Multifunctional plasmonic nanoparticles have shown extraordinary potential for near infrared photothermal and triggered-therapeutic release treatments of solid tumors. However, the accumulation rate of the nanoparticles in the target tissue, which depends on their capacity to escape the immune system, and the ability to efficiently and accurately track these particles in vivo are still limited. To address these challenges, we have created two different systems. The first one is a multifunctional nanocarrier in which PEG-coated gold nanorods were grouped into natural cell membrane vesicles from lung cancer cell membranes (A549) and loaded with β-lap (CM-β-lap-PEG-AuNRs). Our goal was to develop specific multifunctional systems for cancer treatment by using the antigens and the unique properties of the cancer cell membrane combined with photothermal properties of AuNRs and anticancer activity of β-lap. The results confirmed the assembly of PEG-AuNRs inside the vesicles and the irradiation with NIR laser led to disruption of the vesicles and release of the PEG-AuNRs and β-Lap. In vitro studies revealed an enhanced and synergic cytotoxicity against A549 cancer cells, which can be attributed to the specific cytotoxicity of β-Lap combined with heat generated by laser irradiation of the AuNRs. No cytotoxicity was observed in absence of laser irradiation. In the second system, MRI-active Au nanomatryoshkas were developed. These are Au core-silica layer-Au shell nanoparticles, where Gd(III) ions are encapsulated within the silica layer between the inner core and outer Au layer of the nanoparticle (Gd-NM). This theranostic nanoparticle retains its strong near infrared optical absorption properties, essential for in vivo photothermal cancer therapy, while simultaneously providing increased T1 contrast in MR imaging by concentrating Gd(III) within the nanoparticle. Measurements of Gd-NM revealed a substantially enhanced T1 relaxivity (r1 ~ 17 mM-1 s-1) even at 4.7 T, surpassing conventional Gd(III)-DOTA chelating agents (r1 ~ 4 mM-1 s-1) currently in clinical use. The observed relaxivities are consistent with Solomon-Bloembergen-Morgan (SBM) theory, describing the longer-range interactions between the Gd(III) and protons outside the nanoparticle. These novel multifunctional systems open the door for the development of more efficient nanoplatforms for diagnosis and treatment of cancer. / Nanopartículas plasmônicas multifuncionais têm revelado elevado potencial para fototermia na região (NIR) do infravermelho e liberação controlada de fármacos para o tratamento de tumores sólidos. No entanto, a taxa de acumulação das nanoparticulas no tecido alvo, que depende da capacidade delas de escapar do sistema imunológico, e a habilidade de rastrear de maneira efetiva essas partículas in vivo ainda são limitadas. Para superar essas barreiras, dois sistemas diferentes foram desenvolvidos. O primeiro corresponde a um nanocarreador multifunctional, onde nanobastões de ouro funcionalizados com PEG foram agrupados dentro de vesículas de membranas de células naturais originarias de células cancerígenas de pulmão (A549) conjugadas com β-Lap (CM-β-lap-PEG-AuNRs). Nosso principal objetivo foi desenvolver um sistema multifuncional especifico para tratamento de câncer utilizando os antígenos e propriedades únicas da membrana das células cancerígenas combinados com as propriedades fototérmicas dos AuNRs e a atividade anticancerígena da β-Lap. Os resultados confirmaram o agrupamento dos PEG-AuNRs dentro das CM e irradiação com o laser no NIR levou ao rompimento das vesículas e liberação dos AuNRs e β-Lap. Estudos in vitro revelaram uma elevada e sinérgica citotoxicidade contra células A549, que pode ser atribuída a combinação da especifica toxicidade da β-Lap com o calor gerado pelos AuNRs por meio da irradiação com laser. Nenhuma citotoxicidade significativa foi observada na ausência de irradiação com laser. No segundo sistema, nanomatryoshkas de Au ativas em MRI foram desenvolvidas. Elas consistem em um núcleo de Au, uma camada intersticial de sílica, onde os íons de Gd(III) são encapsulados, e uma camada externa de Au (Gd-NM). Esta nanopartícula teranóstica mantém as propriedades de elevada absorção óptica no NIR, enquanto simultaneamente fornece um elevado contraste T1 em imagem por ressonância magnética por meio da concentração dos íons de Gd(III) dentro da nanoparticula. Medidas de Gd-NM revelaram uma relaxividade elevada (r1 ~ 17 mM-1 s-1 ) a 4,7 T, superando os convencionais agentes quelantes de Gd(III)-DOTA (r1 ~ 4 mM-1 s-1) utilizados clinicamente. As relaxividades observadas são consistentes com a teoria Solomon-Bloembergen-Morgan (SBM), descrevendo as interações de longo alcance entre Gd(III) e prótons de H fora da partícula. Os novos sistemas multifuncionais desenvolvidos abrem oportunidades para o desenvolvimento de nanoplataformas mais eficientes para o diagnóstico e tratamento de câncer.

