Nanopartículas de ouro têm mostrado enorme potencial de aplicação em modalidades diagnósticas e terapêuticas fotoativadas. Em especial, nanoestruturas de ouro anisotrópicas ramificadas apresentam excelente desempenho atuando tanto como contrastes de imagens fotoacústicas, quanto como agentes ativos para terapias fototérmicas de câncer. Apesar dos avanços nas suas rotas de síntese, o desenvolvimento dessas nanoestruturas de forma simples e reprodutível ainda é desafiador. O presente trabalho visou o desenvolvimento de nanopartículas de ouro anisotrópicas ramificadas, ou nanoflores, que sejam fotoativas no infravermelho-próximo para a terapia e diagnóstico de câncer. Em particular, buscou-se o desenvolvimento de uma síntese simples para sua obtenção, assim como a verificação de sua atuação como agente de contraste fotoacústico e como agente ativo para hipertermia de tumores. Para tanto, desenvolveu-se uma síntese in situ que permitiu a obtenção de nanoflores monodispersas com tamanho e propriedades ópticas controláveis. Através da variação de aspectos da síntese, como a temperatura e a concentração de ouro, foi possível sintonizar a atividade óptica das partículas entre 590 e 960 nm. Sua formação foi confirmada por microscopia eletrônica de varredura, espalhamento de luz dinâmico e espectroscopia UV-visível. As partículas apresentaram boa estabilidade de suas características físico-químicas por dois meses e meio. Ainda, as nanoflores se mostraram estáveis, também, quando suspensas em meio de cultura, sob irradiação de lasers, e quando mantidas a temperatura corpórea por longos intervalos. Sua resposta fotoacústica foi caracterizada, apresentando sinais significativos e permitindo a obtenção de imagens claras de sua localização, mesmo em baixas concentrações. Testes realizados em cultura de células mostraram que as nanoflores foram eficazes na hipertermia de uma linhagem de hepatocarcinoma de rato (HTC), ao mesmo tempo que não apresentaram sinais de toxicidade a uma linhagem de fibroblastos de camundongos (FC3H). Esses resultados revelam uma possibilidade simples de fabricação de nanoestruturas de ouro anisotrópicas ramificadas, que podem servir como uma plataforma promissora para o diagnóstico e terapia do câncer. / Gold nanoparticles have shown enormous potential of application in photodiagnostic and in phototherapeutic procedures. Notably, branched anisotropic gold nanostructures present distinguished performance acting as contrast agents of photoacoustic images and as active agents for photothermal therapies for cancer. Despite advances in their synthesis routes, the growth of these nanostructures in a simple and reproducible way is still challenging. The present study was aimed at developing branched anisotropic gold nanoparticles, coined nanoflowers, that are photoactive in the near-infrared for therapy and diagnosis of cancer. In particular, we sought to develop a simple synthesis route, as well as to verify its application for both, as photoacoustic contrast agents and as active agents for tumor hyperthermia. An in situ synthesis was developed which allowed the development of monodisperse nanoflowers with controllable size and optical properties. Through variations of certain aspects of this procedure, such as temperature and gold ions concentration, it was possible to tune the optical activity of the particles between 590 and 960 nm. The nanostructure morphology was confirmed by scanning electron microscopy, dynamic light scattering and UV-visible spectroscopy. The particles exhibited consistent physicochemical characteristics and good stability for two and a half months. Furthermore, the nanoflowers were also stable when suspended in cell culture medium, under laser irradiation and when maintained at body temperature for long intervals. Its photoacoustic response was characterized, presenting significant responses and generating clear images of its location, even at low concentrations. In vitro tests revealed that these nanoflowers were effective therapeutic agents for photothermal therapy of a rat hepatocarcinoma (HTC) lineage, while showing no signs of toxicity to mouse fibroblast (FC3H) cell line. These results reveal a simple procedure of synthesizing branched anisotropic gold nanostructures, which can serve as a promising platform for cancer diagnosis and therapy.

