The studies presented here evaluate the biliary, parenchymal and vascular enhancement effects of two T1-shortening liver-specific contrast agents, Gd-BOPTA and Gd-EOB-DTPA, in Magnetic Resonance Imaging (MRI) of healthy subjects and of patients. Ten healthy volunteers were examined with both contrast agents in a 1.5 T MRI system using three-dimensional gradient echo sequences for dynamic imaging until five hours after injection. The enhancement of the common hepatic duct in contrast to the liver parenchyma was analyzed in the first study. This was followed by a study of the image contrasts of the hepatic artery, portal vein and middle hepatic vein versus the liver parenchyma. While Gd-EOB-DTPA gave an earlier and more prolonged enhancement and image contrast of the bile duct, Gd-BOPTA achieved higher maximal enhancement and higher image contrast for all vessels studied during the arterial and portal venous phases. There was no significant difference in the maximal enhancement obtained in the liver parenchyma. In a third study, another 10 healthy volunteers were examined with the same protocol in another 1.5 T MRI system. Using signal normalization and a more quantitative, pharmacokinetic analysis, the hepatocyte-specific uptake of Gd-EOB-DTPA and Gd-BOPTA was calculated. A significant between-subjects correlation of the uptake estimates was found and the ratio of these uptake rates was of the same magnitude as has been reported in pre-clinical studies. The procedure also enabled quantitative analysis of vascular enhancement properties of these agents. Gd-BOPTA was found to give higher vessel-to-liver contrast than Gd-EOB-DTPA when recommended doses were given. In the final study, retrospectively gathered datasets from patients with hepatobiliary disease were analyzed using the quantitative estimation of hepatic uptake of Gd-EOB-DTPA described in the third study. The uptake rate estimate provided significant predictive ability in separating normal from disturbed hepatobiliary function, which is promising for future evaluations of regional and global liver disease. In conclusion, the differing dynamic enhancement profiles of the liver-specific contrast agents presented here can be beneficial in one context and challenging in another. Diseases of the liver and biliary system may affect the vasculature, parenchyma or biliary excretion, or a combination of these. The clinical context in terms of the relative importance of vascular, hepatic parenchymal and biliary processes should therefore determine the contrast agent for each patient and examination. A quantitative approach to analysis of contrast-enhanced liver MRI examinations is feasible and may prove valuable for their interpretation.

L'IRM (Imagerie par Résonance Magnétique) est une technique de choix pour l'imagerie moléculaire, soit la visualisation d'événements biologiques à l'échelle moléculaire. En effet, elle est non invasive et possède une haute résolution. Cependant, elle manque de sensibilité. L'utilisation d'agents de contraste commerciaux, qui sont pour la plupart des chélates de Gd(III), peut pallier à ce problème lors d'examens cliniques mais ils ne sont pas assez efficaces en vue de l'imagerie moléculaire. Leur efficacité, définie par leur relaxivité, peut être améliorée en optimisant les paramètres qui la gouvernent, comme le nombre de molécules d'eau coordinées, la vitesse d'échange de l'eau ou la dynamique de rotation du complexe. Deux stratégies sont envisagées pour améliorer la sensibilité : la première est de rassembler un grand nombre de complexes de Gd(III) possédant une haute relaxivité dans une seule entité ; la seconde est la conception de sondes bimodales IRM/imagerie optique, permettant de tirer profit à la fois de la haute résolution de l'IRM et de la très bonne sensibilité de l'imagerie optique.Ce travail de thèse a consisté à incorporer des agents de contraste à base de Gd(III) possédant des propriétés de relaxivité améliorées dans des systèmes macromoléculaires ou des nanobjets. Pour cela, des complexes ayant des paramètres de relaxivité optimisés connus au laboratoire ont été fonctionnalisés pour être greffés sur des quantum dots, pour le caractère bimodal et sur des oligonucléotides afin de réaliser des sondes ADN. L'utilisation de billes de silice a permis d'incorporer des complexes de Gd(III) de manière non covalente et d'obtenir à la fois une relaxivité par Gd(III) et par particule très élevée. L'incorporation simultanée de complexes d'Yb(III) permet également d'obtenir une sonde bimodale avec une émission dans le proche infrarouge. Tous ces systèmes ouvrent la possibilité au développement de sondes IRM avec des propriétés optimisées, prometteuses pour l'imagerie moléculaire. / Magnetic Resonance Imaging (MRI) is a widely used diagnostic method in medicinal practice. It is the ideal technique for molecular imaging, which allows biological events to be observed at the molecular scale thanks to its high resolution. However it has a very low sensitivity. Commercial contrast agents can palliate this lack of sensitivity, but their efficiency, defined as relaxivity, is too low