Macromolecular complexes of anionic-nonionic block copolymers and cationic antibiotic aminoglycosides have been formed by electrostatic condensation. Amphiphilicity of the complexes was introduced into the shells by incorporating a hydrophobic poly(propylene oxide) segment into the block copolymer. The resulting particles have an average hydrodynamic diameter of ~ 200 nm and contain up to 30-40 % of the drug payload. In vitro efficacies of such nanostructures in reduction of intracellular pathogens like Salmonella, Listeria, and Brucella were demonstrated. Current effort focuses on translation of this nano-drug delivery concept to in vivo model of intracellular infectious diseases. Atom transfer radical polymerization (ATRP) was utilized to prepare well-defined polymeric dispersion stabilizers that readily adsorb onto metal oxide surfaces. Two unimolecular bis(phosphonate) ATRP initiators were designed and prepared in good yield. These special initiators were successfully used to initiate polymerization of poly(N-isopropylacrylamide) (PNIPAM) in a controlled manner yielding PNIPAM with a bis(phosphonate) moiety at one terminus. The polymers readily adsorbed onto magnetite nanoparticle surfaces, thus creating thermosensitive magnetic nanostructures that form nanosized clusters upon heating above the lower critical solution temperature of PNIPAM. It is envisioned that modularity of this approach, relying on the applicability of ATRP to polymerize a vast array of monomers, could be used to prepare a library of polymeric shells for magnetic iron oxide nanoparticles. Medical intervention in drug delivery that includes detectability of drug carriers is greatly desirable. A real-time assessment of disease prognosis could be highly beneficial for developing personalized treatment strategies. As an example of this conceptual innovation, block ionomer functionalized magnetite complexes were synthesized and investigated as carriers for delivery of aminoglycosides into phagocytic cells for treatment of intracellular bacterial infections. The ionic block of copolymer contains multiple carboxylates for binding onto the iron oxide surface. The remaining unbound carboxylate anions were used to complex with cationic gentamicin in nanoshells of these complexes. The iron oxide particle core provides an imaging modality and serves as a pseudo-crosslinking site to enhance stabilities of the polyelectrolyte complexes, thus preventing them from disintegrating in the physiological environment. Currently, these hybrid complexes are being investigated in possible pharmaceutical formulations to eradicate intracellular pathogens in animal models. / Ph. D.

Nucleic acid therapy holds real promise to offer less severe (lower side effects) as a treatment for life threatening and difficult to treat diseases such as cancer, heart disease or Alzheimer's disease. Theranostic nanomaterials that combine diagnostic imaging and therapeutic delivery, have potential to minimize the amount of time and dosage required for the treatment. This is achieved via delivery of nanoparticles that carry therapeutic payload as well as imaging agents; these agents need to circulate in the body longer due to its (larger) size and selectively accumulate in the tumor regions through the enhanced permeability and retention (EPR) effect. We have designed novel lanthanide (Gd, Tb or La) containing polymers with oligoethyleneamine and lanthanide chelating units to incorporate DNA binding and imaging agent functionality. Protonable amines along the polymer backbone electrostatically interact with DNA and compact it into a nanoparticle. These nanoparticles can be imaged both in vivo (Gd analogues, magnetic resonance imaging) and intracellularly (Tb chelation, fluorescence spectroscopy). Polymers were synthesized via step-growth polymerization to achieve a degree of polymerization of 18-24 for different analogues with varying amine number (three to six, N3-N6) along the backbone. Dynamic light scattering performed on the polyplexes (polymer-DNA complexes) indicate that they are in nanometer size range (50-80nm). All the polymers used to form polyplexes exhibited low toxicity to cultured human Glioblastoma cells (U-87) and showed variable transfection efficiency dependent on structure, comparable to G4 (sold as Glycofect"), a commercial transfection agent previously developed in our lab. This dissertation describes the first studies by the Reineke lab to monitor polyplex formation and destabilization using lanthanide resonance energy transfer (LRET). Polyplexes were formulated with Tb chelated N5 polymer and tetramethyl rhodamine (TMR) labeled pDNA, which are "LRET pairs". We observed decrease in luminescence intensity of Tb polymer (donor) in close proximity of TMR DNA (acceptor) in an intact polyplex at different N/P ratios. However, upon destabilization of polyplexes by addition of salt or heparin solution, the increase in distance between donor and acceptor resulted in increase in the luminescence intensity of Tb polymer. With the LRET technique, we are able to monitor formation and destabilization of polyplexes by monitoring change in luminescence of the donor chromophore (Tb). Polyplexes formulated with non-paramagnetic analogues (La chelated) of N4, polyethyleneimine (PEI) and G4 were studied using NMR to quantify free vs. bound polymer in a formulation. The amount of free polymer was measured by integrating the broad resonances from nanometer-sized particles (polyplexes) with narrow peaks from free polymer chains. This was supported by using an internal reference method to quantify free polymer amount from known internal reference concentration. We observed an increase in the amount of free polymer with N/P ratio for all three systems and both the methods showed comparable results. / Ph. D.