Two types of 3-dimensional (3D) Ag nanosponge aggregates were prepared and tested as samples for surface-enhanced Raman scattering (SERS) and as active surfaces for surface- enhanced luminescence. 3D Ag nanosponge aggregates were assembled from 2D fused fractal aggregates (D = 1.87 ± 0.02) prepared by modification of Ag nanoparticle (NP) hydrosol resulting from the reduction of AgNO3 by NH2OH·HCl. For SERS measurements, 3D Ag nanosponge aggregates with incorporated [Ru(bpy)3]2+ cations and chloride anions were prepared and overlayed by a thin layer of aqueous phase. For SEL measurements, the 3D Ag nanosponge aggregates were assembled from fused fractal aggregates of chloride- modified Ag NPs. After preparation the active surface was overlayed by a 1×10-5 M aqueous solution of [Ru(bpy)3]2+ . The SERRS (1×10-15 M) and SER(R)S (1×10-14 M) limits of detection of [Ru(bpy)3]2+ determined at 445 and 532 nm excitations, respectively, correspond to the single molecule level of the complex detection. Its achievement is attributed to a large electromagnetic mechanism enhancement experienced by [Ru(bpy)3]2+ incorporated in "hot spots", an efficient localization of "hot spots" in the 3D aggregate to the focus of the laser beam in micro-Raman spectral measurements and to a molecular resonance contribution to the...

Doctor of Philosophy / Department of Chemistry / Viktor Chikan / This dissertation reports the colloidal synthesis of iron silicide, hafnium oxide core-gold shell and water soluble iron-gold alloy for the first time. As the first part of the experimentation, plasmonic and superparamagnetic nanoparticles of gold and iron are synthesized in the form of core-shell and alloy. The purpose of making these nanoparticles is that the core-shell and alloy nanoparticles exhibit enhanced properties and new functionality due to close proximity of two functionally different components. The synthesis of core-shell and alloy nanoparticles is of special interest for possible application towards magnetic hyperthermia, catalysis and drug delivery. The iron-gold core-shell nanoparticles prepared in the reverse micelles reflux in high boiling point solvent (diphenyl ether) in presence of oleic acid and oleyl amine results in the formation of monodisperse core-shell nanoparticles. The second part of the experimentation includes the preparation of water soluble iron-gold alloy nanoparticles. The alloy nanoparticles are prepared for the first time at relatively low temperature (110 oC). The use of hydrophilic ligand 3-mercapto-1-propane sulphonic acid ensures the aqueous solubility of the alloy nanoparticles. Next, hafnium oxide core-gold shell nanoparticles are prepared for the first time using high temperature reduction method. These nanoparticles are potentially important as a high κ material in semiconductor industry. Fourth, a new type of material called iron silicide is prepared in solution phase. The material has been prepared before but not in a colloidal solution. The Fe3Si obtained is superparamagnetic. Another phase β-FeSi2 is a low band gap (0.85 eV) semiconductor and is sustainable and environmentally friendly. At last, the iron monosilicide (FeSi) and β-FeSi2 are also prepared by heating iron-gold core-shell and alloy nanoparticles on silicon (111) substrate. The nucleation of gaseous silicon precursor on the melted nanoparticles results the formation of nanodomains of FeSi and β-FeSi2. A practical application of these nanoparticles is an important next step of this research. Further improvement in the synthesis of β-FeSi2 nanoparticles by colloidal synthetic approach and its application in solar cell is a future goal.

