 The aim if this thesis is preparation of novel fluorescent magnetic nanoparticles. Such particles are promising materials for biomedical research as dual labeling agents. Silica-coated particles of perovskite phase La0.75Sr0.25MnO3 (LSMO@SiO2) were previously described as a promising material for magnetically induced hyperthermia. Besides, the relaxometric studies of LSMO@SiO2 suspension revealed high values of relaxivity r2, related to the contrast quality in MRI, significantly exceeding that of widely used iron oxide nanoparticles. Binding fluorescent dye into silica layer of LSMO@SiO2 could provide dual probe with the possibility of fluorescence and magnetic resonance detection, suitable for bimodal cellular labeling. The nanoparticles were coated by two-step procedure including the use of mixture of N-1-(3- triethoxysilylpropyl)-N'-fluoresceinylthiourea and tetraethoxysilane in the first step leading to the fluorescent silica shell. The resulting particles exhibit low colloidal stability in water and, therefore, they were subsequently coated by secondary pure silica layer in the next step employing only tetraethoxysilane. The final product exhibits sufficient colloidal stability in water. The morphology and size were investigated by means of..

Perovskite nanoparticles for MRI and fluorescence microscopy

of Master diploma thesis Michal Kačenka, Prague 2009 The aim if this thesis is preparation of novel fluorescent magnetic nanoparticles. Such particles are promising materials for biomedical research as dual labeling agents. Silica-coated particles of perovskite phase La0.75Sr0.25MnO3 (LSMO@SiO2) were previously described as a promising material for magnetically induced hyperthermia. Besides, the relaxometric studies of LSMO@SiO2 suspension revealed high values of relaxivity r2, related to the contrast quality in MRI, significantly exceeding that of widely used iron oxide nanoparticles. Binding fluorescent dye into silica layer of LSMO@SiO2 could provide dual probe with the possibility of fluorescence and magnetic resonance detection, suitable for bimodal cellular labeling. The nanoparticles were coated by two-step procedure including the use of mixture of N-1-(3- triethoxysilylpropyl)-N'-fluoresceinylthiourea and tetraethoxysilane in the first step leading to the fluorescent silica shell. The resulting particles exhibit low colloidal stability in water and, therefore, they were subsequently coated by secondary pure silica layer in the next step employing only tetraethoxysilane. The final product exhibits sufficient colloidal stability in water. The morphology and size were investigated by means of..

Perovskite nanoparticles for MRI and fluorescence microscopy

Department of Inorganic ChemistryKatedra anorganické chemieFaculty of SciencePřírodovědecká fakult

Bimodální makromolekulární kontrastní látky vhodné pro MRI a luminiscenční mikroskopii

Department of Inorganic ChemistryKatedra anorganické chemiePřírodovědecká fakultaFaculty of Scienc

Feromagnetické nanočástice perovskitového typu

Department of Inorganic ChemistryKatedra anorganické chemieFaculty of SciencePřírodovědecká fakult

Fluorescent magnetic nanoparticles for cell labeling: Flux synthesis of manganite particles and novel functionalization of silica shell

International audienceNovel synthetic approaches for the development of multimodal imaging agents with high chemical stability are demonstrated. The magnetic cores are based on La0.63Sr0.37MnO3 manganite prepared as individual grains using a flux method followed by additional thermal treatment in a protective silica shell allowing to enhance their magnetic properties. The cores are then isolated and covered de novo with a hybrid silica layer formed through the hydrolysis and polycondensation of tetraethoxysilane and a fluorescent silane synthesized from rhodamine, piperazine spacer, and 3-iodopropyltrimethoxysilane. The aminoalkyltrialkoxysilanes are strictly avoided and the resulting particles are hydrolytically stable and do not release dye. The high colloidal stability of the material and the long durability of the fluorescence are reinforced by an additional silica layer on the surface of the particles. Structural and magnetic studies of the products using XRD, TEM, and SQUID magnetometry confirm the importance of the thermal treatment and demonstrate that no mechanical treatment is required for the flux-synthesized manganite. Detailed cell viability tests show negligible or very low toxicity at concentrations at which excellent labeling is achieved. Predominant localization of nanoparticles in lysosomes is confirmed by immunofluorescence staining. Relaxometric and biological studies suggest that the functionalized nanoparticles are suitable for imaging applications