Yes / Glioblastoma (GBM) has a dismal prognosis. Evidence from preclinical tumor models and human trials indicates the role of GBM initiating cells (GIC) in GBM drug resistance. Here, we propose a new treatment option with tumor enzyme-activatable, combined therapeutic and diagnostic (theranostic) nanoparticles, which caused specific toxicity against GBM tumor cells and GICs. The theranostic cross-linked iron oxide nanoparticles (CLIO) were conjugated to a highly potent vascular disrupting agent (ICT) and secured with a matrix-metalloproteinase (MMP-14) cleavable peptide. Treatment with CLIO-ICT disrupted tumor vasculature of MMP-14 expressing GBM, induced GIC apoptosis and significantly impaired tumor growth. In addition, the iron core of CLIO-ICT enabled in vivo drug tracking with MR imaging. Treatment with CLIO-ICT plus temozolomide achieved tumor remission and significantly increased survival of human GBM bearing mice by more than 2 fold compared to treatment with temozolomide alone. Thus, we present a novel therapeutic strategy with significant impact on survival and great potential for clinical translation. / Heike E Daldrup-Link, NIH, R21CA176519 and R21CA190196; Sanjiv Sam Gambhir, NIH, 1U54CA199075; Jessica Klockow, NCI training grant, T32CA118681, Robert A. Falconer, University of Bradford, UoB-66031

Yes / Despite considerable progress with our understanding of glioblastoma multiforme (GBM) and the precise delivery of radiotherapy, the prognosis for GBM patients is still unfavorable with tumor recurrence due to radioresistance being a major concern. We recently developed a cross-linked iron oxide nanoparticle conjugated to azademethylcolchicine (CLIO-ICT) to target and eradicate a subpopulation of quiescent cells, glioblastoma initiating cells (GICs), which could be a reason for radioresistance and tumor relapse. The purpose of our study was to investigate if CLIO-ICT has an additive therapeutic effect to enhance the response of GBMs to ionizing radiation. Methods: NSG™ mice bearing human GBMs and C57BL/6J mice bearing murine GBMs received CLIO-ICT, radiation, or combination treatment. The mice underwent pre- and post-treatment magnetic resonance imaging (MRI) scans, bioluminescence imaging (BLI), and histological analysis. Tumor nanoparticle enhancement, tumor flux, microvessel density, GIC, and apoptosis markers were compared between different groups using a one-way ANOVA and two-tailed Mann-Whitney test. Additional NSG™ mice underwent survival analyses with Kaplan–Meier curves and a log rank (Mantel–Cox) test. Results: At 2 weeks post-treatment, BLI and MRI scans revealed significant reduction in tumor size for CLIO-ICT plus radiation treated tumors compared to monotherapy or vehicle-treated tumors. Combining CLIO-ICT with radiation therapy significantly decreased microvessel density, decreased GICs, increased caspase-3 expression, and prolonged the survival of GBM-bearing mice. CLIO-ICT delivery to GBM could be monitored with MRI. and was not significantly different before and after radiation. There was no significant caspase-3 expression in normal brain at therapeutic doses of CLIO-ICT administered. Conclusion: Our data shows additive anti-tumor effects of CLIO-ICT nanoparticles in combination with radiotherapy. The combination therapy proposed here could potentially be a clinically translatable strategy for treating GBMs.