Nanopartículas (NPs) que apresentam ressonância plasmon de superfície localizada (RPSL) são aplicáveis em diversas áreas como, por exemplo, em terapia e diagnóstico na área biomédica. Estudos e aplicações in vivo requerem que a banda plasmon (BP) ocorra na mesma região da janela terapêutica, entre 600 e 1000 nm. Esta condição pode ser atingida com a modulação da BP pelo controle da morfologia e da composição química das NPs. Os objetivos principais deste trabalho foram estudar métodos de síntese que permitissem obter maiores quantidades de materiais quando comparados aos métodos convencionais em meio aquoso, e conjuntamente avaliar os parâmetros de síntese para obter NPs com diferentes morfologias e composições almejando modular a BP para região de interesse. Obteve-se nanoesferas (NEs) de Au monodispersas com diâmetro médio de 9 nm por redução com oleilamina em solução concentrada de sais de ouro. Dispersibilidade em água com elevada estabilidade coloidal foi alcançada via um procedimento de troca de ligantes, substituindo as moléculas de oleilamina, presentes na superfície das NPs assim como sintetizadas, por moléculas de ácido 11-mecaptoundecanóico. Nanobastões (NBs) de Au (largura de 12 nm) com diferentes comprimentos (30-300 nm) foram obtidos em misturas incomuns das fases cristalinas fcc e hcp. Estes NBs apresentam duas BP no espectro UV-Vis-NIR, uma em 520 nm e outra banda alargada a partir de 800 nm atribuídas à RPSL transversal e longitudinal, respectivamente. Inicialmente, os NBs foram sintetizados utilizando oleilamina como agente redutor e surfactante, sendo posteriormente avaliado que a presença de álcool oleico ou trietilamina no meio mantiveram uma condição de crescimento-1D mantendo a forma dos nanomateriais. NEs de Ag foram obtidas em condições semelhantes às NEs de Au com a BP em torno de 420 nm. Obteve-se misturas de NEs e NBs de AuCu3 (NBs, com razão de aspecto de 3) em todas as condições estudadas, sendo posteriormente separadas. Duas BP foram observadas para os NBs de AuCu3 em 560 e 766 nm, atribuídas à ressonância transversal e longitudinal, respectivamente. NPs monodispersas de Cu1,8S com 10 nm e BP centradas em 1150 nm foram sintetizadas por injeção a quente. Uma tentativa de recobrimento com Au das NPs de Cu1,8S resultou em uma reação de substituição, formando NPs de Au2S, a qual não apresentou BP. Investigou-se sínteses de NPs Cu1,8S dopado com M (M = Fe, Al e Zn) e alguns resultados foram: i) todas amostras foram obtidas na fase digenita e com baixa dispersão de tamanho; ii) Al e Fe incorporaram na estrutura cristalina, mas aparentemente o Zn não incorporou; iii) a BP foi deslocada para maiores comprimentos de ondas em todas amostras. Em resumo, obteve-se NPs com BP na região de interesse, em quantidades maiores que as sínteses convencionais. Este trabalho contribui para a compreensão da ação de reagentes/condições experimentais sobre a composição e o controle morfológico das NPs (principalmente crescimento-1D). Ressalta-se, entre os estudos, a formação de NBs de Au na fase hcp, possibilitando futuros estudos de propriedades; o redshift da BP das NPs de Cu1,8S dopados que não eram esperados, sendo um resultado instigante para futuros estudos; e a efetiva modificação de superfície das NPs de Au que resultou em elevada estabilidade coloidal na faixa de pH entre 6 e 10, possibilitando futuras aplicações. / Nanoparticles (NPs) that present localized surface plasmon resonance (LSPR) enables several applications, for example, therapy and diagnosis in the biomedical area. In vivo studies and applications require that plasmon band occurs in the same region of the therapeutic window, between 600 and 1000 nm. This condition can be achieved with the plasmon band (PB) modulation by morphological and chemical composition control of the NPs. The main purpose of this work concerning to evaluate of the syntheses parameters to obtain NPs with different morphologies and compositions by using experimental procedures, which to enable reach larger NPs amounts than the conventional aqueous medium methods. Monodisperse Au nanospheres (NSs) with average diameter of 9 nm were obtained by reduction of gold salts in concentrated solutions by oleylamine. As-synthesized Au-NSs present oleylamine molecules onto the surface that it was replaced by 11-mercaptoundecanoic acid by using a ligand exchange procedure, resulting in the water-dispersible system with high colloidal stability. Au nanorods (NRs, 12 