The thesis entitled “Local structure-property relationship in some selected Solid State Materials” mainly focuses on two fundamental topics: (a) evaluation of some standard global structural concepts in terms of local structure to provide a unique description of the crystal structure, and (b) the role of the crystal structure at different length-scales in controlling the properties in some selected materials.

This thesis reports a passive method for Fermi level regulation in quantum dot assemblies through ground state transfer between QDs. Here, ZnTe/CdS, and PbSe/CdSe core/shell QDs were used as valence band electron donors, while Cu containing CdS or ZnSe acts as electron acceptor QDs. Prior to study of ground state charge transfer process, this report discusses the synthesis of ZnTe/CdS, and PbSe/CdSe core shell QDs, which are later used to study charge transfer. Since ZnTe QDs are unstable and prone to oxidation, a CdS coated ZnTe QDs were used. Growing a CdS shell on ZnTe core is difficult because high reduction potential of Te. To overcome this problem, partially reduced sulphur is used for the synthesis of ZnTe/CdS. The peculiar optical properties exhibited by ZnTe/CdS also have been discussed. Even though the synthesis of Lead chalcogenide nanoparticles has been investigated previously, certain inconsistencies between the behavior expected from known mechanisms and empirical observations. An anion exchange mechanism is proposed and demonstrated to be involved in PbSe formation. Both ZnTe and PbSe based QDs are extensively used to study hole injection and copper containing QDs were used as acceptors. The charge transfer has been studied using optical spectroscopy. The structure and composition of the assemblies was identified using powder crystallography, electron-microscopy and composition analysis. The unique physical and chemical properties of these materials are exciting both fundamentally as well as from the point of view of applications.

This thesis reports the successful rational design of three highly active photocatalytic semiconductor nanocrystal (SNC) systems by exploiting morphology effects and the electronic properties of type II semiconductor heterojunctions. Novel architectures of colloidal SNCs are produced with the aim of suppressing exciton recombination and improving charge extraction for the successful initiation of desirable redox chemistry. Rod-shaped niobium pentoxide Nb₂O₅ nanocrystals (NCs) are shown to exhibit significantly enhanced activity (10-fold increase in rate constant) relative to spherical-shaped NCs of the same material. The increase is attributed to Nb5⁺ Lewis acid site rich (001) surfaces, present in higher proportions in the rod morphology, which bind organic substrates from solution resulting in direct interaction with photogenerated charges on the surface of the NC. Building on the insights into morphology-activity dependence, type II semiconductor heterojunctions are exploited for their ability to increase exciton lifetimes and spatially separate charges. Two novel II-VI heterostructured semiconductor nanocrystals (HSNCs) systems are investigated: a series of CdX/ZnO (X = S, Se, Te) HSNCs and ZnS/ZnO HSNCs capped with two different surface ligands. In the first case, substantial photocatalytic activity improvement is observed for HSNCs (relative to pure ZnO analogues) according to the following trend: CdTe/ZnO > CdS/ZnO > CdSe/ZnO. The observed trend is explained in terms of heterojunction structure and fundamental chalcogenide chemistry. In the second case, both ZnS/ZnO HSNCs exhibit activity enhancement over analogous pure ZnO, but the degree of enhancement is found to be a function of surface ligand chemistry. Photocatalytic activity testing of all the materials investigated in this work is performed via the photodecomposition of methylene blue dye in aerated aqueous conditions under UVA (350 nm) irradiation. The synthetic techniques employed for the synthesis of colloidal SNCs investigated in this thesis range from chemical precipitation and solvothermal techniques to several different organometallic approaches. A wide variety of analytical techniques are employed for the chemical, structural and optical characterisation of SNC photocatalysts including: XRD, XPS, TEM, UV-vis absorption, PL spectroscopy and FTIR. Atom Probe Tomography (APT) is employed for the first time in the structural characterisation of II-VI heterojunctions in colloidal HSNCs. Overall, this thesis provides a useful contribution to the growing body of knowledge pertaining to the enhancement of photocatalytic SNCs for useful applications including: solar energy conversion to chemical fuels, the photodecomposition of pollutants and light-driven synthetic chemistry.