for molecular imaging. The relaxivity of Gd(III) chelates depends on parameters such as the hydration number, the exchange rate and the rotational dynamics of the complex, which can be optimized to improve the relaxivity. Two strategies can be considered to improve the sensitivity: the first one is to gather a high number of complexes demonstrating an optimized relaxivity on a nanoobject ; the second one is the design of a bimodal probe MRI/Optical imaging to combine the high resolution of MRI and the high sensitivity of optical imaging.In this work we present the incorporation of gadolinium chelates into macromolecular systems and two different types of nanoobjects. Gd(III) chelates with improved relaxometric properties have been functionalized and grafted onto quantum dots for the design of a bimodal probe and into oligonucleotides for the conception of a DNA probe. The non-covalent incorporation of Gd(III) in silica spheres allows both a high relaxivity per Gd(III) and per particle. The simultaneous incorporation of Yb(III) complexes emitting in the near infrared permits the design of a bimodal probe. All of these systems lead to the development of a new class of promising probes for molecular imaging.

Ce travail de thèse traite de l’élaboration de nanoparticules luminescentes à based’organolanthanides pour des applications d’imagerie biomédicale ou de marquage pour la lutte anticontrefaçon. Les organolanthanides ont été incorporés sans liaison covalente afin de préserver leursremarquables propriétés de luminescence et leur stabilité chimique. Deux types de nanoparticulesont été étudiés, des particules de latex et des billes de silice qui ont toutes les deux été synthétiséesen milieu hétérogène.La silice a été synthétisée par un procédé sol-gel en microémulsion inverse. Deux organolanthanidesluminescents initialement dissous dans les micelles inverses ont été piégés physiquement dans lasilice amorphe pendant sa formation. Une nouvelle méthode basée sur la quantification de l’activitéd’un isotope radioactif de l’Eu(III) a été développée pour étudier l’incorporation desorganolanthanides. Les propriétés physico-chimiques des organolanthanides influencent directementleur localisation au sein des particules et l’efficacité d’incorporation. L’étude approfondie de cesnanoparticules a permis de mettre en évidence une amélioration de la relaxivité d’un complexe deGd(III) quand il est confiné dans la silice.Les particules de latex ont été synthétisées par polymérisation radicalaire en miniémulsion directe.Différents organolanthanides de structures ionique ou non ionique ont été incorporés efficacementpar simple dissolution dans le monomère. L’incorporation du complexe de structure ionique anécessité l’utilisation d’un tensioactif cationique afin de le maintenir à l’intérieur des gouttelettes etgarantir son incorporation dans les particules de latex. Ce système permet d’incorporer un grandnombre de complexes et aucun relargage n’est observé après plusieurs mois. Le ligand utilisé permeten plus d’exciter jusqu’à dix terre rares simultanément. En faisant varier la nature et la quantité desorganolanthanides incorporés, il est ainsi possible de générer des codes optiques complexes sousune excitation unique. / This work deals with the elaboration of luminescent nanoparticles based on organolanthanides forbioimaging and optical coding. The organolanthanides were embedded without covalent linking inorder to preserve their remarkable luminescent properties and chemical stability. Two differenttypes of nanoparticles have been studied: polymer latexes and silica particles that were bothsynthesized in dispersed media.The silica nanoparticles were synthesized by a reverse microemulsion-mediated sol-gel process. Twoluminescent lanthanide chelates originally dissolved into water droplets were physically trapped intothe amorphous silica during its formation. A novel method based on a radioactive Eu(III) probe hasbeen developed to study the incorporation process. The physicochemical properties of the differentchelates had a strong influence on their localization within the particles and on the measuredincorporation efficiencies. This study finally allowed us to investigate the effect of Gd(III) complexesconfinement into silica nanoparticles.Luminescent polymer latexes based on organolanthanides have been synthesized by miniemulsionpolymerization. Several organolanthanides exhibiting a ionic structure or a non-ionic structure havebeen efficiently embedded into latex particles by simple dissolution in the corresponding monomers.For the ionic lanthanide chelate, a cationic surfactant was used to maintain the organolanthanidecomplex inside the droplets and guaranty and efficient incorporation. The resulting polymericluminescent nanoparticles showed excellent stability over leakage and a high loading capacity. Thisparticular ligand is able to efficiently sensitize over ten luminescent lanthanides, emitting in thevisible, the NIR or both regions. This allowed us to generate a large variety of color codes based onluminescence by tuning the emission signal using several lanthanide ions.

