Estudo, caracterização e propriedades de ortofosfatos multifuncionais
- Autores: Thales Rafael Machado
- Directores de la Tesis: Héctor Beltrán Mir (dir. tes.), Elson Longo da Silva (dir. tes.), Eloisa Cordoncillo Cordoncillo (dir. tes.)
- Lectura: En la Universitat Jaume I ( España ) en 2016
- Idioma: portugués
- Número de páginas: 223
- Títulos paralelos:
- Estudio, caracterización y propiedades e ortofosfatos multifuncionales
- Tribunal Calificador de la Tesis: Elson Longo da Silva (presid.), Natalia Mayumi Inada (secret.), Ieda Lucia Viana Rosa (voc.), Lucia Helena Mascaro Sales (voc.), Máximo Siu Li (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
- español
La investigación científica en materiales inorgánicos atóxicos con propiedades fotoluminiscentes (FL) tiene sido intensificada para aplicaciones biomédicas. Esta tesis doctoral tiene como objetivo el estudio de las propiedades ópticas de la hidroxiapatita [HA, Ca10(PO4)6(OH)2] y sus correlaciones con las propiedades estructurales, composicionales y morfológicas. Además, se presenta un estudio preliminar con la evaluación de biocompatibilidad, capacidad de internalización y marcación celular por la FL. Las muestras de HA fueron sintetizadas por precipitación química a 90 ºC en un medio básico (pH ~10) y ácido (pH ~5). La velocidad de adición de los precursores fue variada en cada grupo (600, 7 o 1,5 mL/min). Se estudiaran los efectos de los posteriores tratamientos térmicos en temperaturas de 200-800 ºC en las propiedades de la HA pura, y a 600 ºC y 1100 ºC con una etapa de enfriamiento normal, bien como al efectuar enfriamiento rápido en N2 líquido para las muestras HAEu.
- English
Scientific research focused on non-toxic inorganic materials with photoluminescence (PL) properties has been intensified in pursuance of biomedical applications. Considering this purpose, hydroxyapatite [HA, Ca10(PO4)6(OH)2] present low toxicity and a crystalline structure which can stabilize distinct luminescent centres based on structural defects, and lanthanides (Eu3+, Tb3+, Gd3+, etc.). This thesis aims to contribute with the study of the optical properties of pure and Eu3+-doped HA (HAEu) and their correlation to its structural, compositional and morphological properties. Moreover, a preliminary study comprising of biocompatibility evaluation, internalization capability and cell labelling by PL is presented. The HA samples were synthesized by chemical precipitation at 90 ºC in a basic (pH ~10) and acidic (pH ~ 5) environment. The addition rate of the precursors was varied for each group (600, 7 ou 1,5 mL/min). Furthermore, the effects of posterior heat treatments in the range of 200–800 ºC on the properties of pure HA, and at 600 ºC and 1100 ºC with normal cooling step, as well as followed by a quenching procedure at liquid N2 for HAEu were also evaluated. The materials structural and compositional characteristics were evaluated by X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared (FTIR) and RAMAN spectroscopies, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and thermogravimetric analysis (TG). The morphological aspects were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electronic and optical properties were evaluated by ultraviolet-visible spectroscopy (UV-Vis), fluorescence spectroscopy, and time-resolved fluorescence line narrowing technique spectroscopy (TRFLN). TRFLN technique was realized in order to collect site-selective information of Eu3+ environments in HA structure. The formation of HA nano and microparticles with distinct degrees of structural ordering, particle sizes and shapes, through changing the synthesis parameters was confirmed. Moreover, a single phase of HAEu was obtained. The posterior heat treatments were crucial on the final characteristics of HA and HAEu. The PL emissions of pure samples have a broad band profile typical from structural defects, with tunable colors, including blue, yellow, bluish-white, and yellowish-white colors. This result demonstrates that intense and stable emissions, besides the characteristic blue emission of the material, are possible for HA by using a simple and cheap methodology. MTT assays of pure HA samples with enhanced intrinsic PL in human dermal fibroblasts neonatal (HDFn) shows high cell viability. The internalization capability of these samples (cell uptake) and cell labelling by the intrinsic PL were evaluated by confocal microscopy, and showed promising results for bioimage procedures. The PL studies of Eu3+ in HA were effective on reveal site-selective information for three environments for this specie in the precipitated sample. After the heat treatments, the Eu3+ concentration in each site changes, and by using the quenching step it was evidenced the preference for only one site.
- español
