Dissertations / Theses on the topic 'Nano contrast agents'

La micro-tomodensitométrie à rayons X (dite micro-CT, CT = Computed Tomography), est une technique d’imagerie de haute résolution qui consiste d’une part à mesurer l’absorption des rayons X par les tissus, et d’autre part de reconstruire les images et les structures anatomiques en 3 dimensions par traitement informatique. L’agent de contraste est une substance capable d’améliorer la visibilité des structures d’un organe ou d’un liquide organique in vivo. Ce travail de thèse a eu pour objectif le développement d’agents de contraste iodés sous formes de nano-émulsions pour des applications précliniques en imagerie biomédicale. Nous nous sommes proposés d’étudier d’une part des nano-émulsions iodées afin d’avoir une longue rémanence vasculaire in vivo, une meilleure biocompatibilité et d’autre part de mettre au point une synthèse et une formulation plus simples que celles des agents de contraste nanoparticulaires commercialisés. Trois différentes huiles iodées ont été synthétisées et utilisées comme partie contrastante dans les nano-émulsions. Enfin, les nano-émulsions de l’α-tocophérol iodé nous ont permis d’atteindre l’objectif de cette thèse. Ces nano-émulsions iodées ont montré une très bonne biocompatibilité et combinent à la fois les propriétés d’un agent de contraste à longue rémanence vasculaire et un agent de contraste spécifique du foie<br>The X-ray microtomography (called mico-CT, CT = Computed Tomography) is a high-resolution X-ray tomography, uses X-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model. The contrast agent is a substance used to enhance the contrast of structures or fluids within the body in medical imaging. The purposes of the thesis were the development of iodine-containing nano-emulsion based contrast for preclinical applications in biomedical imaging. We proposed to study blood pool contrast agents based on iodine-containing nano-emulsions and to develop simpler procedure for the preparation of these iodine-containing nano-emulsions. Three different iodinated oils were synthesized and used as the contrasting part in the nano-emulsions. Finally, nano-emulsions of iodinated α-tocopherol have been enabled us to achieve the purpose of the thesis. These iodinated nano-emulsions demonstrated very good biocompatibility and showed prolonged and significant contrast enhancement in both bloodstream and liver tissues

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2015.<br>Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-05-20T16:15:58Z No. of bitstreams: 1 2015_JulioCesarEloiBitencourt.pdf: 1806458 bytes, checksum: 0a8d7f915ee4b218ac6e545c68b94610 (MD5)<br>Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-05-20T16:54:47Z (GMT) No. of bitstreams: 1 2015_JulioCesarEloiBitencourt.pdf: 1806458 bytes, checksum: 0a8d7f915ee4b218ac6e545c68b94610 (MD5)<br>Made available in DSpace on 2016-05-20T16:54:47Z (GMT). No. of bitstreams: 1 2015_JulioCesarEloiBitencourt.pdf: 1806458 bytes, checksum: 0a8d7f915ee4b218ac6e545c68b94610 (MD5)<br>Os agentes de contraste iodados atuais causam diversos efeitos adversos e não proporcionam imageamento por período maior que trinta minutos surgindo a necessidade pela busca por agentes de contraste que diminuam os efeitos adversos e propiciem um imageamento de longo prazo. Nesse sentido o desenvolvimento de um agente de contraste iodado nanoestruturado torna-se promissor uma vez que sua estrutura nano traz por si a diminuição dos efeitos adversos e esta permite controlar o tempo que o agente de contraste permanecerá no organismo fornecendo assim um imageamento mais prolongado. O presente estudo desenvolveu uma nova formulação nanoestruturada contendo agentes de contraste iodados para a utilização em raio-x utilizando duas vias de síntese, uma com carreadores nanoestruturado lipídicos, o que posteriormente demonstrou