Novel luminescent In-based lead-free double halide perovskites co-doped with Yb3+/Er3+ have been ... more Novel luminescent In-based lead-free double halide perovskites co-doped with Yb3+/Er3+ have been synthesized. Their primary thermometer performance was assessed and their biological application to predict temperature was evaluated.
Latin America Optics and Photonics (LAOP) Conference 2022
YAG (Yttrium Aluminum Garnet) spheres doped with different lanthanide ions were obtained via Spra... more YAG (Yttrium Aluminum Garnet) spheres doped with different lanthanide ions were obtained via Spray Pyrolysis. The Nd3+:YAG particles were studied for their stimulated emissions in disordered environments, while Yb3+/Er3+:YAG were intended for studies at different temperatures.
Latin America Optics and Photonics (LAOP) Conference 2022
We report a new synthesis route to prepare YAB:Nd particles, on the basis of the urea precipitati... more We report a new synthesis route to prepare YAB:Nd particles, on the basis of the urea precipitation method. The results confirmed the trigonal symmetry and the stimulated emission leading to random lasing in the powder.
International Journal of Advances in Medical Biotechnology - IJAMB
The silk produced in the Bombyx mori’ glands and used in the preparation of the cocoons has been ... more The silk produced in the Bombyx mori’ glands and used in the preparation of the cocoons has been employed in the textile industry millennia ago in fabric production. These cocoons are composed mainly of fibroin (SF, Silk Fibroin), a fibrous protein that presents unique mechanical properties, in addition to being a biocompatible, biodegradable and low-cost source. This protein can be extracted from these cocoons by being processed in aqueous medium and used to obtain the most diverse materials for different applications, such as biomaterials development as body implants and in the composition of the scaffolds for tissue engineering, moreover to photonic devices as sensors, waveguides and lasers.
A fibroína da seda (SF) é uma proteína estrutural encontrada nos casulos do Bombyx mori e que pos... more A fibroína da seda (SF) é uma proteína estrutural encontrada nos casulos do Bombyx mori e que possui propriedades potencialmente aplicáveis em fotônica. Esta matriz biocompatível é um substrato interessante para diferentes íons ou moléculas; além disso, o seu índice de refração variável permite que fótons sejam guiados neste material, possibilitando seu uso como guias de ondas biocompatíveis e reabsorvíveis, que pode ser utilizado para fornecer energia ótica para diversas aplicações, por exemplo, terapia ou imagem dentro de tecidos vivos. A sua boa adequação em sistemas ópticos deve-se principalmente a propriedades como: ser mecanicamente robusta, apresentar superfícies muito lisas, altamente transparentes (> 95%) em toda a região visível do espectro e ser modelável. Além disto, há uma característica adicional: a viabilidade de funcionalização bioquímica, o que pode conferir uma maior versatilidade a estes dispositivos. Já os íons terras raras (TR) possuem um papel amplamente con...