nm-width) with different lengths (30-300 nm) were synthesized. These NRs are an expressive result, because its present an unusual fcc and hcp crystalline phases mixtures. There is only one paper in the literature that reports the direct synthesis of Au-hcp nanostructure. The NRs dispersion show two PB in the UV-Vis-NIR spectrum at 520 nm and another large band starting in 800 nm attributed to transversal and longitudinal LSPR, respectively. Initially, the NRs were synthetized by using oleylamine as reducing agent and surfactant, and NPs with same shape were obtained in presence of oleyl alcohol or triethylamine as surfactant in the medium. Ag NSs were obtained in similar conditions of Au NSs with shape control, and LSPR band in 420 nm. Mixtures of NSs and NRs (aspect ratio of 3) of AuCu3 were obtained for all studied conditions, and separated by using a selective separation process. Two PB were observed for AuCu3 NRs at 560 and 766 nm, assigned to transversal and longitudinal resonance, respectively. Monodisperse Cu1,8S semiconductor NSs with 10 nm and PB centered in 1150 nm were synthetized via hot-injection, and attempts to cover them with Au resulted in a substitution reaction that lead the formation of Au2S NPs, which did not present PB. Syntheses of M-doped Cu1,8S NPs (M = Fe, Al e Zn) were investigated and some results were: i) all samples are digenite phase and presented low dispersivity of size; ii) Al and Fe were incorporate more effective into the crystal structure than Zn; iii) were observed redshift of PB for all samples. In summary, NPs with PB in the region of interest were obtained in greater amounts than the conventional syntheses. This thesis presents contributions to the understanding of experimental parameters that act on the compositional and morphological control of NPs (mainly 1D growth). It is emphasized among the studies: the formation of Au NRs in the hcp phase, enabling future studies of properties; the PB redshift of the doped Cu1,8S NPs that were not expected, however, this is a stimulating result for future studies; and an effective surface modification of the Au NPs that result in high colloidal stability in the pH range between 6 and 10, allowing for future applications.

Nanopartículas (NPs) que apresentam ressonância plasmon de superfície localizada (RPSL) são aplicáveis em diversas áreas como, por exemplo, em terapia e diagnóstico na área biomédica. Estudos e aplicações in vivo requerem que a banda plasmon (BP) ocorra na mesma região da janela terapêutica, entre 600 e 1000 nm. Esta condição pode ser atingida com a modulação da BP pelo controle da morfologia e da composição química das NPs. Os objetivos principais deste trabalho foram estudar métodos de síntese que permitissem obter maiores quantidades de materiais quando comparados aos métodos convencionais em meio aquoso, e conjuntamente avaliar os parâmetros de síntese para obter NPs com diferentes morfologias e composições almejando modular a BP para região de interesse. Obteve-se nanoesferas (NEs) de Au monodispersas com diâmetro médio de 9 nm por redução com oleilamina em solução concentrada de sais de ouro. Dispersibilidade em água com elevada estabilidade coloidal foi alcançada via um procedimento de troca de ligantes, substituindo as moléculas de oleilamina, presentes na superfície das NPs assim como sintetizadas, por moléculas de ácido 11-mecaptoundecanóico. Nanobastões (NBs) de Au (largura de 12 nm) com diferentes comprimentos (30-300 nm) foram obtidos em misturas incomuns das fases cristalinas fcc e hcp. Estes NBs apresentam duas BP no espectro UV-Vis-NIR, uma em 520 nm e outra banda alargada a partir de 800 nm atribuídas à RPSL transversal e longitudinal, respectivamente. Inicialmente, os NBs foram sintetizados utilizando oleilamina como agente redutor e surfactante, sendo posteriormente avaliado que a presença de álcool oleico ou trietilamina no meio mantiveram uma condição de crescimento-1D mantendo a forma dos nanomateriais. NEs de Ag foram obtidas em condições semelhantes às NEs de Au com a BP em torno de 420 nm. Obteve-se misturas de NEs e NBs de AuCu3 (NBs, com razão de aspecto de 3) em todas as condições estudadas, sendo posteriormente separadas. Duas BP foram observadas para os NBs de AuCu3 em 560 e 766 nm, atribuídas à ressonância transversal e longitudinal, respectivamente. NPs monodispersas de Cu1,8S com 10 nm e BP centradas em 1150 nm foram sintetizadas por injeção a quente. Uma tentativa de