Nanopartículas de ouro têm mostrado enorme potencial de aplicação em modalidades diagnósticas e terapêuticas fotoativadas. Em especial, nanoestruturas de ouro anisotrópicas ramificadas apresentam excelente desempenho atuando tanto como contrastes de imagens fotoacústicas, quanto como agentes ativos para terapias fototérmicas de câncer. Apesar dos avanços nas suas rotas de síntese, o desenvolvimento dessas nanoestruturas de forma simples e reprodutível ainda é desafiador. O presente trabalho visou o desenvolvimento de nanopartículas de ouro anisotrópicas ramificadas, ou nanoflores, que sejam fotoativas no infravermelho-próximo para a terapia e diagnóstico de câncer. Em particular, buscou-se o desenvolvimento de uma síntese simples para sua obtenção, assim como a verificação de sua atuação como agente de contraste fotoacústico e como agente ativo para hipertermia de tumores. Para tanto, desenvolveu-se uma síntese in situ que permitiu a obtenção de nanoflores monodispersas com tamanho e propriedades ópticas controláveis. Através da variação de aspectos da síntese, como a temperatura e a concentração de ouro, foi possível sintonizar a atividade óptica das partículas entre 590 e 960 nm. Sua formação foi confirmada por microscopia eletrônica de varredura, espalhamento de luz dinâmico e espectroscopia UV-visível. As partículas apresentaram boa estabilidade de suas características físico-químicas por dois meses e meio. Ainda, as nanoflores se mostraram estáveis, também, quando suspensas em meio de cultura, sob irradiação de lasers, e quando mantidas a temperatura corpórea por longos intervalos. Sua resposta fotoacústica foi caracterizada, apresentando sinais significativos e permitindo a obtenção de imagens claras de sua localização, mesmo em baixas concentrações. Testes realizados em cultura de células mostraram que as nanoflores foram eficazes na hipertermia de uma linhagem de hepatocarcinoma de rato (HTC), ao mesmo tempo que não apresentaram sinais de toxicidade a uma linhagem de fibroblastos de camundongos (FC3H). Esses resultados revelam uma possibilidade simples de fabricação de nanoestruturas de ouro anisotrópicas ramificadas, que podem servir como uma plataforma promissora para o diagnóstico e terapia do câncer. / Gold nanoparticles have shown enormous potential of application in photodiagnostic and in phototherapeutic procedures. Notably, branched anisotropic gold nanostructures present distinguished performance acting as contrast agents of photoacoustic images and as active agents for photothermal therapies for cancer. Despite advances in their synthesis routes, the growth of these nanostructures in a simple and reproducible way is still challenging. The present study was aimed at developing branched anisotropic gold nanoparticles, coined nanoflowers, that are photoactive in the near-infrared for therapy and diagnosis of cancer. In particular, we sought to develop a simple synthesis route, as well as to verify its application for both, as photoacoustic contrast agents and as active agents for tumor hyperthermia. An in situ synthesis was developed which allowed the development of monodisperse nanoflowers with controllable size and optical properties. Through variations of certain aspects of this procedure, such as temperature and gold ions concentration, it was possible to tune the optical activity of the particles between 590 and 960 nm. The nanostructure morphology was confirmed by scanning electron microscopy, dynamic light scattering and UV-visible spectroscopy. The particles exhibited consistent physicochemical characteristics and good stability for two and a half months. Furthermore, the nanoflowers were also stable when suspended in cell culture medium, under laser irradiation and when maintained at body temperature for long intervals. Its photoacoustic response was characterized, presenting significant responses and generating clear images of its location, even at low concentrations. In vitro tests revealed that these nanoflowers were effective therapeutic agents for photothermal therapy of a rat hepatocarcinoma (HTC) lineage, while showing no signs of toxicity to mouse fibroblast (FC3H) cell line. These results reveal a simple procedure of synthesizing branched anisotropic gold nanostructures, which can serve as a promising platform for cancer diagnosis and therapy.