Featuring size-tunable electrical and optical properties, semiconductor nanocrystals (NCs) attract intensive interest in developing promising functional materials for optoelectronic appli-cations. The surface ligands not only play an important role in the synthesis and colloidal sta-bility of NCs, but also significantly affect their photophysical and electrochemical properties. In this dissertation, I am dealing with the surface ligand engineering of NCs (including both perovskite and metal chalcogenide families) for optical and photocatalytic applications. Polymer ligands are regarded to enable better colloidal stability, durability and processability of fluorescent NCs, which is especially important for perovskite NCs. However, the current wide-used polymer ligands fail to provide sufficient surface passivation for the NCs, which is unfavorable for their luminescence. To address this issue, a dual-ligand system based on par-tially hydrolyzed poly(methyl methacrylate) (h-PMMA) and highly branched polyethyl-enimine (PEI) was designed to stabilize perovskite NCs. The hydrophobic polymer of h-PMMA imparts excellent film-forming properties and durability to the resulting NC-polymer composite. The PEI forms an amino-rich, strongly binding ligand layer on the surface of the NCs being responsible for the significant improvement of the photoluminescence quantum yield and the stability of the resulting material. These superior properties allowed us to fabri-cate a proof-of-concept thin film organic light-emitting diode (OLED) with h-PMMA/PEI-stabilized perovskite NCs. A further insight into the roles of double polymer ligands (h-PMMA and PEI) during the mechanosynthesis of perovskites nanoparticles (NPs) was pro-vided. The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs. The PEI with large amounts of amino groups induced enrichment of PbBr2 in the reaction mixture, which in turn caused the formation of heterostructured CsPbBr3-CsPb2Br5-mPbBr2 and CsPbBr3-Cs4PbBr6-nCsBr NPs. Not only polymer, but also inorganic ligands can be extremely attractive for capping of NCs. In the frame of this thesis, a two-step surface modification strategy was developed to control-lably destabilize the colloidal NCs, which in turn facilitated their 3D assembly into aerogels. Specifically, the long-chain oleic acid ligands were exchanged to the ultra-short-chain inorganic (NH4)2S ligands. These new ligands were further protonated by changing the dispersing solvent, which caused desired colloidal destabilization. The as-prepared CdSe NC aerogels with highly porous and self-supporting structure were found to be attractive for solid-state photocatalysis in a gas phase. Indeed, the (NH4)2S ligand is favourable for the adsorption and activation of substrate molecules (i.e., H2O and CO2) on the large open surface of NC gel, thereby promoting the progress of CO2 photoreduction. As a result, the photocatalytic activity for CO2 reduction of CdSe NC aerogels created in this work is 12-fold higher than that of the pristine non-assembled NC-precipitates.:Abstract 1 Contents 3 Abbreviations 6 List of Figures and Tables 8 1. Colloidal Semiconductor Nanocrystals and their Ligand Shell 13 1.1. Colloidal Semiconductor Nanocrystals 14 1.1.1. Inorganic Core of NCs 15 1.1.1.1. Metal Chalcogenide NCs 16 1.1.1.2. Metal Pnictide NCs 16 1.1.1.3. Halide Perovskites NCs 17 1.1.2. The Surface Ligands for NCs 18 1.1.2.1. The Classification of Surface Ligands based on Head-Groups 18 1.1.2.2. The Classification of Surface Ligands based on Tail-Groups 19 1.2. The Role of Ligands 20 1.2.1. The Role of Ligands in the Synthesis of NCs 20 1.2.2. The Role of Ligand in Colloidal NCs Dispersion and Stability 22 1.2.3. The Role of Ligand in the Light-Matter Interactions as Applied to NCs 24 