recobrimento com Au das NPs de Cu1,8S resultou em uma reação de substituição, formando NPs de Au2S, a qual não apresentou BP. Investigou-se sínteses de NPs Cu1,8S dopado com M (M = Fe, Al e Zn) e alguns resultados foram: i) todas amostras foram obtidas na fase digenita e com baixa dispersão de tamanho; ii) Al e Fe incorporaram na estrutura cristalina, mas aparentemente o Zn não incorporou; iii) a BP foi deslocada para maiores comprimentos de ondas em todas amostras. Em resumo, obteve-se NPs com BP na região de interesse, em quantidades maiores que as sínteses convencionais. Este trabalho contribui para a compreensão da ação de reagentes/condições experimentais sobre a composição e o controle morfológico das NPs (principalmente crescimento-1D). Ressalta-se, entre os estudos, a formação de NBs de Au na fase hcp, possibilitando futuros estudos de propriedades; o redshift da BP das NPs de Cu1,8S dopados que não eram esperados, sendo um resultado instigante para futuros estudos; e a efetiva modificação de superfície das NPs de Au que resultou em elevada estabilidade coloidal na faixa de pH entre 6 e 10, possibilitando futuras aplicações. / Nanoparticles (NPs) that present localized surface plasmon resonance (LSPR) enables several applications, for example, therapy and diagnosis in the biomedical area. In vivo studies and applications require that plasmon band occurs in the same region of the therapeutic window, between 600 and 1000 nm. This condition can be achieved with the plasmon band (PB) modulation by morphological and chemical composition control of the NPs. The main purpose of this work concerning to evaluate of the syntheses parameters to obtain NPs with different morphologies and compositions by using experimental procedures, which to enable reach larger NPs amounts than the conventional aqueous medium methods. Monodisperse Au nanospheres (NSs) with average diameter of 9 nm were obtained by reduction of gold salts in concentrated solutions by oleylamine. As-synthesized Au-NSs present oleylamine molecules onto the surface that it was replaced by 11-mercaptoundecanoic acid by using a ligand exchange procedure, resulting in the water-dispersible system with high colloidal stability. Au nanorods (NRs, 12 nm-width) with different lengths (30-300 nm) were synthesized. These NRs are an expressive result, because its present an unusual fcc and hcp crystalline phases mixtures. There is only one paper in the literature that reports the direct synthesis of Au-hcp nanostructure. The NRs dispersion show two PB in the UV-Vis-NIR spectrum at 520 nm and another large band starting in 800 nm attributed to transversal and longitudinal LSPR, respectively. Initially, the NRs were synthetized by using oleylamine as reducing agent and surfactant, and NPs with same shape were obtained in presence of oleyl alcohol or triethylamine as surfactant in the medium. Ag NSs were obtained in similar conditions of Au NSs with shape control, and LSPR band in 420 nm. Mixtures of NSs and NRs (aspect ratio of 3) of AuCu3 were obtained for all studied conditions, and separated by using a selective separation process. Two PB were observed for AuCu3 NRs at 560 and 766 nm, assigned to transversal and longitudinal resonance, respectively. Monodisperse Cu1,8S semiconductor NSs with 10 nm and PB centered in 1150 nm were synthetized via hot-injection, and attempts to cover them with Au resulted in a substitution reaction that lead the formation of Au2S NPs, which did not present PB. Syntheses of M-doped Cu1,8S NPs (M = Fe, Al e Zn) were investigated and some results were: i) all samples are digenite phase and presented low dispersivity of size; ii) Al and Fe were incorporate more effective into the crystal structure than Zn; iii) were observed redshift of PB for all samples. In summary, NPs with PB in the region of interest were obtained in greater amounts than the conventional syntheses. This thesis presents contributions to the understanding of experimental parameters that act on the compositional and morphological control of NPs (mainly 1D growth). It is emphasized among the studies: the formation of Au NRs in the hcp phase, enabling future studies of properties; the PB redshift of the doped Cu1,8S NPs that were not expected, however, this is a stimulating result for future studies; and an effective surface modification of the Au NPs that result in high colloidal stability in the pH range between 6 and 10, allowing for future applications.