, pelo apoio em cada passo dado nesta trajetória, por ter me ensinado grande parte do que sei sob... more , pelo apoio em cada passo dado nesta trajetória, por ter me ensinado grande parte do que sei sobre química e, principalmente, pela relação de amizade e respeito construída durante estes 11 anos de trabalho. Agradeço também pelo apoio, compreensão e paciência nos momentos difíceis, e por ter me dado a certeza de que o NanoLum era o meu lugar. Estendo meus agradecimentos à Silvana, pelo carinho, educação e respeito com que trata a todos nós. Obrigada também, Sil, pela paciência durante os encontros do nosso grupo. À minha mãe, Helena, que desde muito cedo me ensinou a importância da educação, principalmente para nós mulheres, e que nunca mediu esforços para que tivéssemos acesso a tudo que precisássemos, para chegar onde quiséssemos. Por mais clichê que posso parecer, sem você, sua força e resiliência, esta trajetória não estaria chegando ao fim. Obrigada, mais uma vez, por fazer das nossas vidas a sua vida, e dos nossos sonhos os seus sonhos. Ao Ricardo, meu irmão, amigo e a base mais sólida da minha vida. Obrigada por segurar sozinho as "barras" que seriam nossas, e desviar o seu caminho para que eu pudesse seguir no meu. Jamais serei capaz de expressar a minha gratidão, pois, sem você e seu apoio, eu não estaria aqui escrevendo esta tese. Ao Fer, que compartilha comigo todas as alegrias e tristezas da vida. Obrigada pelas nossas infinitas conversas, por me apoiar em absolutamente tudo, vibrar com minhas conquistas como se fossem tuas e, por muitas vezes, trazer a calma que falta em mim. Estendo minha gratidão à sua família, Maria, Du, Tha, Tami e Thi, obrigada por me acolherem e por se tornarem minha segunda família desde o início. Aos meus tios, Sônia e Zé, pelo apoio e presença durante toda minha vida. Agradeço também pelo acolhimento nos momentos difíceis, e por tudo que fizeram por nós. Neste sentido, agradeço também a Tati e a Tia Marlene por se fazerem presentes, cada uma a sua maneira, quando mais foi necessário. Às minhas primas e, não por coincidência, melhores amigas, Carol, Mari e Vivi, por tudo que compartilhamos durante toda a vida. Vocês são as irmãs que, de fato, eu não tive. Aos meus amigos, Camila,
Random lasers (RLs) are remarkable experimental platforms to advance the understanding of complex... more Random lasers (RLs) are remarkable experimental platforms to advance the understanding of complex systems phenomena, such as the replica-symmetry-breaking (RSB) spin glass phase, dynamics modes correlations, and turbulence. Here we study these three phenomena jointly in a Nd:YAG based RL synthesized for the first time using a spray pyrolysis method. We propose a couple of modified Pearson correlation coefficients that are simultaneously sensitive to the emergence and fading out of photonic intermittency turbulent-like effects, dynamics evolution of modes correlations, and onset of RSB behavior. Our results show how intertwined these phenomena are in RLs, and suggest that they might share some common underlying mechanisms, possibly approached in future theoretical models under a unified treatment.
Abstract This work proposes a smart way to produce lanthanide-doped alumina and yttrium spherical... more Abstract This work proposes a smart way to produce lanthanide-doped alumina and yttrium spherical compounds. We were able to tune the structure of the Al2O3-yttrium binary material prepared herein by controlling the Y3+/Al3+ ratio. Small ratio (Y0.1/Al1 mol/mol) afforded the metastable hexagonal phase (YAlO3), which remained stable in the final product even after thermal treatment at 1100 °C. On the basis of XRD data, increasing Y3+/Al3+ ratio led to the formation of the crystalline YAG phase after thermal treatment. The luminescence data showed that Eu3+ ions doped into the binary material were highly sensitive to changes in the environment around the Eu3+ ion, and the emission spectra corroborated that the latter ion migrated to yttrium sites in the YAG structure. The luminescence confirmed the presence of a secondary Eu3+ ion coordination site in the material, but at higher Y3+/Al3+ ratio, the YAG structure has predominated.
Abstract Nd3+:YAG crystals have been used to develop photonic devices since the 1960s. Its unique... more Abstract Nd3+:YAG crystals have been used to develop photonic devices since the 1960s. Its unique properties, which stem from the combination of the YAG structure with lanthanide ions, have made it the most widely employed material in commercial solid-state lasers. This work reports the synthesis of dense Nd3+:YAG particles prepared by spray pyrolysis. During the synthesis, no clusters emerged, and the particles did not coalesce even after thermal treatment at 1100 °C. All characterization confirmed that the YAG phase was obtained as a spherical micro- and sub-micrometric material. In addition, the photoluminescence spectra showed the expected spectroscopic profile of Nd3+ replacing Y3+ at the dodecahedral sites. The presence of high Nd3+ concentration was exploited as a simultaneous gain and scatter medium for random laser application. The spray pyrolysis methodology described could be easily scaled up for a pilot setup or industrial production. Further applications as sensors or superluminescent sources can be envisaged.
