Desenvolvimento de pontos quânticos de Gd3+/ZnO conjugados a pontos quânticos de GCIS/ZnS para imagens multimodais associados à nanocápsulas lipídicas
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Data
2022-02-09
Autores
Silva, Bruna Lallo da
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Universidade Estadual Paulista (Unesp)
Resumo
Nos últimos anos, o uso de pontos quânticos (PQs) para obter imagens biológicas tem atraído atenção por suas propriedades luminescentes e a possibilidade de incorporar agentes de contraste para serem utilizados em imagens de ressonância magnética. Nessa tese, foram utilizadas diferentes estratégias para o desenvolvimento de PQs objetivando a aplicação no diagnóstico por meio de imagens óticas e de ressonância magnética. Dessa forma, PQs de ZnO e PQs de ZnOGd foram sintetizados pela rota sol-gel. PQs contendo gadolínio-cobre-índio-enxofre e ZnS (GCIS/ZnS) foram sintetizados através de duas rotas de síntese (rota 1 e rota 2). Os PQs de ZnO e ZnOGd foram conjugados com PQs de GCIS/ZnS por meio de um tratamento térmico, resultando em um novo ponto quântico não previamente descrito na literatura. Os PQs foram caracterizados através das técnicas de Microscopia eletrônica de transmissão (MET), espectroscopia na região do infravermelho (FTIR), difração de raios X (DRX), análise termogravimétrica, espectroscopia de absorção na região do ultravioleta-visível (UV-Vis). A avaliação das propriedades fotoluminescentes foi realizada por meio da coleta dos espectros de excitação (PLE) e emissão (PL). Os PQs de ZnOGd-GCIS/ZnS foram associados às automontagens de arginina (Arg) e ferrocifeno (p-54) e às nanocápsulas lipídicas (NCL). Para a associação com as NCL, os PQs foram modificados por Hexadeciltrimetoxisilano (HTMS) para permitir sua dispersão em Labrafac® (triglicerídeos de ácido cáprico-caprílico), constituinte da fase oleosa das NCL, que foram preparadas através do método de inversão de fases. Ainda, uma modificação hidrofílica nos PQs foi realizada usando o 3-glicidiloxipropiltrimetoxisilano (GPTMS) para a dispersão dos PQs em água. As propriedades de imagens tanto dos PQs associados às NCL quanto dos PQs dispersos em água foram avaliadas através de imagens de ressonância magnética e coleta dos espectros de PLE e PL. As propriedades citotóxicas e de captação celular foram determinadas frente às células de fibroblasto embrionário de camundongo (NIH/3T3-ATCC® CRL-1658 ™). Os resultados mostraram que os pós de ZnOGd-GCIS/ZnS tratados termicamente podem ser excitados em diferentes regiões. Dessa forma, os PQs interagem entre si de forma a mudar as propriedades luminescentes tanto do ZnOGd quanto do GCIS/ZnS (rota 1), sendo que o máximo de emissão ficou entre a emissão dos dois PQs separadamente. A associação dos PQs de ZnOGd-GCIS/ZnS com Arg-p54 resultou na perda da luminescência. Diferentes proporções entre ZnOGd e GCIS/ZnS (rota 1) foram incorporadas nas NCL e apresentaram bom contraste nas imagens de ressonância magnética. Os novos PQs desenvolvidos (ZnOGd-GCIS/ZnS), dispersos em água, maioritariamente constituído por ZnOGd (75%), apresentaram menor citotoxicidade quando comparado ao ZnOGd, além de maior captação celular. Ainda, as NCL associadas aos PQs apresentaram maior citotoxicidade e menor captação celular que comparados com os PQs sozinhos. A síntese do GCIS/ZnS foi otimizada (rota 2), resultando em PQs com maior grau de pureza. Após a associação do GCIS/ZnS (rota 2) com os PQs de ZnOGd por meio do tratamento térmico, foram encontradas emissões na primeira janela do infravermelho próximo, chegando até 820 nm, conforme aumentou a proporção de GCIS/ZnS em relação ao ZnO Gd. Essa emissão no infravermelho próximo é mais favorável para imagens biológicas pois tem maior penetração nos tecidos além de ser uma região de emissão que se diferencia da autofluorescência das células. Frente aos resultados apresentados, podemos concluir que os PQs desenvolvidos contendo uma associação entre ZnOGd e GCIS/ZnS por meio do tratamento térmico, tanto dispersos em água quanto associados às NCL, apresentam grande potencial para o diagnóstico simultâneo por imagens de ressonância magnética e imagens de luminescência.