NMR is gaining increasing interest in civil engineering for applications regarding microstructure characterization as e.g., to determine pore sizes or to monitor moisture transport in porous materials. This study reveals the capability of NMR as a tool for pore size characterization. Therefore, we measured floor screed and synthetic materials at partial and full saturation. For most examined materials, the pore size distribution was successfully determined using either a reference or a calibration method. Since diffusion effects were observed for some samples in single-sided NMR measurements, further tests employing an NMR core analyzer were carried out in a homogeneous magnetic field. The finally obtained surface relaxivity of floor screed (50 μm/s) resulted to be much higher than suggested by literature.

This thesis discusses Nuclear Magnetic Resonance (NMR) techniques for formation evaluation in well log analysis for the oil/gas industry. We present the standard ingredients for NMR data processing and interpretation, and develop a methodology that extends the determination of surface relaxivity from the laboratory to the well site. The methodology consists of a processing algorithm for diffusion editing data, which enables surface relaxivity determination for conditions close to those found in well logging (regarding data availability and noise levels). At moderate noise levels, lower relaxivity values (below 10μm/s) can be determined solely from NMR diffusion data, while higher values (∼30μm/s) can be separated from intermediate ones. Application for actual logging data still requires some noise reduction techniques such as stationary measurements downhole or data stacking among different depths. However, it provides a way of converting T2 distributions into actual pore size distributions even for downhole acquisitions, before the samples get to the laboratory for routine analysis. Besides the logging analysis, we also developed a theoretical approximation to the diffusion equation with partial absorptive contour conditions, by calculating appropriate transition rates between cells in an arbitrary grid, allowing a simple methodology for obtaining the NMR data based on pore imaging. Calculated rates can in principle be used for modeling/understanding different diffusion phenomena, such as exchange between pores or relaxation sites. / Neste trabalho são discutidas técnicas de Ressonância Magnética Nuclear (RMN) aplicadas à avaliação de formações por meio da perfilagem de poços pela indústria de óleo e gás. São apresentados os conceitos básicos para processamento e interpretação dos dados de RMN, e desenvolvida uma metodologia para determinação da relaxatividade superficial em poço. O método consiste em um algoritmo de processamento de dados de diffusion editing, que permite a obtenção da relaxatividade superficial em condições próximas as encontradas na perfilagem de poços de petróleo (em relação à disponibilidade de dados e nível de ruído). Para níveis moderados de ruído, as relaxatividades mais baixas (menores que 10μm/s) podem ser determinadas através das medidas de difusão por RMN, enquanto valores mais altos (∼30μm/s) podem ser separados dos intermediários. Aplicações em dados de perfilagem ainda requerem técnicas de redução de ruído como aquisições estacionárias em poço ou empilhamento de dados ao longo de um intervalo de profundidades. Entretanto, o método possibilita uma forma de converter as distribuições de T2 em distribuições de tamanhos de poros ainda em poço, antes que as amostras sejam enviadas para o laboratório em análises de rotina. Além da perfilagem, foi desenvolvido também uma aproximação para a equação de difusão com condições de contorno absortivas, através de equações de taxas. A forma das taxas de transição permite o desenvolvimento de metodologias simples para obtenção dos dados de RMN através de imagens dos poros das rochas. As taxas de transição podem ser utilizadas também para a modelagem de outros fenômenos que envolvam difusão, como fenômenos de troca entre poros ou entre sítios com diferentes valores de relaxação.

