12 resultados para amido monoéster fosfato
em Universidade do Minho
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Dissertação de mestrado integrado em Engenharia de Materiais
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Tese de Doutoramento em Biologia de Plantas
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Tese de Doutoramento em Ciências - Especialidade em Biologia
Influence of river ecological condition on changes in physico-chemical water parameters along rivers
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Dissertação de mestrado em Ecology
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Dissertação de mestrado em Biologia Molecular, Biotecnologia e Bioempreendedorismo em Plantas
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Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)
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The relaxivity displayed by Gd3+ chelates immobilized onto gold nanoparticles is the result of complex interplay between nanoparticle size, water exchange rate and chelate structure. In this work we study the effect of the length of -thioalkyl linkers, anchoring fast water exchanging Gd3+ chelates onto gold nanoparticles, on the relaxivity of the immobilized chelates. Gold nanoparticles functionalized with Gd3+ chelates of mercaptoundecanoyl and lipoyl amide conjugates of the DO3A-N-(-amino)propionate chelator were prepared and studied as potential CA for MRI. High relaxivities per chelate, of the order of magnitude 28-38 mM-1s-1 (30 MHz, 25 ºC) were attained thanks to simultaneous optimization of the rotational correlation time and of the water exchange rate. Fast local rotational motions of the immobilized chelates around connecting linkers (internal flexibility) still limit the attainable relaxivity. The degree of internal flexibility of the immobilized chelates seems not to be correlated with the length of the connecting linkers. Biodistribution and MRI studies in mice suggest that the in vivo behavior of the gold nanoparticles is determined mainly by size. Small nanoparticles (HD= 3.9 nm) undergo fast renal clearance and avoidance of the RES organs while larger nanoparticles (HD= 4.8 nm) undergo predominantly hepatobiliary excretion. High relaxivities, allied to chelate and nanoparticle stability and fast renal clearance in vivo suggests that functionalized gold nanoparticles hold great potential for further investigation as MRI Contrast Agents. This study contributes to understand the effect of linker length on the relaxivity of gold nanoparticles functionalized with Gd3+ complexes. It is a relevant contribution towards “design rules” for nanostructures functionalized with Gd3+ chelates as Contrast Agents for MRI and multimodal imaging.
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Programa Doutoral em Engenharia Biomédica
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Tese de Doutoramento Programa Doutoral em Engenharia Electrónica e Computadores.
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Dissertação de mestrado em Bioengenharia
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Dissertação de mestrado em Bioengenharia
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Tese de Doutoramento em Biologia Molecular e Ambiental (área de especialização em Biologia Molecular e Saúde).