The presented diploma thesis is focused on finding conditions suitable for the study of surface reactions, especially Suzuki-Miyaura cross-coupling reaction (SMCR), by the surface- enhanced Raman scattering (SERS) method. The first part of the work deals with the optimization of the conditions of individual reactions using the classical synthetic Schlenk technique. Traditional, published, conditions for SMCR were gradually modified during the work so that the reactions could be performed in aqueous media and at room temperature, i.e., under conditions suitable for SERS spectroscopy. The following catalysts were tested: (i) PEPPSI - the traditional SMCR catalyst; (ii) palladium ions; (iii) Pd colloids; (iv) bimetallic colloids of Pd and plasmonic metal (Ag, Au) in the form of core-shell and alloy; (v) Ag and Au colloids with additions of palladium salt or N- heterocyclic carbenes (NHC-catalysts). Two groups of substrates were used: substrates with functional groups with high affinity for the surfaces of metal nanoparticles (NPs) and substrates without these anchoring functional groups. Substrates without the anchoring functional groups can be expected to enter the SMCR reaction from solution. In the second part of this diploma thesis selected reaction mixtures for SMCR were performed in septum...

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[ES] La irradiación de nanopartículas de oro (AuNPs) esféricas en una suspensión coloidal con pulsos láser de nanosegundos puede inducir su metamorfosis, dando lugar a la aparición de esferas con cavidades internas. La concentración del surfactante estabilizador de las partículas, el uso de fluencias de láser moderadas y el tamaño de las partículas, determinan la eficiencia y características del proceso. Las partículas huecas resultantes se obtienen cuando las moléculas del medio circundante (ej., agua, materia orgánica del surfactante) quedan atrapadas durante la irradiación láser. Estas observaciones experimentales sugieren la existencia de un balance sutil entre los procesos de calentamiento y enfriamiento. El primero induce la expansión y paso a un estado amorfo y, el segundo, la subsecuente recristalización manteniendo en su interior el material atrapado. Estas observaciones experimentales han sido explicadas satisfactoriamente con las simulaciones de dinámica molecular clásica desarrolladas en el marco de esta tesis. Específicamente, la dinámica molecular confirma que es necesaria la existencia de moléculas en el interior de las cavidades que se forman dentro de las AuNPs para que se produzca su estabilización. En la segunda parte de esta tesis, se detallan las simulaciones de dinámica molecular clásica y los cálculos de propiedades ópticas de la irradiación de nanopartículas esféricas de oro con pulsos láser de femtosegundos, para predecir los cambios de forma que se producen en las mismas, bajo una exploración de los diferentes parámetros involucrados, es decir, la fluencia y duración del láser, el tamaño de las nanopartículas cristalinas esféricas y la capacidad de enfriamiento del medio circundante. El objetivo fundamental de las simulaciones es brindar una guía para la síntesis de nanopartículas con morfologías determinadas. Los resultados de las simulaciones indican que, para la formación de nanopartículas huecas, las mismas deben ser calentadas hasta una temperatura entre 2500 y 3500 K, seguido por un enfriamiento exponencial rápido, con una constante de tiempo menor de 120 ps. Por lo tanto, se describen las condiciones experimentales para la producción eficiente de nanopartículas huecas, lo que abre un amplio rango de posibilidades de aplicación en áreas fundamentales, tales como el almacenamiento de energía y la catálisis. En la última parte de esta memoria se exponen las simulaciones de dinámica molecular clásica implementadas para profundizar en los experimentos pumpprobe con nanoesferas plasmónicas de oro, desarrollados en la referencia [R.Fuentes-Domínguez et al. Appl. Sci. 2017, 7(8), 819.]