L'état d'art concernant l'élaboration des matériaux inorganiques multifonctionnels, à l'échelle nanométrique, a fait l'objet de nombreuses recherches depuis vingt ans. Les réseaux de coordination tridimensionnels d'analogues de bleu de Prusse présentent des propriétés magnétiques modulables par l'application d'un stimulus extérieur (champ magnétique, irradiation lumineuse, pression ou variation de température etc...) qui mènent à une variété d'applications notamment pour le stockage de l'information et pour l'imagerie médicale. C'est dans ce cadre que s'inscrit ce travail de thèse.L'objectif principal porte sur la synthèse, la caractérisation chimique et structurale et l'étude des propriétés magnétiques, photomagnétiques et de relaxivité de nano-objets multicouches de ces réseaux. Dans une première partie, nous avons cherché à élaborer des nanoparticules de l'analogue CsCoFe(CN)6 du bleu de Prusse photomagnétique de tailles bien contrôlées. La synthèse met en jeu plusieurs facteurs qui influent la taille et l’homogénéité des particules. Ainsi une croissance contrôlée de la taille a été obtenue permettant de sonder l’effet de la taille sur la réponse photomagnétique. L’assemblage de ces particules sur un substrat de graphite orienté HOPG a permet d’obtenir une monocouche compacte sur plusieurs microns qui conduit à une croissance de films d’épaisseurs contrôlées. Le comportement photomagnétique a été étudié sur ces films. Dans la deuxième partie, nous nous sommes également intéressés à combiner, toujours à l’échelle nanométrique, cet analogue photomagnétique à un autre réseau ferromagnétique CsNiCr(CN)6 dans le but de créer une réponse exaltée sous lumière à plus haute température. Un comportement synergique est observé dans de telles hétérostructures et se manifeste par (i) une aimantation présentant un renversement uniforme des deux composantes et (ii) une augmentation photo-induite de l'aimantation qui persiste jusqu’à la température d’ordre du ferromagnétique.La dernière partie est consacrée à la synthèse d’agents de contraste nanométriques de réseaux de coordination. D'une part, des nanoparticules de bleu de Prusse KFeFe(CN)6 de tailles différentes ont été synthétisées avec un excellent contrôle de la taille. Les valeurs de relaxivité de la composante longitudinale T1 du temps de relaxation montrent une dépendence de la taille et du taux d’atomes paramagnétiques en surface. D'autre part, nous avons élaboré un alliage MnxIn1-xFe(CN)6 avec différentes proportions en manganèse, différentes tailles ont été obtenues en fonction du taux de manganèse inséré. Nous avons démontré que les ions MnII sont localisés en surface dans une structure proche de la structure cœur-coquille qui explique les valeurs élevées observées. Les valeurs élevées de la relaxivité de ces particules en font d’excellents candidats en tant qu’agents de contraste pour l‘imagerie à résonance magnétique (IRM). Afin d’explorer leurs potentialités, les particules de KFeFe(CN)6 de 6 nm et de Mn0.3In0.7Fe(CN)6, présentant la plus grande valeur de relaxivité, ont été enrobées par un polymère fluorescent biocompatible et internalisées au sein des cellules vivantes. Des tests de toxicité ont été aussi effectués. / Designing new objects in the perspective of creating useful functionalities at the nanoscale has been the subject of intense research efforts during the last 20 years. In the field of molecular magnetism, coordination nanoparticles (CNP) are among the most fascinating materials in the field of molecular magnetism because they may show bistability at room temperature under the effect of different external stimuli such as light, temperature, pressure, electrical field, etc…. The new and elegant route to stabilize negatively charged surfactant-free nanoparticles in water permitting an epitaxial growth of successive the layers of the same or of different Prussian Blue Analogues described by some of us was used in this work to design core-multi-shell nanocrystals with a fine tuning of their thickness. These network structures may be useful for several applications such as data storage and medical imaging.In the first part, we describe the synthesis of well controlled photomagnetic CsCoFe(CN)6 nanoparticles. The synthesis involves several factors that influence the size and homogeneity of the particles. The controlled growth of the size objects was also performed to investigate the effect of the size on the photomagnetic response. The assembly of these particles on oriented graphite (HOPG) substrates leads to a compact monolayer of several microns. The compact monolayers were used as template for the controlled growth of