1.3. The Surface Ligand Engineering of NCs 26 1.3.1. Introducing Ligands during the Synthesis 26 1.3.2. Introducing the Ligands during Post-Synthesis Process 27 1.4. Challenges to be Addressed in this Dissertation 29 2. Polymer Ligands Enhance the Stability and Fluorescence of Perovskite for Optical Application 31 2.1. Background and Motivation 32 2.2. Results and Discussion 34 2.2.1. Spectral Characterization 34 2.2.2. Morphological Characterization 40 2.2.3. Surface Composition 41 2.2.4. Processability, Stability and Durability 43 2.2.5. Green-LED 46 2.3. Conclusions 48 3. Polymer Ligands Assist Mechanosynthesis of Perovskite Nanoparticles 49 3.1. Background and Motivation 50 3.2. Results and Discussion 50 3.2.1 Morphology and Composition 51 3.2.2 Formation and Phase Conversion of the Nanoparticles 53 3.2.3. Spectral Characterization 58 3.3. Conclusions 60 4. Ligand Protonation Promote 3D Assembly of CdSe Nanocrystals for CO2 Photoreduction 62 4.1. Background and Motivation 63 4.2. Results and Discussion 64 4.2.1. The Gelation Method 64 4.2.2. Surface Composition of the NC Aerogels 67 4.2.3. Performance of CdSe-S Aerogels in Photoreduction of CO2 68 4.2.4. Photocatalytic Mechanism of the CdSe-S/Ni Aerogel 70 4.3. Conclusion 73 5. Conclusions and Perspectives 75 Appendix. Experimental Section 78 A.1. Reagents 78 A.2. NCs synthesis 78 A.2.1 Mechanosynthesis of Polymer-Coordinated Perovskite NCs 78 A.2.2 Oil Phase Synthesis of Colloidal CdSe NCs 79 A.2.3 Ligand Protonation-Promoted Assembly of CdSe-S NCs into Gel 79 A.3. Optical and Photocatalytic Applications of NCs 80 A.3.1 Optical Applications of Polymer-Stabilized Perovskite NCs 80 A.3.2 Photocatalytic Applications of CdSe-S Aerogels 80 A.4. Characterization Methods 81 A.4.1 Morphology Characterization 81 A.4.2.Element Characterization 81 A.4.3 Diffraction Characterization 82 A.4.4 Spectroscopy Characterization 82 A.4.5 Gas adsorption Measurement 82 A.4.6 Electrochemical Measurements 83 A.4.7 Other Characterizations 83 A.5. Additional Data 84 Bibliography 87 List of Publications 96 Acknowledgements 98 Erklärung 100

The objective of this research is to develop a water-based processing method for incorporating large filler loadings into nanocomposite systems. Specifically, cellulose nanocrystal/poly(vinyl alcohol) (CNC/PVA) nanocomposite aqueous suspensions and films were processed and characterized at CNC loadings up to 67 wt.% with respect to polymer concentration. Both aqueous suspended and freeze-dried CNCs were studied with this method. Two methods for incorporating the CNCs were investigated: solution processing and batch mixing of aqueous suspensions. The materials produced by these methods were characterized using rheology of aqueous suspensions and a method for understanding the morphology of these aqueous suspension through rheological characterization was developed. The CNC/PVA suspensions were dried and the structure of the film studied using x-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. With regard to characterization of polymer structure by these methods, PVA crystallinity was seen to increase with increasing CNC loading. Finally, dynamic mechanical analysis and micro-tensile testing were conducted on consolidated films and CNCs were seen to increase modulus, yield stress but decrease strain at failure. Biodegradation studies were also conducted and CNCs were seen to increase the biodegradation characteristics of PVA. While the general trends in experimental data were the same, differences in properties between systems made with solution processing and batch mixing were observed, attributed to differences in the CNC dispersion. Overall, results indicated that this methodology is feasible for the industrially scalable production of highly loaded nanocomposites.