Bien que de nombreux progrès aient été réalisés dans le traitement du cancer, de nouvelles approches sont nécessaires afin de minimiser les effets secondaires délétères et d’augmenter le taux de survie des patients. Aujourd’hui de nombreux espoirs reposent sur l’utilisation de nanoparticules (NPs) d’oxyde de fer fonctionnalisées permettant de combiner, en un seul nano-objet, le diagnostic (agent de contraste en IRM) et la thérapie par hyperthermie magnétique (i.e. « theranostic »). Dans ce contexte, la stratégie développée est la synthèse de NPs à propriétés magnétiques optimisées par le contrôle de leurs taille, forme et composition, leur biofonctionnalisation et la validation de leurs propriétés théranostiques. Une démarche d’ingénierie des NPs a été mise en place allant de la synthèse du précurseur de fer et de l’étude fine de sa décomposition en passant par l’étude in situ de la formation des NPs jusqu'à leur fonctionnalisation et la détermination de leurs propriétés theranostiques. / Despite numerous advances in cancer treatment, new approaches are necessary in order to minimize the deleterious side effects and to increase patient’s survivals rate. Nowadays, many hopes rely on functionalized iron oxide nanoparticles (NPs) that combine, in a single nano-objects, diagnosis (MRI contrast agent) and magnetic hyperthermia therapy (i.e. “theranostic”). In this context, the strategy is to develop the synthesis of optimized magnetic properties NPs through the control of their size, shape, composition, biofunctionalization and the validation of their theranostic properties. A process of NPs engineering has been developed starting at the iron precursor synthesis and the fine study of its decomposition passing through the in situ formation of the NPs to their functionalization and the determination of their theranostic properties.

L’objectif de ce travail a été la préparation de nanoparticules pour l’administration intratumorale. Ladouble functionalisation de ces nanoparticules est rapidement approuve comme extrement intéressant, car ellespeuvent être utilisé pour le diagnostic in vivo et la thérapie (théranostics). Pour réaliser ce type desnanoparticules, l’oxyde de fer a été choisi comme agent de contraste pour une utilisation en imagerie parrésonance magnétique (IRM) pour le diagnostic de cellules cancéreuse. Les nanoparticules d’oxyde de fer ont étépréparées dans des milieux aqueux et organique. La méthode d’émulsification multiple suivie de l’évaporationde solvant a été utilisée pour l’encapsulation concomitante d’un principe actif et des nanoparticules de l’oxydede fer. Tous les paramètres affectant la taille des nanoparticules pendant le procédé ont été étudiés en utilisantune molécule active hydrophile modèle (une dérivative de la Stilbene) et le protocole standard a ensuite étéévalué. Dans une seconde étape, les particules d’oxyde de fer ont été encapsulées par la même méthoded’émulsion évaporation et entièrement caractérisées en termes de morphologie, taille, magnétisation, etcomposition chimique. La visualisation in vitro des particules modèles a été réalisée par IRM et comparée a unproduit commercial à base de Gadolinium (Gd). D’autre part, la quantité nécessaire d’oxyde de fer permettantune bonne visualisation par IRM a été déterminée par une étude in vivo menée sur des souris. Enfin la doubleencapsulation d’oxyde de fer avec une molécule anticancéreuse a été effectuée par la méthode développée, laformulation obtenue a été entièrement caractérisée. / The objective of this work was the preparation of nanoparticles for intratumoral administration.Important characteristic was dual functionality of these nanoparticles that they can be used for diagnosis andtherapy so the resulting nanoparticles will serve as theranostic agents. For this purpose iron oxide was chosen asa contrast agent to be used in Magnetic resonance imaging (MRI) for diagnosis of cancerous cells. Iron oxidenanoparticles (IONPs) were prepared in aqueous and organic medium. A multiple emulsion evaporation methodwas designed for the encapsulation of active ingredient (hydrophilic drug i-e Stilbene) and the IONPs. All theparameters affecting the colloidal properties final hybrid particles were studied and characterization was done forfinal particles. Then prepared particles were evaluated for in vitro MRI and also compared with commerciallyavailable products such as gadolinium (Gd). At same time, the minimum detectable quantity of iron oxide in vivowas determined using a commercialized iron oxide emulsion on rat models. Finally an anticancer agent wasencapsulated with IONPs using same multiple emulsion method and characterization was done.