This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite... more This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite films. Associating the physicochemical properties of fibroin with the spectroscopic properties of lanthanide ions can be a strategy to develop a new generation of biocompatible and biodegradable sensors with high transparency in the visible region. The results presented herein are a natural consequence of a previous study that used europium ions as structural probes in the composite fibroin matrix and investigated their potential application as photonic devices. Here, highly transparent thin films containing the silk fibroin matrix and an Eu 3+ complex were produced by dip-coating under controlled conditions. Europium thenoyltrifluoroacetonate was employed as the luminescent component of the proposed sensor. The films were characterized by electronic spectroscopy in the UV-Vis region and photoluminescence. The effect of complex insertion on the refraction index of the silk fibroin film was studied. The results showed a high-intensity emission that is characteristic of europium β-diketone chelates, and the intensity of the 5 D 0 → 7 F 2 transition depended on the ammonia vapor concentration. To understand the whole process, different composite films were prepared, and the results corroborated the potential use of this system as a photonic sensor of vapors.
A Deus pela serenidade nos momentos difíceis desta caminhada. Ao meu orientador, Prof. Dr. José M... more A Deus pela serenidade nos momentos difíceis desta caminhada. Ao meu orientador, Prof. Dr. José Maurício Almeida Caiut, pela oportunidade de ingressar no seu grupo de pesquisa, ainda na Iniciação Científica; por tudo que me ensinou e vem me ensinando desde então, por acreditar em mim e no nosso trabalho e pela amizade construída. Aos meus pais, pois, por mais clichê que possa parecer, sem eles nada seria possível; ao meu irmão Ricardo, por ser o melhor presente que ganhei na vida e meu melhor amigo. Aos meus avós, Lydia e Fernando, e a todos meus tios, tias, primos e primas, pelos momentos em família que são mais valiosos que qualquer título. À Camila por estar ao meu lado desde sempre, tornando a caminhada mais leve; ao Felipe por me socorrer nos momentos difíceis e à Mari pelo companheirismo e ajuda durante este período. As minhas parceiras de Mestrado, Carol e a Larissa, por tudo que compartilhamos ao longo destes dois anos. Sem vocês com certeza teria sido muito mais difícil e bem menos divertido. A todos os amigos do "nanolum": André, João, Douglas, Fernando, Elô, Renata e Euzane, e a todos que já passaram pelo laboratório e que de alguma forma contribuíram para a realização deste projeto. À Profª. Drª. Rogéria Rocha Gonçalves por ter mantido as portas de seu laboratório sempre abertas a nós, pelos ensinamentos, contribuições e por ser um exemplo de competência e amor à profissão. Á Profª. Drª. Sofia Nikolaou e a todos seus alunos pela convivência, amizade e aprendizados diários. À Profª. Drª. Ana Paula Ramos pela amizade, disponibilidade e participação na minha formação. Ao Prof. Dr. Arthur Henrique Cavalcante de Oliveira pela contribuição durante o exame de qualificação. Ao Prof. Dr. Osvaldo Serra pelo uso dos equipamentos. Ao Prof. Dr. Sidney José Lima Ribeiro pelas contribuições, disponibilidade e uso de seu laboratório e equipamentos.
Journal of Materials Science: Materials in Electronics, 2019
Silk fibroin (SF) is a structural protein found in Bombyx mori cocoons and has properties that ar... more Silk fibroin (SF) is a structural protein found in Bombyx mori cocoons and has properties that are potentially applicable in photonics. This biocompatible matrix is an interesting substrate for different ions and molecules. Furthermore, its variable refractive index allows photons to be guided in this material enabling their use as biocompatible and resorbable waveguides, which can be used to provide optical energy for various applications, e.g., therapy or imaging in living tissue. Rare earth ions (RE) play a widely known role in the field of photonics. However, there are few studies involving the production of light in doped SF with RE ions, and the literature results have shown different sensitization of Eu 3+ and Tb 3+ ions by the SF matrix. This study presented a consistent work on material synthesis, related studies on spectroscopy of RE ions, and the role of beta-diketonate ligand on the energy transfer mechanisms with the emission improvement in the investigated material. As a result, an intensification of emission was observed for Eu 3+ doped sample in the presence of 2-thenoyltrifluoroacetone ligand, but similar results were not carried out with acetylacetone ligand insertion. A possible cause was the different access by beta-diketonate to the lanthanide ion in SF matrix due to the ligand-SF interaction. The results presented have characterized the RE-SF interactions and supported the mechanisms of energy transfer improvement for excitation of different RE ions in this matrix being important for future applications in photonics.