Nanocrystalline cerium oxide thin films on metal and semiconductor substrates have been fabricated with a novel electrodeposition approach - anodic oxidation. X-ray diffraction analysis indicated that as-produced cerium oxide films are characteristic face-centered cubic fluorite structure with 5 ~ 20 nm crystal sizes. X-ray photoelectron spectroscopy study probes the non-stoichiometry property of as-produced films. Raman spectroscopy and Scanning Electron Microscopy have been applied to analyze the films as well. Deposition mode, current density, reaction temperature and pH have also been investigated and the deposition condition has been optimized for preferred oriented film formation: galvanostatic deposition with current density of -0.06 mA/cm2, T > 50oC and 7 < pH < 10. Generally, potentiostatic deposition results in random structured cerium oxide films. Sintering of potentiostatic deposited cerium oxide films leads to crystal growth and reach nearly full density at 1100oC. It is demonstrated that in-air heating favors the 1:2 stoichiometry of CeO2. Nanocrystalline cerium oxide powders (4 ~ 10 nm) have been produced with anodic electrochemical synthesis. X-ray diffraction and Raman spectroscopy were employed to investigate lattice expansion phenomenon related to the nanoscale cerium oxide particles. The pH of reaction solution plays an important role in electrochemical synthesis of cerium oxide films and powder. Cyclic voltammetry and rotation disk electrode voltammetry have been used to study the reaction mechanisms. The results indicate that the film deposition and powder formation follow different reaction schemes. Ce(III)-L complexation is a reversible process, Ce3+ at medium basic pH region (7~10) is electrochemically oxidized to and then CeO2 film is deposited on the substrate. CE mechanism is suggested to be involved in the formation of films, free Ce3+ species is coordinated with OH- at high basic pH region (>10) to Ce2O3 immediately prior to electrochemically oxidation Ce2O3 to CeO2. CeO2 / montmorillonite nanocomposites were electrochemically produced. X-ray diffraction and Raman spectroscopy illustrate the retaining of FCC structure for cerium oxide. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry of composites indicate the insertion of montmorillonite platelets into the structural matrix of cerium oxide. Sintering study of the nanocomposites demonstrates that low concentration of montmorillonite platelet coordination into cerium oxide matrix increases crystal growth rate whereas high concentration of montmoillonite in nanocomposites retards the increase of crystallite size during the densification process.

Il y a des indications que les nanocristaux de silicium (nc-Si) présentent un gain optique qui est potentiellement assez grand pour permettre l'amplification optique dans la gamme de longueurs d'ondes où une photoluminescence (PL) intense est mesurée (600- 1000 nm). Afin de fabriquer des cavités optiques, nous avons implantés des morceaux de silice fondue avec des ions de Si pour former une couche de nc-Si d'une épaisseur d'environ 1 μm. Le Si a été implanté à quatre énergies comprises entre 1 MeV et 1,9 MeV de manière à obtenir une concentration atomique de Si en excès variant entre 25% et 30%. Les pièces ont été flanquées de miroirs diélectriques composés de filtres interférentiels multicouches. Sur une plage de longueurs d'ondes d'environ 200 nm de large, un filtre réfléchit près de 100%, alors que l'autre a une réflexion moyenne d'environ 90%. Nous avons mesuré et comparé les spectres de PL de trois échantillons: le premier sans miroir, le second avec des filtres réfléchissant autour de 765 nm (entre 700 nm et 830 nm), et la troisième avec des filtres agissant autour de 875 nm (entre 810 nm et 940 nm). Lorsque les échantillons sont excités avec un laser pulsé à 390 nm, des mesures de photoluminescence résolue dans le temps (PLT) révèlent des taux de décroissance plus rapides en présence de miroirs dans le domaine de longueurs d'onde où ceux-ci agissent comparé aux échantillons sans miroirs. Aussi, l'intensité PL en fonction de la fluence d'excitation montre une augmentation plus rapide de la présence de miroirs, même si celle-ci reste sous-linéaire. Nous concluons que de l'émission stimulée pourrait être présente dans la cavité optique, mais sans dominer les autres mécanismes d'émission et de pertes. / There are indications that silicon nanocrystals (nc-Si) exhibit an optical gain that is potentially large enough to enable optical amplification in the wavelength range where intense photoluminescence (PL) is measured (600-1000 nm). We fabricated optical cavities on fused silica pieces ion-implanted with Si in order to form a nc-Si layer with a thickness of about 1 μm. Si was implanted at four energies between 1 MeV and 1.9 MeV to obtain an excess atomic concentration varying between 25% and 30%. The pieces were sandwiched between dielectric mirrors consisting of multilayer interference filters. Over a wavelength range of about 200 nm wide, one filter reflects nearly 100%, while the other one shows an average reflection of 90%. We measured and compared the PL spectra of three samples: the first one with no mirrors, the second one with filters reflecting around 765 nm (between 700 nm and 830 nm), and the third one with filters acting around 875 nm (between 810 nm and 940 nm). When exciting the samples with a pulsed laser, timeresolved PL measurements exhibited faster decay rates in the wavelength domain where the reflection of the mirrors is maximal compared to samples without mirrors. Also, PL intensity as a function of excitation flux showed a faster increase in the presence of mirrors, although the increase remained sub-linear. From this, we conclude that stimulated emission could be present in the optical cavity, but does not dominate the other emission and loss processes.