O câncer pode ser definido como um conjunto de mais de 100 doenças causadas pelo crescimento desordenado de células e está entre as cinco doenças que mais causam mortalidade no mundo. Por este motivo, pesquisas tem voltado sua atenção no desenvolvimento de novos fármacos e novos tratamentos que sejam mais eficazes e seletivos para o tratamento e diagnóstico dessas doenças. A terapia fotodinâmica (TFD) tem recebido merecido destaque, pois trata-se de uma terapia não invasiva e seletiva. Esta terapia consiste na ativação de um fotossensibilizador através da irradiação em determinado comprimento de onda da luz visível, que em presença de oxigênio molecular é capaz de produzir oxigênio singleto, desencadeando uma série de reações que culminam na produção de espécies reativas de oxigênio (ERO´s), citotóxicas às células. Portanto, a busca por fotossensibilizadores que sejam eficazes para o uso em TFD torna-se importante. As ftalocianinas são compostos que possuem características químicas que as fazem bons candidatos a fotossensibilizadores, pois possuem forte absorção no visível, são quimicamente estáveis e capazes de produzir oxigênio singleto. Combinar fotossensibilizadores com marcadores fluorescentes é uma estratégica interessante para expandir o uso da TFD, uma vez que desta maneira é possível aliar terapia com diagnóstico por imagem. Neste trabalho, propôs-se o estudo da transferência de energia que ocorre em um sistema combinando ftalocianinas de rutênio e nanopartículas fluorescentes, denominadas pontos quânticos (PQ´s). Foi avaliada também a potencialidade citotóxica de espécies que produzem oxigênio singleto (1O2) em terapia fotodinâmica de neoplasias. Paralelamente realizaram-se ainda os estudos fotoquímicos e fotofísicos, a fim de avaliar o sistema para aplicação em \"teranóstica\". Os resultados demonstraram que os complexos rutênio- ftalocianinas apresentaram características de um bom fotossensibilizador, uma vez que apresentaram citotoxicidade em células de linhagens tumorais após estímulo luminoso em baixas concentrações. Quanto à interação entre ftalocianinas e pontos quânticos, verificou-se que estas demonstraram serem bons supressores de fluorescência das nanopartículas, ocorrendo o mecanismo estático para esta supressão. / Cancer is one of the leading causes of death worldwide. Contemporary therapies do not bring the expected effectiveness and the treatment is often non-selective and its application is associated with several side effects, such as: the possibility of damage to genetic material or induction of secondary cancer process by radiotherapy; increasing resistance of tumor cells to chemotherapeutic agents, which translates into a high social and economic costs; significant reduction in the quality of life of patients underwent surgery and their long and expensive hospitalization. In contrast, antitumor photodynamic therapy (PDT) is a non-invasive method consisting of three components: a chemical compound called photosensitizer, light of a specific wavelength, and oxygen. This combination initiates a series of photochemical reactions leading to generation of reactive oxygen species and/or free radicals, which cause the death of cancer cells. Combining therapy and diagnostics has been the aim of many studies, improving the efficacy of the treatment. In this work, we propose the study of interaction between ruthenium phthalocyanines compounds and CdTe-MPA quantum dot, once in literature is described that quantum dots can transfer energy for phthalocyanines, increasing its citotoxycity. It was evaluated the cytotoxic effects of the species that produced singlet oxygen (1O2) and its effects with different axial ligand in the sctrucuture of ruthenium phthalocyanines complexes. It was performed also photophysics and photochemical studies to evaluate the system for theranotic purposes. The results showed that the ruthenium phthalocyanines are good photosensitizer candidates once it presented high cytotoxity effects against different cancer cells lines after irradiation, even in low concentrations. Regarding to the interaction between phthalocyanines and quantum dots, it was demonstrated that the complexes could quenched the nanoparticles fluorescence occurring the static quenching mechanism.