ser inviável, e a utilização das Bases de Schiff, que demonstrou ser promissora. Os carreadores nanoestruturados lipídicos demonstraram a impossibilidade de ligação covalente do iodo ao ácido graxo, fazendo com que o iodo se deslocasse facilmente para o meio, o que é inviável para um agente de contraste. As Bases de Schiff formadas se ligaram covalentemente ao iodo fazendo com que este não fosse para o meio fornecendo a formação de um agente de contraste seguro. Antes da iodação as base de Schiff foram acopladas a moléculas de ácido graxo de sete carbonos para conferir hidrofobicidade, o que é perfeito para formação de nanoemulsão. Logo após a Base de Schiff foi iodada. As estruturas, tanto lipídicas como a Base de Schiff com acoplamento com cadeia de sete carbonos e a estrutura iodada, tiveram suas capacidades de absorção de raio-x medidas no aparelho IVIS® LUMINA XR Series III. A base de Schiff iodada demonstrou uma capacidade de absorção de raio-x de cerca de 2,17 vezes maior que a água demonstrando ser excelente para a finalidade proposta. A base de Schiff iodada com cadeias C7 nanoemulsionada obteve a absorção de raio-x de cerca de 1,22 vezes maior que a água. O acoplamento com cadeias C7 à base de Schiff trouxe a inversão da densidade do óleo fazendo com que esta se tornasse mais pesado que a água provavelmente devido ao alto peso molecular conferido a base de Schiff com o acoplamento. A partir dos resultados obtidos foi observado que a base de Schiff iodada acoplada com cadeias C7 e nanoemulsionada é promissora como agente de contraste necessitando tão somente testes in vivo para completa certificação de um novo tipo de agente de contraste nanoemulsionado no mercado.<br>Due to the current iodinated contrast agents cause many adverse effects and not offering imaging for a period longer than thirty minutes, there is a need for the search for contrast agents that reduce the adverse effects and conducive to long-term imaging. Therefore the development of a nanostructured iodinated contrast agent becomes promising since their nano structure in itself brings the reduction of adverse effects, and this allows to control the time that the contrast agent remains in the body thereby providing a longer imaging. The objective of this study was to develop a new formulation containing nanostructured iodinated contrast agents for use in computed tomography using two synthetic routes, one with nanostructured lipid carriers, which subsequently proved to be impracticable, and another synthetic route was the use of Schiff Bases which proved to be promising. The Schiff bases had their characteristics evaluated for their preparation, iodination thereof, coupling of carbon chains to give to these lipid solubility and obtaining of X-ray image by IVIS® LUMINA XR Series III machine. The Schiff base iodinated showed an x-ray absorbing capability to approximately 2,17 times greater than the water proving to be excellent for the proposed purpose. The coupling of the C7 chains brought to the Schiff base a density inversion of the oil causing it to become heavier than water probably due to the high molecular weight given to Schiff base with the coupling. This coupled Schiff sample was taken to IVIS® LUMINA XR Series III (28 Kv 100 uA) and had demonstrated its large absorption by x-ray which shows be great for a contrast agent. The Schiff base with iodine and coupling C7 was nanoemulsioned and tested in by IVIS® LUMINA XR Series III (28 Kv 100 uA) and demonstrated x-ray absorption but not as intensely as the Schiff base iodine C7 not nanoemulsioned, probably due to the dilution that the nanoemulsion suffered. From the results obtained it was observed that the Schiff base iodinated coupled with C7 and nanoemulsioned is promising as a contrast agent requiring solely in vivo tests for full certification of a new type of contrast agent in the market nanoemulsioned.