photomagnetic films. In the second part, we report the synthesis of sub-50 nm heterostructured nano-objects in which a ferromagnetic network of CsNiCr(CN)6 is combined to a photo magnetic CsCoFe(CN)6 layer in order to achieve synergy between the two components. The synergistic behavior is observed in such heterostructures and manifested by (i) a uniform reversal of the magnetization and (ii) a persistent increase of the photo-induced magnetization up to the “ordering” temperature (60 K) of the ferromagnetic component.The last part is devoted to the synthesis of nanosized coordination networks contrast agents. First, Prussian blue nanoparticles KFeFe(CN)6 with different sizes were prepared with excellent size control. Relaxivity values of the longitudinal component T1 of the relaxation time were found to depend on the size and the rate of the paramagnetic atoms present on the surface. On the other hand, we describe the synthesis of MnxIn1-xFe(CN)6 nanoparticles with different proportions of Mn. Different sizes were obtained, which depend on the rate of inserted Mn ions. We have demonstrated that the MnII ions are located on the surface in a sub-core-shell structure, which explains the high relaxivity values. The high relaxivity values of these particles show that they are excellent candidates as contrast agents for magnetic resonance imaging (MRI).

This thesis discusses Nuclear Magnetic Resonance (NMR) techniques for formation evaluation in well log analysis for the oil/gas industry. We present the standard ingredients for NMR data processing and interpretation, and develop a methodology that extends the determination of surface relaxivity from the laboratory to the well site. The methodology consists of a processing algorithm for diffusion editing data, which enables surface relaxivity determination for conditions close to those found in well logging (regarding data availability and noise levels). At moderate noise levels, lower relaxivity values (below 10μm/s) can be determined solely from NMR diffusion data, while higher values (∼30μm/s) can be separated from intermediate ones. Application for actual logging data still requires some noise reduction techniques such as stationary measurements downhole or data stacking among different depths. However, it provides a way of converting T2 distributions into actual pore size distributions even for downhole acquisitions, before the samples get to the laboratory for routine analysis. Besides the logging analysis, we also developed a theoretical approximation to the diffusion equation with partial absorptive contour conditions, by calculating appropriate transition rates between cells in an arbitrary grid, allowing a simple methodology for obtaining the NMR data based on pore imaging. Calculated rates can in principle be used for modeling/understanding different diffusion phenomena, such as exchange between pores or relaxation sites. / Neste trabalho são discutidas técnicas de Ressonância Magnética Nuclear (RMN) aplicadas à avaliação de formações por meio da perfilagem de poços pela indústria de óleo e gás. São apresentados os conceitos básicos para processamento e interpretação dos dados de RMN, e desenvolvida uma metodologia para determinação da relaxatividade superficial em poço. O método consiste em um algoritmo de processamento de dados de diffusion editing, que permite a obtenção da relaxatividade superficial em condições próximas as encontradas na perfilagem de poços de petróleo (em relação à disponibilidade de dados e nível de ruído). Para níveis moderados de ruído, as relaxatividades mais baixas (menores que 10μm/s) podem ser determinadas através das medidas de difusão por RMN, enquanto valores mais altos (∼30μm/s) podem ser separados dos intermediários. Aplicações em dados de perfilagem ainda requerem técnicas de redução de ruído como aquisições estacionárias em poço ou empilhamento de dados ao longo de um intervalo de profundidades. Entretanto, o método possibilita uma forma de converter as distribuições de T2 em distribuições de tamanhos de poros ainda em poço, antes que as amostras sejam enviadas para o laboratório em análises de rotina. Além da perfilagem, foi desenvolvido também uma aproximação para a equação de difusão com condições de contorno absortivas, através de equações de taxas. A forma das taxas de transição permite o desenvolvimento de metodologias simples para obtenção dos dados de RMN através de imagens dos poros das rochas. As taxas de transição podem ser utilizadas também para a modelagem de outros fenômenos que envolvam difusão, como fenômenos de troca entre poros ou entre sítios com diferentes valores de relaxação.