The persistence of high global mortality rates directly attributable to cardiovascular disease drives ongoing research into novel approaches for improved diagnosis and treatment of its primary underlying cause, atherosclerosis. Combined intravascular ultrasound and photoacoustic (IVUS/IVPA) imaging is one such modality, actively being developed as a tool for improved characterization of high-risk atherosclerotic plaques. The pathophysiology associated with progression and destabilization of atherosclerotic plaques leads to characteristic changes in arterial morphology and composition. IVUS/IVPA imaging seeks to expand upon the ability of clinically utilized intravascular ultrasound (IVUS) imaging to assess vessel anatomy by adding improved sensitivity to image the underlying cellular and molecular composition through intravascular photoacoustic (IVPA) imaging of either endogenous chromophores (e.g. lipid) or exogenously delivered contrast agents. This dissertation focuses on the expansion of IVUS/IVPA imaging using exogenous contrast agents to enable the detection and subsequent optically-triggered therapy of atherosclerotic plaques. The passive extravasation and aggregation of systemically injected plasmonic gold nanorods absorbing within the near infrared tissue optical window within plaques of atherosclerotic rabbit models is first demonstrated, along with the ability to localize the contrast agents using ex vivo IVUS/IVPA imaging. The motivation for nanoparticle labeling of atherosclerosis is then expanded from that of purely image contrast agents to vehicles for image-guided, dual-modality phototherapy. The integrated IVUS/IVPA imaging catheter is utilized for photothermal delivery with simultaneous IVPA temperature monitoring using the high optical absorption of gold nanorod contrast agents to enable localized heating. Subsequently, the potential role for IVUS/IVPA-guided phototherapy is further expanded through the characterization and in vitro assessment of novel multifunctional theranostic nanoparticles comprised of a gold nanorod core with a degradable, photosensitizer-doped silica shell. Together, the results presented within this dissertation provide a framework for ongoing research into the expansion of IVUS/IVPA imaging as a platform for complimentary diagnosis and local treatment of atherosclerotic plaques using multifunctional theranostic nanoparticle contrast agents. / text

L’objectif de cette thèse est de préparer et caractériser de nouveaux agents théranostiques potentiels à base de complexes de ruthénium portant des molécules biologiquement actives. Pour évaluer potentiel théranostique des nouveaux composés les propriétés de luminescence et la cytotoxicité ont été considérées. Quatre nouveaux ligands portant des substituants a activité biologique: 5-(4-4’-methyl-[2,2’-bipyridine]-4-ylbut-1-yn-1-yl)pyridine-2-carbaldehyde semicarbazone (L1), 3-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L2), 5,5-dimethyl-3-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L3) and [1-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)-2,5-dioxoimidazolidin-4-yl]urea (L4) ont été prepares, caractérisés et engagés dans la synthese des complexes de ruthénium correspondants. Six complexes ont été obtenus a partir du ligand L1 ([Ru(bpy)2(L1)]2+, [Ru(Mebpy)2(L1)]2+, [Ru(tBubpy)2(L1)]2+, [Ru(Phbpy)2(L1)]2+, [Ru(dip)2(L1)]2+, [Ru(SO3dip)2(L1)]2-) et trios a partir de L2, L3 and L4 ([Ru(bpy)2(L2)]2+, [Ru(bpy)2(L3)]2+, [Ru(bpy)2(L4)]2+) (bpy = 2,2’-bipyridine, Mebpy = 