The use of rare earth (RE)-doped materials in photonics; e.g., in solid-state lasers in the UV-vi... more The use of rare earth (RE)-doped materials in photonics; e.g., in solid-state lasers in the UV-vis NIR spectral region, in light emitting devices, and in fibers for optical amplifiers and data storage systems, is well known. Combining the mechanical and optical properties of silk fibroin (SF) with the multifunctionality of rare earth ions could be an interesting strategy to develop new, distinguished photonic devices. For this reason and given that no studies about light emission in RE-doped silk fibroin exist, here we present an innovative approach to develop photonic devices based on SF doped with RE ions, and we employ europium ion as a structural probe in a RE-doped composite SF matrix to obtain systems with better emission parameters. To this end, we prepared self-supported films consisting of RE-doped SF. The Bombyx mori SF bears aromatic amino acids, such as Tyrosine (Tyr) and Tryptophan (Trp), which display fluorescent behavior. These amino acids can function as fluorescent probes of physicochemical properties. In the presence of RE ions, these amino acids can act as sensitizer in energy transfer processes. Our results revealed RE ion emission associated with an antenna effect elicited by the 2 aromatic amino acids. We verified distinct photophysical properties for different RE ions. To understand the process, we determined the triplet state of Trp in SF, which helped to describe the energy process. The energy of the Trp triplet state allowed quite efficient energy transfer from Trp to the Tb 3+ ion. In conclusion, this research work improved our understanding of the mechanism of RE ion excitation in SF matrix. The present results will support future work on the development of new photonic systems.
Novel luminescent In-based lead-free double halide perovskites co-doped with Yb3+/Er3+ have been ... more Novel luminescent In-based lead-free double halide perovskites co-doped with Yb3+/Er3+ have been synthesized. Their primary thermometer performance was assessed and their biological application to predict temperature was evaluated.
Latin America Optics and Photonics (LAOP) Conference 2022
YAG (Yttrium Aluminum Garnet) spheres doped with different lanthanide ions were obtained via Spra... more YAG (Yttrium Aluminum Garnet) spheres doped with different lanthanide ions were obtained via Spray Pyrolysis. The Nd3+:YAG particles were studied for their stimulated emissions in disordered environments, while Yb3+/Er3+:YAG were intended for studies at different temperatures.
Latin America Optics and Photonics (LAOP) Conference 2022
We report a new synthesis route to prepare YAB:Nd particles, on the basis of the urea precipitati... more We report a new synthesis route to prepare YAB:Nd particles, on the basis of the urea precipitation method. The results confirmed the trigonal symmetry and the stimulated emission leading to random lasing in the powder.
International Journal of Advances in Medical Biotechnology - IJAMB
The silk produced in the Bombyx mori’ glands and used in the preparation of the cocoons has been ... more The silk produced in the Bombyx mori’ glands and used in the preparation of the cocoons has been employed in the textile industry millennia ago in fabric production. These cocoons are composed mainly of fibroin (SF, Silk Fibroin), a fibrous protein that presents unique mechanical properties, in addition to being a biocompatible, biodegradable and low-cost source. This protein can be extracted from these cocoons by being processed in aqueous medium and used to obtain the most diverse materials for different applications, such as biomaterials development as body implants and in the composition of the scaffolds for tissue engineering, moreover to photonic devices as sensors, waveguides and lasers.