L’imagerie par résonnance magnétique trouve depuis ces dernières années des applications notables dans le domaine de l’imagerie moléculaire, qui représente un atout considérable pour l’investigation et la compréhension des processus biologiques. Des agents de contraste dits « intelligents » et spécifiques du processus physiologique que l’on souhaite détecter (pH, température, concentration en ion métallique, métabolite, etc.) sont alors développés. Cette thèse se concentre sur le développement et l’étude de nouveaux agents de contraste conçus pour la détection spécifique de l’activité enzymatique. Ces agents consistent en un complexe de lanthanide paramagnétique de type LnDO3A couplés par le biais d’un espaceur (auto-immolable par exemple) au substrat spécifique de l’enzyme ciblée. Après coupure du substrat par l’enzyme, la structure chimique de l’agent de contraste est modifiée entrainant des variations significatives de la relaxivité et des propriétés paraCEST des complexes. La caractérisation physico-chimique de certains complexes de Ln³⁺ et de Mn²⁺ a été réalisée. Les complexes de Gd³⁺ étudiés ont eu des réponses enzymatiques T1 prometteuses et les complexes de Ln³⁺ paramagnétiques étudiés (autres que Gd³⁺) ont montré une possible détection paraCEST de l’activité enzymatique. Les paramètres influençant l’effet CEST (structure moléculaire du complexe, choix du lanthanide, etc.) ont également été mis en évidence. Cependant la coupure enzymatique de certains composés reste encore à améliorer. / Over the past years, Magnetic Resonance Imaging has found significant applications in the field of molecular imaging, which is a considerable asset for investigating and understanding biological processes. Towards this objective, smart or responsive contrast agents (CA) which are specific of the physiological phenomenon that we aim to visualize (pH, temperature, metal ion concentration, metabolites, etc.) have been widely explored. This thesis focuses on the synthesis and the investigation of novel CAs designed for specific detection of enzyme activities. These CAs consist of a DO3A-type lanthanide chelate coupled via a spacer (e.g. a self-immolative linker) to an enzyme-specific substrate. After cleavage of the substrate by the enzyme, the CA’s chemical structure is modified leading to significant variations in the relaxivity or the paraCEST properties of the complexes. In this context, the physical chemical characterization of several Ln³⁺ and Mn²⁺ complexes has been achieved. Some Gd³⁺ complexes showed promising T1 responses while other paramagnetic Ln³⁺ complexes (Ln³⁺ = other than Gd³⁺) exhibited interesting paraCEST properties for enzymatic detection. The parameters affecting CEST properties (e.g. molecular structure of the complex, choice of lanthanide, etc.) have also been widely investigated. Nevertheless, the enzymatic cleavage of some compounds still need to be improved.