4,4’-dimethyl-2,2-bipyridine, tBubpy = 4,4’-tert-butyl-2,2’-bipyridine, Phbpy = 4,4’-diphenyl-2,2-bipyridine, dip = 4,7-diphenyl-1,10-phenantroline and SO3dip = 4,7-di-(4-sulfonatophenyl)-1,10-phenantroline). Les propriétés spectroscopiques et photophysiques des composés ont été étudiées. La présence des ligands L1-L4 conduit a une décroissance du rendement quantique et de la durée de vie de l’état excité en comparaison des complexes non substitués [Ru(bpy)3]2+. Des calculs DFT montrent que les ligands L1-L4 n’influencent pas la géométrie du complexe mais accroissent le niveau énergétique de la HOMO induisant des band gap HOMO-LUMO plus faibles. Les interactions entre les complexes et l’human serum albumin (HSA) ont été étudiées. Tous les complexes préparaés montrent une tres forte affinité pour HSA – La constante d’association 105 M-1s-1 témoigne de la formation d’adduits Ru-HSA stables. Il a aussi été démontré que les complexes de ruthénium se lient préférentiellement a la poche hydrophobe des protéine, située dans le site 1 de Sudlow dans le sous domaine II A. Des études préliminaires ont montré que les complexes de ruthénium préparés presentent une activité cytotoxique vis-à-vis de diverses lignées de cellules cancéreuses. Cette activité associée aux bonnes propriétés de luminescence (rendement quantique, durée de vie) fait des nouveaux complexes des candidats potentiels pour les applications théranostiques / The main goal of this thesis was synthesis and preliminary characterization of novel ruthenium(II) polypyridyl complexes bearing biologically active molecules as potential theranostic agents. Luminescence for the diagnostic applications, and cytotoxicity for the anticancer, therapeutic applications are considered as the theranostic properties. Four new ligands containing biologically active moieties - 5-(4-4’-methyl-[2,2’-bipyridine]-4-ylbut-1-yn-1-yl)pyridine-2-carbaldehyde semicarbazone (L1), 3-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L2), 5,5-dimethyl-3-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)imidazolidine-2,4-dione (L3) and [1-(5-4’-methyl-[2,2’-bipyridine]-4-ylpentyl)-2,5-dioxoimidazolidin-4-yl]urea (L4) were synthesized and characterized. The ligands were used to obtain nine novel ruthenium(II) polypyridyl complexes. Six complexes were synthesized with ligand L1 ([Ru(bpy)2(L1)]2+, [Ru(Mebpy)2(L1)]2+, [Ru(tBubpy)2(L1)]2+, [Ru(Phbpy)2(L1)]2+, [Ru(dip)2(L1)]2+, [Ru(SO3dip)2(L1)]2-) and three with ligands L2, L3 and L4 ([Ru(bpy)2(L2)]2+, [Ru(bpy)2(L3)]2+, [Ru(bpy)2(L4)]2+) (bpy = 2,2’-bipyridine, Mebpy = 4,4’-dimethyl-2,2-bipyridine, tBubpy = 4,4’-tert-butyl-2,2’-bipyridine, Phbpy = 4,4’-diphenyl-2,2-bipyridine, dip = 4,7-diphenyl-1,10-phenantroline and SO3dip = 4,7-di-(4-sulfonatophenyl)-1,10-phenantroline). The spectroscopic and photophysical properties of those complexes were determined. The presence of ligands L1-L4 in the structure of the complex decreased luminescence quantum yield and luminescence lifetime in comparison with unmodified [Ru(bpy)3]2+ complex. The theoretical calculations have shown that ligands L1-L4 do not have influence on ruthenium core geometry. However, they increased the energy of the HOMO that resulted in a shorter band gap. The simulated electronic absorption spectra were in a good agreement with the experimental data. The interactions between the studied ruthenium complexes and human serum albumin (HSA) were investigated. All studied Ru(II) complexes exhibited strong affinity to HSA with the association constant 105 M-1s-1, which