A fibroína da seda (SF) é uma proteína estrutural encontrada nos casulos do Bombyx mori e que pos... more A fibroína da seda (SF) é uma proteína estrutural encontrada nos casulos do Bombyx mori e que possui propriedades potencialmente aplicáveis em fotônica. Esta matriz biocompatível é um substrato interessante para diferentes íons ou moléculas; além disso, o seu índice de refração variável permite que fótons sejam guiados neste material, possibilitando seu uso como guias de ondas biocompatíveis e reabsorvíveis, que pode ser utilizado para fornecer energia ótica para diversas aplicações, por exemplo, terapia ou imagem dentro de tecidos vivos. A sua boa adequação em sistemas ópticos deve-se principalmente a propriedades como: ser mecanicamente robusta, apresentar superfícies muito lisas, altamente transparentes (> 95%) em toda a região visível do espectro e ser modelável. Além disto, há uma característica adicional: a viabilidade de funcionalização bioquímica, o que pode conferir uma maior versatilidade a estes dispositivos. Já os íons terras raras (TR) possuem um papel amplamente con...
, pelo apoio em cada passo dado nesta trajetória, por ter me ensinado grande parte do que sei sob... more , pelo apoio em cada passo dado nesta trajetória, por ter me ensinado grande parte do que sei sobre química e, principalmente, pela relação de amizade e respeito construída durante estes 11 anos de trabalho. Agradeço também pelo apoio, compreensão e paciência nos momentos difíceis, e por ter me dado a certeza de que o NanoLum era o meu lugar. Estendo meus agradecimentos à Silvana, pelo carinho, educação e respeito com que trata a todos nós. Obrigada também, Sil, pela paciência durante os encontros do nosso grupo. À minha mãe, Helena, que desde muito cedo me ensinou a importância da educação, principalmente para nós mulheres, e que nunca mediu esforços para que tivéssemos acesso a tudo que precisássemos, para chegar onde quiséssemos. Por mais clichê que posso parecer, sem você, sua força e resiliência, esta trajetória não estaria chegando ao fim. Obrigada, mais uma vez, por fazer das nossas vidas a sua vida, e dos nossos sonhos os seus sonhos. Ao Ricardo, meu irmão, amigo e a base mais sólida da minha vida. Obrigada por segurar sozinho as "barras" que seriam nossas, e desviar o seu caminho para que eu pudesse seguir no meu. Jamais serei capaz de expressar a minha gratidão, pois, sem você e seu apoio, eu não estaria aqui escrevendo esta tese. Ao Fer, que compartilha comigo todas as alegrias e tristezas da vida. Obrigada pelas nossas infinitas conversas, por me apoiar em absolutamente tudo, vibrar com minhas conquistas como se fossem tuas e, por muitas vezes, trazer a calma que falta em mim. Estendo minha gratidão à sua família, Maria, Du, Tha, Tami e Thi, obrigada por me acolherem e por se tornarem minha segunda família desde o início. Aos meus tios, Sônia e Zé, pelo apoio e presença durante toda minha vida. Agradeço também pelo acolhimento nos momentos difíceis, e por tudo que fizeram por nós. Neste sentido, agradeço também a Tati e a Tia Marlene por se fazerem presentes, cada uma a sua maneira, quando mais foi necessário. Às minhas primas e, não por coincidência, melhores amigas, Carol, Mari e Vivi, por tudo que compartilhamos durante toda a vida. Vocês são as irmãs que, de fato, eu não tive. Aos meus amigos, Camila,
Random lasers (RLs) are remarkable experimental platforms to advance the understanding of complex... more Random lasers (RLs) are remarkable experimental platforms to advance the understanding of complex systems phenomena, such as the replica-symmetry-breaking (RSB) spin glass phase, dynamics modes correlations, and turbulence. Here we study these three phenomena jointly in a Nd:YAG based RL synthesized for the first time using a spray pyrolysis method. We propose a couple of modified Pearson correlation coefficients that are simultaneously sensitive to the emergence and fading out of photonic intermittency turbulent-like effects, dynamics evolution of modes correlations, and onset of RSB behavior. Our results show how intertwined these phenomena are in RLs, and suggest that they might share some common underlying mechanisms, possibly approached in future theoretical models under a unified treatment.