. Tras la irradiación láser y consecuente deposición de energía, las partículas vibran, lo que se puede medir mediante la fuerte modulación producida en la sección eficaz de dispersión. La vibración mecánica de las AuNPs esféricas, tras ser irradiadas con láseres ultracortos, las convierte en generadores termoelásticos eficientes de ultrasonido y, por tanto, en excelentes candidatos para transductores luz-sonido en diversas aplicaciones. / [CA] La irradiació de nanopartícules d'or (AuNPs) esfèriques en una suspensiócolloidal amb polsos làser de nanosegons pot induir la seua metamorfosi, donant lloc a l'aparició d'esferes amb cavitats internes. La concentració del surfactante estabilitzador de les partícules, l'ús de fluencias de làser moderades i la grandària de les partícules, determinen l'eficiència i característiques del procés. Les partícules buides resultants s'obtenen quan les molècules del mitjà circumdant (ex., aigua, matèria orgànica del surfactante) queden atrapades durant la irradiació làser. Aquestes observacions experimentals suggereixen l'existència d'un balanç subtil entre els processos de calfament i refredament. El primer indueix l'expansió i passe a un estat amorf i, el segon, la subseqüent recristalización mantenint en el seu interior el material atrapat. Aquestes observacions experimentals han sigut explicades satisfactòriament amb les simulacions de dinàmica molecular clàssica desenvolupades en el marc d'aquesta tesi. Específicament, la dinàmica molecular confirma que és necessària l'existència de molècules a l'interior de les cavitats que es formen dins de les AuNPs perquè es produïsca la seua estabilització. En la segona part d'aquesta tesi, es detallen les simulacions de dinàmica molecular clàssica i els càlculs de propietats òptiques de la irradiació de nanopartícules esfèriques d'or amb polsos làser de femtosegundos, per a predir els canvis de manera que es produeixen en aquestes, sota una exploració dels diferents paràmetres involucrats, és a dir, la fluencia i duració del làser, la grandària de les nanopartícules cristal·lines esfèriques i la capacitat de refredament del mitjà circumdant. L'objectiu fonamental de les simulacions és brindar una guia per a la síntesi de nanopartícules amb morfologies determinades. Els resultats de les simulacions indiquen que, per a la formació de nanopartícules buides, les mateixes han de ser calfades fins a una temperatura entre 2500 i 3500 K, seguit per un refredament exponencial ràpid, amb una constant de temps menor de 120 pg. Per tant, es descriuen les condicions experimentals per a la producció eficient de nanopartícules buides, la qual cosa obri un ampli rang de possibilitats d'aplicació en àrees fonamentals, tals com l'emmagatzematge d'energia i la catàlisi. En l'última part d'aquesta memòria s'exposen les simulacions de dinàmica molecular clàssica implementades per a aprofundir en els experiments pumpprobe amb nanoesferas plasmónicas d'or, desenvolupats en la referència [R. Fuentes-Domínguez et al. Appl. Sci. 2017, 7(8), 819.]. Després de la irradiació làser i conseqüent deposició d'energia, les partícules vibren, la qual cosa es pot mesurar mitjançant la forta modulació produïda en la secció eficaç de dispersió. La vibració mecànica de les AuNPs esfèriques, després de ser irradiades amb làsers ultracortos, les converteix en generadors termoelásticos eficients d'ultrasò i, per tant, en excel·lents candidats per a transductors llum-so en diverses aplicacions. / [EN] The irradiation of gold nanoparticles (AuNPs) in a colloid with nanosecond laser pulses can give rise to the formation of cavities. The concentration of the surfactant used to stabilize the particles, the laser fluency, and the size of the nanoparticles, determine the efficiency and features of the process. The resulting hollow particles are obtained when the right balance between the heating and cooling processes is given. The first process induces an expansion and the melting of the particle, while the second, leads to the recrystallization, keeping the extraneous matter trapped in the inside. These experimental observations have been satisfactorily explained by the molecular dynamics simulations carried out in this thesis. Specifically, the simulations have confirmed that it is necessary the existence of trapped molecules in the inside of the cavities to stabilize the cavities. In the second part of this thesis, the molecular dynamics simulations