To date, the search efforts have shifted from the toxic II-VI, III-V and IV-VI semiconductors to more environmentally friendly materials. Among Group II-V semiconductors, Zn3P2 has shown to be a more benign option, similar to Group IV (Ge, Si) materials, for future applications in photovoltaics and optoelectronics. This work is dedicated to the development of wet-chemical synthetic routes of (1) Zn3P2 and (2) Group IV (Ge, Si, Si1-xGex) nanocrystals with precise control over composition, crystal structure, size and dispersity by adjusting different reaction parameters such as temperature, time and solvent composition. Different characterizations will also be employed to probe the size- and composition-dependent physical and optical properties of resulting products. The first part of this work illustrates the synthesis of luminescent Zn3P2 nanocrystals, an earth-abundant and a direct-gap semiconductor possessing high absorption coefficient and long carrier diffusion length, which uphold promising potential in many optoelectronic applications. A hot injection method by using highly reactive P and Zn precursors (P[Si(CH3)3]3 and diethyl zinc) in hexadecylamine and octadecene was developed to prepare a series of alkyl-amine-passivated tetragonal Zn3P2 crystallites with varying size sizes. Substantial blue shifts in the absorption onsets (2.11−2.73 eV) in comparison to the bulk counterpart (1.4−1.5 eV) and a clear red shift with increasing particle size indicates the quantum confinement effects. This is also consistent with the photoluminescent studies with the size-tunable maxima in the visible region (469−545 nm) as a function of growth temperature and time. The phase purity and alkyl-amine passivation of the nanocrystals were determined by structural and surface analysis, confirming the presence of N–Zn and N–P bonds on the tetragonal Zn3P2 crystallites. The second part of this works focuses on the development of a colloidal synthetic strategy of alkyl-amine capped Si1-xGex nanocrystals with control over size- and composition-dependent optical properties. Despite their high miscibility at all compositions, developing a wet-chemical synthesis of Si1-xGex alloys in the nanoscale remains a challenging task, owing to the difference of their crystallization temperatures and the high surface oxidation of Si. Thus an adapted colloidal method is utilized to fabricate single-element Ge and Si nanocrystals. Powder X-ray diffraction indicates successful production of cubic crystalline Ge and amorphous Si nanoparticles individually in oleylamine/octadecene (surfactant/solvent) mixture at 300°C. Absorption onset values of 1.28 eV and 3.11 eV are obtained for resulting Ge and Si colloids, respectively. By alloying these two materials in their nano-regime, tunable optical properties can be achieved throughout the visible to the near IR region by simply varying their elemental compositions. The success of this bandgap engineering process offers more options for new material design by taking advantage of unique properties from each component material.