In the last years, the use of quantum dots (Qdots) to obtain biological images has stand out due to their luminescent properties and the possibility to incorporated contrast agents to be used in magnetic resonance images. In this thesis, different strategies were used for the Qdots development aiming the application in the diagnosis through optical and magnetic resonance imaging. Thus, ZnO Qdots and ZnOGd Qdots were synthesized by the sol-gel method. Qdots containing gadolinium-copper-indium-sulfur and ZnS (GCIS/ZnS) were synthesized through two synthesis routes (route 1 and route 2). The ZnO and ZnOGd Qdots were conjugated with Qdots containing gadolinium-copper-indium-sulfur and ZnS (GCIS/ZnS) through a heat treatment, resulting in a new quantum dot not previously described in the literature. Qdots were characterized by transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD) thermogravimetric analysis (TG) and absorption spectroscopy in the ultraviolet-visible region (UV-vis). The photoluminescent properties were evaluated by excitation (PLE) and emission (PL) spectra. The ZnOGd-GCIS/ZnS Qdots were associated with self-assemblies of arginine (Arg) and ferrocifen (p-54) and lipid nanocapsules (LNC). ZnOGd-GCIS/ZnS Qdots were modified by Hexadeciltrimetoxisilane (HTMS) to allow their dispersion in labrafac® (caprylic-capric acid triglycerides), oil phase constituent of LNC, in which were prepared by phase inversion method. Furthermore, a hydrophilic Qdots modification was carried out using 3-glycidyloxypropyltrimethoxysilane (GPTMS) to disperse the Qdots in water. The image properties of NCL-associated to Qdots and water-dispersed Qdots were evaluated by magnetic resonance images and acquisition of PLE and PL spectra. The cytotoxic and cell uptake properties were determined against mouse embryonic fibroblast cells (NIH/3T3-ATCC® CRL-1658 ™). The results showed that the heat-treated ZnOGdGCIS/ZnS powders can be excited in different regions. In this way, Qdots interact with each other changing the luminescent properties of both ZnOGd and GCIS/ZnS (route 1) and the maximum emission was between the emission of the two Qdots separately. The association of ZnOGd-GCIS/ZnS Qdots with Arg-p54 resulted in loss of luminescence. The new Qdots developed (ZnOGd-GCIS/ZnS), dispersed in water, mainly constituted by ZnOGd (75%), showed lower cytotoxicity when compared to ZnOGd, in addition to greater cellular uptake. Furthermore, the NCL associated with the Qdots showed greater cytotoxicity and lower cellular uptake than compared to the Qdots alone. The GCIS/ZnS synthesis was optimized (route 2), resulting in Qdots with a higher purity. After the association of GCIS/ZnS (route 2) with the ZnOGd Qdots through heat treatment, emissions were found in the first near-infrared window, reaching up to 820 nm, as the proportion of GCIS/ZnS in relation to ZnOGd increased. This near-infrared emission is more favorable for biological imaging as it has greater penetration into tissues in addition to being an emission region that differs from the autofluorescence of cells. Based on the results presented, we can conclude that the developed Qdots containing an association between ZnOGd and GCIS/ZnS through thermal treatment, dispersed in water or associated with NCL, have great potential for simultaneous diagnosis by magnetic resonance imaging and luminescence.
In the last years, the use of quantum dots (Qdots) to obtain biological images has stand out due to their luminescent properties and the possibility to incorporated contrast agents to be used in magnetic resonance images. In this thesis, different strategies were used for the Qdots development aiming the application in the diagnosis through optical and magnetic resonance imaging. Thus, ZnO Qdots and ZnOGd Qdots were synthesized by the sol-gel method. Qdots containing gadolinium-copper-indium-sulfur and ZnS (GCIS/ZnS) were synthesized through two synthesis routes (route 1 and route 2). The ZnO and ZnOGd Qdots were conjugated with Qdots containing gadolinium-copper-indium-sulfur and ZnS (GCIS/ZnS) through a heat treatment, resulting in a new quantum dot not previously described in the literature. Qdots were characterized by transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD) thermogravimetric analysis (TG) and absorption spectroscopy in the ultraviolet-visible region (UV-vis). The photoluminescent properties were evaluated by excitation (PLE) and emission (PL) spectra. The ZnOGd-GCIS/ZnS Qdots were associated with self-assemblies of arginine (Arg) and ferrocifen (p-54) and lipid nanocapsules (LNC). ZnOGd-GCIS/ZnS Qdots were modified by Hexadeciltrimetoxisilane (HTMS) to allow their dispersion in labrafac® (caprylic-capric acid triglycerides), oil phase constituent of LNC, in which were prepared by phase inversion method. Furthermore, a hydrophilic Qdots modification was carried out using 3-glycidyloxypropyltrimethoxysilane (GPTMS) to disperse the Qdots in water. The image properties of NCL-associated to Qdots and water-dispersed Qdots were evaluated by magnetic resonance images and acquisition of PLE and PL spectra. The cytotoxic and cell uptake properties were determined against mouse embryonic fibroblast cells (NIH/3T3-ATCC® CRL-1658 ™). The results showed that the heat-treated ZnOGdGCIS/ZnS powders can be excited in different regions. In this way, Qdots interact with each other changing the luminescent properties of both ZnOGd and GCIS/ZnS (route 1) and the maximum emission was between the emission of the two Qdots separately. The association of ZnOGd-GCIS/ZnS Qdots with Arg-p54 resulted in loss of luminescence. The new Qdots developed (ZnOGd-GCIS/ZnS), dispersed in water, mainly constituted by ZnOGd (75%), showed lower cytotoxicity when compared to ZnOGd, in addition to greater cellular uptake. Furthermore, the NCL associated with the Qdots showed greater cytotoxicity and lower cellular uptake than compared to the Qdots alone. The GCIS/ZnS synthesis was optimized (route 2), resulting in Qdots with a higher purity. After the association of GCIS/ZnS (route 2) with the ZnOGd Qdots through heat treatment, emissions were found in the first near-infrared window, reaching up to 820 nm, as the proportion of GCIS/ZnS in relation to ZnOGd increased. This near-infrared emission is more favorable for biological imaging as it has greater penetration into tissues in addition to being an emission region that differs from the autofluorescence of cells. Based on the results presented, we can conclude that the developed Qdots containing an association between ZnOGd and GCIS/ZnS through thermal treatment, dispersed in water or associated with NCL, have great potential for simultaneous diagnosis by magnetic resonance imaging and luminescence.
Descrição
Palavras-chave
Pontos Quânticos, Nanocápsulas Lipídicas, Imagens Multimodais, Luminescência, Ressonância Magnética, Quantum dots, Multimodal Images, Magnetic resonance imaging