Abstract This work proposes a smart way to produce lanthanide-doped alumina and yttrium spherical... more Abstract This work proposes a smart way to produce lanthanide-doped alumina and yttrium spherical compounds. We were able to tune the structure of the Al2O3-yttrium binary material prepared herein by controlling the Y3+/Al3+ ratio. Small ratio (Y0.1/Al1 mol/mol) afforded the metastable hexagonal phase (YAlO3), which remained stable in the final product even after thermal treatment at 1100 °C. On the basis of XRD data, increasing Y3+/Al3+ ratio led to the formation of the crystalline YAG phase after thermal treatment. The luminescence data showed that Eu3+ ions doped into the binary material were highly sensitive to changes in the environment around the Eu3+ ion, and the emission spectra corroborated that the latter ion migrated to yttrium sites in the YAG structure. The luminescence confirmed the presence of a secondary Eu3+ ion coordination site in the material, but at higher Y3+/Al3+ ratio, the YAG structure has predominated.
Abstract Nd3+:YAG crystals have been used to develop photonic devices since the 1960s. Its unique... more Abstract Nd3+:YAG crystals have been used to develop photonic devices since the 1960s. Its unique properties, which stem from the combination of the YAG structure with lanthanide ions, have made it the most widely employed material in commercial solid-state lasers. This work reports the synthesis of dense Nd3+:YAG particles prepared by spray pyrolysis. During the synthesis, no clusters emerged, and the particles did not coalesce even after thermal treatment at 1100 °C. All characterization confirmed that the YAG phase was obtained as a spherical micro- and sub-micrometric material. In addition, the photoluminescence spectra showed the expected spectroscopic profile of Nd3+ replacing Y3+ at the dodecahedral sites. The presence of high Nd3+ concentration was exploited as a simultaneous gain and scatter medium for random laser application. The spray pyrolysis methodology described could be easily scaled up for a pilot setup or industrial production. Further applications as sensors or superluminescent sources can be envisaged.
This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite... more This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite films. Associating the physicochemical properties of fibroin with the spectroscopic properties of lanthanide ions can be a strategy to develop a new generation of biocompatible and biodegradable sensors with high transparency in the visible region. The results presented herein are a natural consequence of a previous study that used europium ions as structural probes in the composite fibroin matrix and investigated their potential application as photonic devices. Here, highly transparent thin films containing the silk fibroin matrix and an Eu 3+ complex were produced by dip-coating under controlled conditions. Europium thenoyltrifluoroacetonate was employed as the luminescent component of the proposed sensor. The films were characterized by electronic spectroscopy in the UV-Vis region and photoluminescence. The effect of complex insertion on the refraction index of the silk fibroin film was studied. The results showed a high-intensity emission that is characteristic of europium β-diketone chelates, and the intensity of the 5 D 0 → 7 F 2 transition depended on the ammonia vapor concentration. To understand the whole process, different composite films were prepared, and the results corroborated the potential use of this system as a photonic sensor of vapors.
A Deus pela serenidade nos momentos difíceis desta caminhada. Ao meu orientador, Prof. Dr. José M... more A Deus pela serenidade nos momentos difíceis desta caminhada. Ao meu orientador, Prof. Dr. José Maurício Almeida Caiut, pela oportunidade de ingressar no seu grupo de pesquisa, ainda na Iniciação Científica; por tudo que me ensinou e vem me ensinando desde então, por acreditar em mim e no nosso trabalho e pela amizade construída. Aos meus pais, pois, por mais clichê que possa parecer, sem eles nada seria possível; ao meu irmão Ricardo, por ser o melhor presente que ganhei na vida e meu melhor amigo. Aos meus avós, Lydia e Fernando, e a todos meus tios, tias, primos e primas, pelos momentos em família que são mais valiosos que qualquer título. À Camila por estar ao meu lado desde sempre, tornando a caminhada mais leve; ao Felipe por me socorrer nos momentos difíceis e à Mari pelo companheirismo e ajuda durante este período. As minhas parceiras de Mestrado, Carol e a Larissa, por tudo que compartilhamos ao longo destes dois anos. Sem vocês com certeza teria sido muito mais difícil e bem menos divertido. A todos os amigos do "nanolum": André, João, Douglas, Fernando, Elô, Renata e Euzane, e a todos que já passaram pelo laboratório e que de alguma forma contribuíram para a realização deste projeto. À Profª. Drª. Rogéria Rocha Gonçalves por ter mantido as portas de seu laboratório sempre abertas a nós, pelos ensinamentos, contribuições e por ser um exemplo de competência e amor à profissão. Á Profª. Drª. Sofia Nikolaou e a todos seus alunos pela convivência, amizade e aprendizados diários. À Profª. Drª. Ana Paula Ramos pela amizade, disponibilidade e participação na minha formação. Ao Prof. Dr. Arthur Henrique Cavalcante de Oliveira pela contribuição durante o exame de qualificação. Ao Prof. Dr. Osvaldo Serra pelo uso dos equipamentos. Ao Prof. Dr. Sidney José Lima Ribeiro pelas contribuições, disponibilidade e uso de seu laboratório e equipamentos.
