Development of silica composite materials aiming at applications in therapy and imaging diagnostic

• Autor(a) principal: Elis Cristina Chagas Gomes
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFC
• Texto Completo: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13374
• topic: SÃlica; FluorescÃncia; Ãxido NÃtrico; Silica; Fluorescence; Nitric Oxide; QUIMICA INORGANICA

In this work nanomaterials based on silica were synthesized aiming their applications in therapy and diagnostic imaging. The study was divided into two parts, the first relating to the synthesis and characterization of modified with folic acid. The second part involves the synthesis and characterization of modified nanoparticles with nitric oxide-releasing complexes. Fluorescent nanoparticles were synthesized from the incorporation of fluorescent dyes in micellar medium containing tetraethylorthosilicate as silica precursor. The materials were functionalized with folic acid and characterized by TEM, nitrogen adsorption isotherms, UV-Vis, FTIR and fluorescence spectroscopy. The data suggest the incorporation of fluorophores to silica matrix with average nanoparticle diameter of 80 nm, low porosity, specific surface Ãrea of 45m2 g-1 and exhibited considerable ability to fluorescent emission. The photophysical studies for nanoparticles containing the two dyes: rhodamine B and dichlorofluorescein indicated the occurrence of Foster resonant energy transfer (FRET) process. The organofunctionalization of the silica matrix was confirmed by FTIR, UV-Vis and fluorescence spectroscopy results, suggesting the immobilization of folic acid to silica matrix by reaction between the amino groups of the composite (NPs-NH2) with the carboxylate groups of the folic acid. In the second part [Fe(CN)4(isn)(NO)]- and cis-[Ru(bpy)2(isn)(NO)]3+ complexes were immobilized on to fluorescent silica nanoparticles All systems synthesized were characterized by UV-vis, FTIR and chronoamperometry (employing a nitric oxide-selective electrode). The characterization data showed the nitric oxide release in the visible region. The composite formed by the iron nitrosyl complex showed more photosensitivity than ruthenium nitrosyl complex. The results of chronoamperometry showed that the fluorescent dye played no key role on the increase of the wavelength of NO release. All systems showed a slow kinetics of NO release which is very promising for controlled release systems.