suggests formation of Ru complex-HSA adducts. It was also determined that ruthenium complexes most likely bind to the hydrophobic pocket of protein, located in Sudlow’s site I in the subdomain II A. Preliminary cytotoxicity evaluation for the studied ruthenium complexes showed their cytotoxic activity towards cancer cell lines. Those results, together with good luminescence properties of the studied ruthenium complexes (luminescence lifetimes and luminescence quantum yield) make them interesting candidates for potential theranostic applications

Les systèmes théranostiques associant des propriétés thérapeutiques et des propriétés d'imagerie sont développés pour permettre le suivi de traitement in vivo. La stratégie que nous proposons dans cette thèse est de formuler des liposomes magnétiques thermosensibles chargés en principe actif pour traiter des tumeurs murines superficielles du côlon CT26. Ces nanovecteurs peuvent être accumulés dans les tumeurs par ciblage magnétique et le relargage du principe actif peut être déclenché par HIFU (Ultrasons Focalisés de Haute Intensité). Ces liposomes sont développés par co-encapsulation de nanoparticules de maghémite (?-Fe2O3) et de Combrétastatine A4 Phosphate (CA4P) dans des liposomes thermosensibles. La forte encapsulation des nanoparticules magnétiques dans les Liposomes Ultra-Magnétiques (LUM) permet à la fois le ciblage magnétique et leur suivi in vivo par IRM. Le chauffage par HIFU in vitro à la température de transition des membranes des LUM a permis une amélioration du relargage de la CA4P. La biodistribution des LUM in vivo a été évaluée par IRM dynamique de contraste de susceptibilité avec une résolution temporelle adaptée à la cinétique de capture des nanovecteurs, notamment par le foie. L'efficacité du ciblage magnétique a été démontrée grâce à une nouvelle méthode de traitement de l'histogramme des intensités IRM. Enfin, l'ajustement in vivo des séquences d'HIFU permet le relargage du principe actif. L'efficacité du traitement est ensuite suivie par IRM multiparamétrique anatomique, pondérée T2* de diffusion et de perfusion pour évaluer l'impact sur la fonctionnalité vasculaire et l'évolution tumorale, ainsi que par histologie. / Theranostic systems with imaging and therapeutic properties are developed to monitor treatments in vivo. The strategy we propose here is to design thermosensitive drug-loaded magnetic liposomes to treat superficial colon tumors CT26 on mice. These nanocarriers can be accumulated in the tumor by using a magnetic field gradient and the drug release can be triggered by a local heating induced by HIFU (High Intensity Focused Ultrasounds). They have been developed by co-encapsulation of magnetic nanoparticles and the antitumoral drug CA4P (Combretastatin A-4 Phosphate) in thermosensitive liposomes. The high loading of maghemite (γ-Fe2O3) magnetic nanoparticles enables both magnetic targeting and in vivo monitoring by MRI of this Ultra-Magnetic Liposomes (UML). In vitro HIFU heating at the UML membrane transition temperature improved the drug release. In vivo UML biodistribution was evaluated with dynamic susceptibility contrast imaging adjusted in time acquisition in MRI and the magnetic targeting efficiency was shown with a new MRI imaging processing. Adjustments of in vivo HIFU sequences to locally heat the tumor at the UML transition temperature allowed the triggering of drug release. Treatment efficiency was monitored by multiparametric diffusion, T2* weighted, anatomical and perfusion MRI and histology.