Dans les domaines de l’imagerie médicale et la thérapie, l’utilisation des nanoparticules est spécialement attrayante et prometteuse. Il est possible de concentrer dans une même particule plusieurs fonctions complémentaires comme la détection, le ciblage mais aussi la thérapie. Cette multifonctionnalité présente de nombreux avantages, et favorise le développement de nanoparticules pour une thérapie ciblée et guidée par l’imagerie.C’est dans ce contexte d’intense activité centrée sur le développement des nanoparticules pour les applications médicales (imagerie et/ou thérapie) que s’est déroulé mon travail de thèse qui s’inscrit dans la continuité des travaux de Christophe Alric et de Pierre Hugounenq. Ils ont développé respectivement des nanoparticules d’or multifonctionnelles (Au@DTDTPA) et des nanofleurs d’oxyde de fer (γ-Fe2O3).Les nanoparticules d’or (Au@DTDTPA) présentent un effet radiosensibilisant et se comportent comme agent de contraste pour l’IRM (après marquage par Gd3+ rendu possible par les propriétés chélatantes de la couche organique DTDTPA) ou comme radiotraceurs après radiomarquage (le DTDTPA forme des complexes stables avec 99mTc et 111In). Le caractère superparamagnétique des nanofleurs d’oxyde de fer confèrent à ces objets la capacité à rehausser le contraste négatif des images et à induire un échauffement sous l’action d’un champ magnétique alternatif de haute fréquence.L’objectif principal de ma thèse consistait à assembler ces deux types de nanoparticules afin de créer un objet nanométrique combinant les propriétés complémentaires des nanoparticules d’or et des nanofleurs d’oxyde de fer. Dans un premier temps, les conditions optimales de greffage des nanoparticules d’or sur les nanofleurs ont été déterminées. Nous avons montré que de tels agents présentaient après injection intraveineuse une biodistribution adaptée comme le révèlent les images acquises en IRM (grâce aux propriétés magnétiques des nanofleurs) et en TEMP (grâce au radiomarquage de la couche des nanoparticules d’or). En outre ces objets présentent un caractère radiosensibilisant qui est mieux exploité que celui des nanoparticules d’or entrant dans la composition de ces nanofleurs dorées. Associé au pouvoir chauffant des nanofleurs, le pouvoir radiosensibilisant des nanofleurs dorées a conduit à une forte inhibition de la croissance tumorale quand le traitement de rats portant un mélanome combine hyperthermie magnétique et radiothérapie après injection intratumorale des nanofleurs dorées.En conclusion, le travail réalisé au cours de cette thèse a mis en évidence l’intérêt de combiner les nanoparticules d’or et les nanofleurs d’oxyde de fer pour traiter des tumeurs solides par thérapie guidée par imagerie. / In the fields of medical imaging and therapy, the use of nanoparticles is especially attractive and promising. It is possible to concentrate in the same particle several complementary functions such as detection, targeting but also therapy. This multifunctionality has many advantages and promotes the development of nanoparticles for targeted therapy and guided by medical imaging.It is in this context of intense activity focused on the development of nanoparticles for medical applications (imaging and/or therapy) that my thesis work was carried out which is in continuity with the work of Christophe Alric and Pierre Hugounenq. They developed multifunctional gold nanoparticles (Au@DTDTPA) and iron oxide nanoflowers (γ-Fe2O3), respectively.The gold nanoparticles (Au @ DTDTPA) exhibit a radiosensitizing effect and behave as a contrast agent for MRI (after labeling with Gd3 +, made possible by the chelating properties of the organic layer DTDTPA) or radiotracers after radiolabelling (DTDTPA forms stable complexes with 99mTc and 111In). The superparamagnetic nature of the iron oxide nanoflowers gives these objects the ability to enhance the negative contrast of the images and to induce heating under the action of an alternating magnetic field of high frequency.The main objective of my thesis was to assemble these two types of nanoparticles in order to create a nanometric object combining the complementary properties of gold nanoparticles and iron oxide nanoflowers. In a first step, the optimal conditions for grafting gold nanoparticles on the nanoflower were determined. We have shown that, after intravenous injection, these agents exhibit a suitable biodistribution, as revealed by MRI images (thanks to the magnetic properties of nanoflowers) and SPECT (thanks to the radiolabeling of the gold nanoparticle layer). Moreover, these objects have a radiosensitizing character which is better exploited than that of the gold nanoparticles in the golden nanoflowers. Associated with the heating power of nanoflower, the radiosensitizing potential of golden nanoflowers has led to a strong inhibition of tumor growth when the treatment of rats carrying melanoma combines magnetic hyperthermia and radiotherapy after injection of golden nanoflower.In conclusion, the work carried out during this thesis has highlighted the value of combining gold nanoparticles and iron oxide nanoflowers to treat solid tumors by imaging-guided therapy.

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