and calculation of optical properties when gold nanoparticles (in a colloid) are irradiated with femtosecond laser pulses. The simulations allowed to predict the the shape changes under different conditions for the laser fluency and duration, the size of the nanoparticles and the cooling rate, which is driven by the properties of the solvent and the surfactant. These simulations provide a guidance for the synthesis of nanoparticles with specific morphological features. The results show that the nanospheres should be heated up to 2500 y 3500 K, followed by a fast cooling (time constant of 120 ps). Therefore, the experimental conditions for the efficient production of hollow nanoparticles are described what opens a broad range of possibilities for applications in areas such as energy storage and catalysis. MD simulations are carried out in the last part of this thesis to gain insights into the pump-probe experiments using AuNPs in reference [R. Fuentes-Domínguez et al. Appl. Sci. 2017, 7(8), 819.]. Upon femtosecond laser irradiation and deposition of energy, the nanospheres vibrate which can be measured by means of the scattering cross section. This fact becomes the AuNPs in ideal thermoelastic ultrasound generators and therefore in excellent candidates for light-sound transducers in different applications. / Castro Palacio, JC. (2021). Modelación físico-matemática y simulaciones computacionales para guiar el diseño y fabricación de nanoestructuras plasmónicas optimizadas para aplicaciones energéticas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/175557 / TESIS

This work is aimed at the preparation and morphological and spectroscopic characterization of the interphase nanocomposite (NC) two-dimensional (2D) self-assembled systems of Ag and Au nanoparticles (NPs). The NPs were functionalized with the following ligands with terpyridine end-groups: 2,2′:6′,2′′-terpyridine (tpy), 4'-(2-thienyl)-2,2':6',2''- terpyridine (T-tpy), α,ω-bis(terpyridyl)-2,2'-bithiophene (tpy-2T-tpy) and α,ω-bis(terpyridyl)- 2,2':5',2''-terthiophene (tpy-3T-tpy). The morphological analysis of transmission electron micrographs proves the preservation of the average interparticle distance in closely spaced NP pairs, independent of the ligand. The value of the total average interparticle distance increases in the order: tpy < T-tpy < tpy- 2T-tpy < tpy-3T-tpy, while the average occupied area fraction in the same order decreases. The morphological descriptors (i.e. interparticle distance and occupied area fraction) were found to correlate with the shift of the SPE (surface plasmon extinction) maxima of NCs (tpy > T-tpy > tpy-2T-tpy > tpy-3T-tpy). The results show that the shift of SPE band maximum depends on the degree of surface plasmon delocalisation rather than on the value of the average interparticle distance in closely spaced NP pairs. The smaller are the islands formed by closely...

In the first part of the Thesis, a new type of active system for SERS and SERRS of hydrophobic molecules, namely a 3-dimensional (3D) nanosponge aggregate with incorporated hydrophobic molecules has been developed, and tested by fullerene C60 and hydrophobic free- base tetraphenylporfine (H2TPP). The SERS and SERRS (surface enhanced /resonance/ Raman scattering) limits of detection (LODs) of C60 at four excitation wavelengths spanning the visible spectral region were found to be by one order of magnitude lower than in the reference system, which mimics the previously reported ways of utilization of Ag nanosponges as substrates for SERS and SERRS. The superiority of the newly developed sample is attributed to the efficient localization of the hydrophobic molecules into hot spots in 2D fractal aggregates of Ag nanoparticles (NPs). Diprotonation of H2TPP during the procedure using HCl as the preaggregation agent has been eliminated by employment of NaCl. On the other hand, investigation of the mechanism of H2TPP protonation during the former preparation procedure opened a possibility to employ Ag nanosponge aggregate as nanoreactor. In the second part of the Thesis, 2D assemblies of AgNPs were found to be better substrates for SERS of single layer graphene (SLG) than the 3D ones. In particular, the 2D...