In this dissertation, research efforts mainly focused on exploring the applications of superparamagnetic iron oxide nanoparticles (SPIONs) in MR imaging and nanocatalysis via surface functionalization. A dopamine-based surface-functionalization strategy was established. The Simanek dendrons (G1 to G3), oligonucleotides and amino acids were loaded onto SPION surfaces via this approach to develop pH-sensitive MRI contrast agents, specific-DNA MR probes and a biomimetic hydrolysis catalyst. Dendron-SPION conjugates (G1 to G3) have good aqueous solubilities and high transverse relaxivities (>300 s-1*mM-1). They also showed interesting strong pH-sensitive R2 and R2* relaxivities, which were governed by the clustering states of dendron-SPIONs in different pH environments. Values of R2m and R2* m/R2m varied by over an order of magnitude around pH 5. The efficient cell-uptake (~3 million/cell) and low cytotoxicity of G1 to G3-SPIONs were demonstrated on HeLa cell cultures. The strong R2* effects were observed indicating the SPION clustering in HeLa cells. Two SPION-oligonuleotide conjugates were synthesized by coupling two half-match oligonucleotides onto domapine-capped SPIONs via SPDP linkers. They served as MR probes to detect a single-strand DNA with the same sequence to miRNA-21 based on the change of R2 values due to the DNA-bridged SPION clustering. The detection limit of the DNA could reach to 16.5 nM. A biomimetic hydrolysis nanocatalyst (i.e., Fe2O3-Asp-His complex) was developed by loading Asp and His-dopamine derivatives onto SPIONs. Paraoxon and nitrophenyl acetate were hydrolyzed under a mild condition (neutral pH, 37 °C) catalyzed by the Fe2O3-Asp-His complex. The two amino acids Asp and His cooperated with each other on the SPION surfaces to catalyze hydrolysis reactions. This catalyst could be recycled by a magnet and reused for four times without a significant loss of catalytic activity.

Advanced optical imaging techniques are emerging as useful ways to screen tissues for the presence of cancer. Plasmon resonant nanoparticles have unique optical properties that make them ideal for use as optical contrast agents. The capacity of these particles to serve a multifunctional role dependent on their composition and the intensity of incident light enables them to serve as diagnostic tools and to provide the therapeutic capability of photo-thermal energy conversion or the controlled release of an encapsulated agent. Likewise, the ability to degrade into components of a clearable size may enable the clinical translation of these types of particles.These properties were demonstrated by means of experiments in the support of three specific aims. The first specific aim was to determine whether the unique and tunable optical properties of nanorods lend them to generate signal in advanced optical imaging techniques, and that nanorods can facilitate photo-thermal conversion. The second specific aim was to show that liposomes can serve as a scaffold for the support of an array of gold nanodots to generate a structure that exhibit tunable plasmon resonant characteristics and a resultant ability to generate signal in optical imaging techniques while having the capability to degrade into inert particles of a size that can be readily cleared from the body via the kidney. The final specific aim was to determine whether the gold-coated liposomes of the second specific aim can serve as system for light-based delivery of an encapsulated agent in addition to its role as an optical contrast agent and its biodegradation capacity.Plasmon resonant nanorods and plasmon resonant gold-coated liposomes were generated by reducing free gold from solution onto surfactant coated seed particles and phospholipid liposomes, respectively. Both structures demonstrated the ability to generate signal in optical coherence tomography and in multi-photon confocal microscopy images. Nanorods in high intensity light demonstrate a capacity to mediate photo-thermal energy conversion. While, in similar conditions, gold-coated liposomes are shown to release their contents. Gold-coated liposomes are also shown to degrade to bioinert components of a size reasonable for rapid renal clearance using either surfactant or enzyme.