Segundo a Organização Mundial de Saúde, a hipertensão arterial é responsável por uma crise global de saúde pública, sendo as doenças cardiovasculares implicadas em aproximadamente 17 milhões de mortes/ano, das quais, 9,4 milhões ocasionadas por complicações provocadas pela hipertensão, como edema pulmonar. Quanto ao arsenal terapêutico disponível, a furosemida, potente diurético de alça, é amplamente utilizada em situações de controle e emergência relacionadas à hipertensão e ao edema pulmonar cardiogênico. Apesar do elevado índice de sua prescrição, esse fármaco pertence à classe IV do Sistema de Classificação Biofarmacêutica (SCB), apresentando absorções intestinais erráticas e variáveis. Tais características representam desafio para o desenvolvimento de formas farmacêuticas orais. Assim, adoção de tecnologias inovadoras associadas à via de administração pulmonar pode permitir abordagem terapêutica alternativa, com elevado potencial de aplicação. Entre as tecnologias inovadoras, a obtenção de nanocristais de fármacos classes II e IV tem sido promissora. Nanocristais podem exibir desempenho in vivo superior quando comparados aos seus homólogos, na forma micronizada. Portanto, estratégias que permitam o desenvolvimento de medicamentos contendo furosemida, com maior eficácia e segurança, são de fundamental importância. Nesse sentido, a aplicação de tecnologia in silico, com propriedade preditiva, contribui para a racionalização de ensaios na pesquisa e no desenvolvimento de novas formas farmacêuticas. Objetivou-se, desse modo, a preparação e a caracterização físico-química de nanocristais de furosemida e sua avaliação in silico na absorção oral e pulmonar empregando ferramenta computacional. Os nanocristais foram obtidos por moagem à alta energia, utilizando movimentos simultâneos de revolução/rotação. A determinação da distribuição do tamanho e a morfologia foram realizadas por difração de raios laser e microscopia eletrônica de varredura, respectivamente. As possíveis interações e/ou alterações do estado cristalino do fármaco foram investigadas por calorimetria exploratória diferencial, termogravimetria diferencial, difração de raio X e espectroscopia Raman de baixo deslocamento. Quanto à solubilidade do nanocristal, foram realizados ensaios para a determinação do aumento na solubilidade de equilíbrio e da velocidade dissolução, utilizando os métodos shake flask e velocidade de dissolução intrínseca (VDI), respectivamente. A moagem à alta energia permitiu a obtenção de nanocristais com tamanho médio trinta vezes menor (231nm) do que o tamanho inicial, na escala micrométrica (7,1 &#181;m). Os nanocristais apresentaram estabilidade térmica. Não foram observadas interações entre os excipientes e os nanocristais, que, entretanto, exibiram estrutura cristalina menos definida, o que indica parcial amorfização do nanocristal. A solubilidade de saturação dos nanocristais aumentou aproximadamente três vezes; como consequência, houve aumento na VDI em 2,2 vezes, 1,8 vezes e 3,8 vezes, quando comparado à VDI da furosemida micronizada em meio SGF, tampão 4,5 e SIF, respectivamente. Quanto às avaliações in silico dos nanocristais, sua absorção oral revelou moderada alteração no perfil farmacocinético. Quando foi utilizada a via de administração pulmonar, os nanocristais apresentaram maior desempenho quando comparada a via de administração oral; destacando-se o aumento na Fa% e na Cmáx e a acentuada diminuição no Tmáx. Em conclusão, a plataforma tecnológica obtida tem potencial aplicação no desenvolvimento de formas farmacêuticas inovadoras para administração pulmonar de furosemida. / According to the World Health Organization, hypertension is responsible for global public health crisis, being the cardiovascular diseases involved in approximately 17 million deaths a year, of these, 9.4 million occasioned by hypertension complications such as pulmonary edema. Regarding therapeutic arsenal available, Furosemide is a potent loop diuretic widely used in control and emergency situations related to hypertension and cardiogenic pulmonary edema. Despite the high level of prescribing, this drug belongs a class IV drug, according to Biopharmaceutics Classification System (BCS), exposing erratic and variable intestinal absorption. These characteristics represent a challenge for the development of oral dosage forms. Thus, adoption of innovative technologies associated with pulmonary route of administration may allow an alternative therapeutic approach, with high potential for application. Among the new technologies, those for obtaining