Journal of Materials Science: Materials in Electronics, 2019
Silk fibroin (SF) is a structural protein found in Bombyx mori cocoons and has properties that ar... more Silk fibroin (SF) is a structural protein found in Bombyx mori cocoons and has properties that are potentially applicable in photonics. This biocompatible matrix is an interesting substrate for different ions and molecules. Furthermore, its variable refractive index allows photons to be guided in this material enabling their use as biocompatible and resorbable waveguides, which can be used to provide optical energy for various applications, e.g., therapy or imaging in living tissue. Rare earth ions (RE) play a widely known role in the field of photonics. However, there are few studies involving the production of light in doped SF with RE ions, and the literature results have shown different sensitization of Eu 3+ and Tb 3+ ions by the SF matrix. This study presented a consistent work on material synthesis, related studies on spectroscopy of RE ions, and the role of beta-diketonate ligand on the energy transfer mechanisms with the emission improvement in the investigated material. As a result, an intensification of emission was observed for Eu 3+ doped sample in the presence of 2-thenoyltrifluoroacetone ligand, but similar results were not carried out with acetylacetone ligand insertion. A possible cause was the different access by beta-diketonate to the lanthanide ion in SF matrix due to the ligand-SF interaction. The results presented have characterized the RE-SF interactions and supported the mechanisms of energy transfer improvement for excitation of different RE ions in this matrix being important for future applications in photonics.
The use of rare earth (RE)-doped materials in photonics; e.g., in solid-state lasers in the UV-vi... more The use of rare earth (RE)-doped materials in photonics; e.g., in solid-state lasers in the UV-vis NIR spectral region, in light emitting devices, and in fibers for optical amplifiers and data storage systems, is well known. Combining the mechanical and optical properties of silk fibroin (SF) with the multifunctionality of rare earth ions could be an interesting strategy to develop new, distinguished photonic devices. For this reason and given that no studies about light emission in RE-doped silk fibroin exist, here we present an innovative approach to develop photonic devices based on SF doped with RE ions, and we employ europium ion as a structural probe in a RE-doped composite SF matrix to obtain systems with better emission parameters. To this end, we prepared self-supported films consisting of RE-doped SF. The Bombyx mori SF bears aromatic amino acids, such as Tyrosine (Tyr) and Tryptophan (Trp), which display fluorescent behavior. These amino acids can function as fluorescent probes of physicochemical properties. In the presence of RE ions, these amino acids can act as sensitizer in energy transfer processes. Our results revealed RE ion emission associated with an antenna effect elicited by the 2 aromatic amino acids. We verified distinct photophysical properties for different RE ions. To understand the process, we determined the triplet state of Trp in SF, which helped to describe the energy process. The energy of the Trp triplet state allowed quite efficient energy transfer from Trp to the Tb 3+ ion. In conclusion, this research work improved our understanding of the mechanism of RE ion excitation in SF matrix. The present results will support future work on the development of new photonic systems.
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Papers by Roberta Pugina