Le travail présenté dans ce mémoire de thèse avait pour but de synthétiser de nouveaux composés pour des applications en imagerie médicale. La première partie porte sur la synthèse de ligands hétéroleptiques pour la chélation de deux métaux différents en vue d’une utilisation dans deux types d’imagerie. Pour cela, nous avons d’abord synthétisé des porphyrines. Ces molécules sont connues pour la chélation de nombreux métaux de transition et notamment le cuivre, dont l’isotope cuivre-64 est un radioémetteur β+ utilisable en Tomographie par Émission de Positron (TEP). Ces porphyrines ont été couplées à un dérivé du DOTA, molécule connue pour son application, après métallation avec du gadolinium, en Imagerie par Résonance Magnétique (IRM). Ces composés possèdent des valeurs de relaxivité encourageantes pour une application en IRM. Enfin, des biomolécules ont été modifiées afin de vectoriser nos composés. La seconde partie porte sur la synthèse de composés pour l’imagerie médicale par optique non-linéaire. Nous avons dans un premier temps synthétisé des porphyrines amphiphiles et zwiterrioniques pour la Génération de Second Harmonique (GSH). Leur efficacité a été mesurée et celle-ci est suffisante pour pouvoir envisager l’obtention d’images. Dans un second temps, nous avons travaillé sur la synthèse d’un composé pour une application en imagerie biphotonique et en IRM. Pour cela, nous avons relié un dérivé du DOTA avec un fluorophore de type DPP. Le composé final a été métallé avec du gadolinium et sa relaxivité est supérieure à celle du DOTA(Gd). / The goal of my PhD studies was to synthesize new compounds for possible medical imaging applications. The first part of my thesis focused on the synthesis of heteroleptic ligands to achieve the chelation of two different metals aimed at addressing two types of medical imaging. We first synthesized porphyrins, which are well-known for the chelation of numerous transition metals. We focused on copper, whose copper-64 isotope is a β+ emitter usable in Positron Emission Tomography (PET). These porphyrins have been coupled with a DOTA derivative. This molecule, metallated with gadolinium, is well-known in Magnetic Resonance Imaging (MRI). Our compounds display encouraging relaxivities for MRI applications. At last, these molecular probes have been conjugated to a few biomolecules in order to vectorize our compounds. The second part of this work is related to the synthesis of fluorophores for nonlinear optical imaging. We first synthesized amphiphilic zwitterionic porphyrins for Second Harmonic Generation (SHG). The efficiency of these compounds has been measured and was satisying enough to consider the possibility to perform imaging studies. We also worked on the synthesis of compounds for Two Photon Emission Fluorescence (TPEF) imaging and MRI. We have linked a DOTA derivative with a diketopyrrolopyrrole (DPP). This conjugate has been metallated with gadolinium and its relaxivity has been measured. Interestingly, this value is superior to that of DOTA(Gd).

The controllable design of magnetic nanocarriers is essential for advanced in vivo applications such as magnetic resonance image-guided therapeutic delivery and alternating magnetic field-induced remote release of drugs. This work describes the fabrication of polymer-stabilized nanoparticles encapsulating imaging and therapeutic agents and delineates relationships among materials parameters and response. The effect of aggregation of magnetic iron oxide nanoparticles in aqueous suspension was characterized using a well-defined core-corona complex comprised of a superparamagnetic magnetite nanoparticle stabilized by terminally-anchored poly(N-isopropylacrylamide) (PNIPAM) corona. The modified Vagberg density distribution model was employed to verify that the complexes were individually dispersed prior to aggregation and was found to accurately predict the intensity-weighted hydrodynamic diameter in water. Aggregation of the complexes was systematically induced by heating the suspension above the lower critical solution temperature (LCST) of the polymer, and substantial increase in the NMR transverse relaxation rates was noted. Controlled clusters of primary iron oxide nanoparticles stabilized by the biodegradable block copolymer, poly(ethylene oxide-b-D,L-lactide) were fabricated by a scalable, rapid precipitation technique using a multi-inlet vortex mixer. Quantitative control over iron oxide loading, up to 40 wt%, was achieved. Correlations between particle parameters and transverse relaxivities were studied within the framework of the analytical models of transverse relaxivity. The experimental relaxivities typically agreed to within 15% with the values predicted using the analytical models and cluster size distributions derived from cryo-transmission electron microscopy. Hydrophilic-core particles assembled using the poly(ethylene oxide-b-acrylate) copolymer and at similar primary nanoparticle sizes and loadings had considerably higher transverse (r2) and longitudinal (r1) relaxivities, with r2s approaching the theoretical limit for ~ 8 nm magnetite. Block copolymer nanoparticles comprised of poly(D,L-lactide) and poly(butylene oxide) cores were utilized to encapsulate the poorly water-soluble antiretroviral drug, ritonavir, at therapeutically-useful loadings. Controlled size distributions were achieved by incorporation of homopolymer additives, poly(L-lactide) or poly(butylene oxide) during the nanoparticle preparation process. Nanoparticles either co-encapsulating a highly hydrophobic polyester poly(oxy-2,2,4,4-tetramethyl-1,3-cyclobutanediyloxy-1,4-cyclohexanedicarbonyl) within the core or possessing crosslinkable groups around the core were also successfully fabricated for potential sustained release of ritonavir from block copolymer carriers. / Ph. D.