nanocrystals of classes II and IV drugs have been a promising approach. Nanocrystals can exhibit in vivo higher performance when compared to their counterparts in micronized form. Therefore, strategies to develop medicines containing Furosemide, with greater efficacy and safety, are of critical importance. In this sense, the application of technology in silico, with predictive property, contributes to the rationalization of testing in research and development of new dosage forms. The objectives, as a result, were the preparation and the physicochemical characterization of Furosemide nanocrystals, and it\'s in silico evaluation on oral and pulmonary absorption using a computational tool. The nanocrystals were obtained using a high-energy milling technology under simultaneous revolution/rotation motion. The determination of the size distribution and morphology was performed using laser diffraction and scanning electron microscopy, respectively. Furthermore, differential scanning calorimetry, differential thermogravimetry, X-ray diffraction and Low Shift Raman spectroscopy were performed to investigate possible interactions and changes in the crystalline state of the nanocrystals. To measure the increase in the equilibrium solubility and dissolution rate, the shake flask and intrinsic dissolution rate (IDR) methods were used respectively. The nanocrystals size appeared thirty times lower (231 nm) compared to the initial size (7,1 &#181;m). The nanocrystals were stable with concern to its thermal characteristic not showing interactions between the excipients and the nanocrystals; however, they exhibited less defined crystal structure, indicating partial amorphization. The nanocrystals saturation solubility increased approximately three times. Consequently, 2.2, 1.8 and 3.8 folds increase were observed in IDR when compared to the Furosemide raw material in SGF, buffer 4.5 and SIF, respectively. The in silico nanocrystal studies revealed moderate changes in its oral absorption and pharmacokinetic profile. When the pulmonary route of administration was used, the nanocrystals showed higher performance compared to oral route administration; highlighting the increase in Fa % and Cmax and a significant decrease in Tmax. In conclusion, the technology platform obtained has potential application in the development of innovative dosage forms for Furosemide pulmonary delivery.

Durant ce travail, la synthèse de nanoparticules hybrides composées d'un coeur organique cristallin fluorescent enrobé d'une coquille silicatée a été optimisée dans l'optique du développement d'un nouveau type de traceurs très brillants pour l'imagerie médicale (microscopie de fluorescence excitée à deux photons). La préparation des nanoparticules a pu être adaptée à différents types de fluorophores organiques. La composition de la coquille organosilicatée peut elle aussi être modulée afin de modifier les propriétés de dispersion en solution aqueuse, la charge de surface des particules ou les fonctions chimiques de surface. Le coeur organique de ces particules se dissolvant dans les solvants organiques, différentes stratégies de fonctionnalisation en milieu aqueux ont été réalisées afin d'augmenter la furtivité de ces objets in vivo. Ces différentes méthodes ont permis de faire circuler les nanoparticules dans le flux sanguins de souris. La durée de vie de circulation de ces particules restant cependant courte, de nouvelles stratégies de fonctionnalisation (chimie click) devraient permettre à l'avenir d'allonger ce temps de circulation. / This work has allowed the synthesis of hybrid nanoparticles composed by organic crystal cores embedded in organosilicate shells for the development of in vivo imaging applications(two-photon fluorescence microscopy). The synthesis of these nanoparticles has been adapted with different types of organic dyes. The composition of the silicate shell can also be modulated in order to modify the properties of dispersion in aqueous solution, the surface charge of particles or chemical functions present at the surface. Due to the dissolution of organic cores in organic solvents, different strategies of functionalization were developed in aqueous media to enhance the furtivity of these nanoparticles in vivo. These methods have led to the circulation of the nanoparticles into the bloodstream of mice. However, the circulation lifetime of these nanoparticles is short. New strategies of functionalization (click chemistry) should help in the future to extend this circulation time for the possible development of these new fluorescent tracers.