L’objectif de ce travail fut de développer et d’appliquer des technologies avancées de mélange et d’émulsification pour la préparation de nanovecteurs de morphologies complexes potentiellement utilisables en tant que produits pharmaceutiques. Premièrement, un procédé de nanoprécipitation assisté par micromélangeur fut utilisé pour obtenir et contrôler la taille de nanoparticules de PMMA chargées en Kétoprofène (100-200 nm). Combiné avec un appareil de séchage par pulvérisation, des nanoparticules sèches purent être obtenues dont les propriétés physico-chimiques furent proches de celles des particules non séchées. Ce microprocédé de nanoprécipitation permit également d’encapsuler des nanoparticules d’oxyde de fer (6 nm) dans des nanoparticules de PMMA de 200 nm avec une fraction massique de 60%. Pour augmenter la fraction solide de ces nanosuspensions et obtenir des particules sphériques de tailles plus petites (100 nm), une méthode de nanoémulsification basée sur un fort écoulement élongationnel fut employée. Deuxièmement, des émulsions et nanohydrogels doubles encapsulant un médicament hydrophile modèle dans leur cœur aqueux furent obtenus par couplage d’un microfluidiseur commercial pour l’obtention de l’émulsion primaire et d’une méthode d’émulsification basse énergie (émulsification spontanée) pour la double émulsification. La taille des nanovecteurs doubles a pu être variée grâce au rapport massique surfactant/huile (SOR) dans la gamme 80-80 nm. La colocation de deux sondes fluorescentes, placées dans le cœur et dans l’écorce, a pu être confirmée par microscopie confocale en fluorescence. La méthode d’émulsification spontanée fut également employée pour produire des nanolipogels (60 nm) chargées ou non de nanoparticules d’oxyde de fer et d’or (6 nm)<br>The aim of this work was to develop and apply advanced technologies in mixing and emulsification for the preparation of morphologically-complex nanocarriers for potential uses in pharmaceutics. Firstly, a micromixer- assisted nanoprecipitation process was used to get and to easily tune the size of Ketoprofen-loaded PMMA nanoparticles (100-200 nm). Combined with a commercial spray dryer, dry-state drug-loaded polymeric nanoparticles (NPs), which main physicochemical properties were close to those of non spray-dried NPs, were successfully produced. This nanoprecipitation microprocess also allowed encapsulating 6 nm iron oxide NPs into 200 nm PMMA nanoparticles with a weight ratio of 60%. To increase the solid content of the above nanosuspension and get spherical polymeric NPs of smaller sizes (100 nm), an elongational-flow nanoemulsification method was used. Secondly, double nanoemulsions/nanohydrogels encapsulating a hydrophilic model drug in the aqueous core droplets/hydrogel were obtained by the combination of a commercial microfluidizer for the primary emulsion and a low energy emulsification method (spontaneous emulsification) for the double emulsification. The size of the double nanocarriers was varied by means of the surfactant to oil ratio (SOR) in the range 80 to 180 nm. Colocation of two fluorescent probes located in the core and in the shell was confirmed by fluorescence confocal microscopy. The spontaneous emulsification method was also employed to produce nanolipogels whose size could be tuned down to 60 nm. These nanolipogels were also loaded with iron oxide nanoparticles (6 nm) or gold nanoparticles (6 nm)

2013/2014<br>The main purpose of this thesis work is the investigation of the role of the glassy state on the Dynamic Nuclear Polarization (DNP) process, paying particular attention to the application in the diagnostic field (Magnetic Resonance Imaging, MRI). So far, experimental evidences have shown that the crucial requests for a sample containing paramagnetic impurities to be polarized by DNP are its amorphous state and the homogeneity of its glassy mixture and dispersion. On the other hand, a consistent theoretical interpretation for this phenomenon is missing, as well as a deep analysis on the “goodness” of the glassy state obtained after the amorphization process, intended for DNP-MRI application. An alternative preparation procedure of contrast agents containing radical molecules, hyperpolarizable by DNP, is proposed in this thesis. The novelty of these glassy samples is that they are solid at room temperature. Under these circumstances, a methodology of characterization of the amorphous solids in all the fundamental aspects (thermal, spectroscopic, structural and magnetic properties) is suggested to investigate the correlation between the glassy state and the hyperpolarization features (such as the maximum achievable value of polarization, P%). In particular, in this way it is possible to study one of the main problems in this topic, that is the effect of the presence of nano- and micro-crystalline domains on the homogeneity of the radical distribution and, then, on the efficiency of the magnetic polarization transfer. Furthermore, in order to optimize the DNP efficiency, another crucial issue is the role of the radical concentration on the polarization transfer and whether high concentration could lead to either quenching effect or to radical aggregation. For this purpose, several amorphization procedures of solids have been analyzed. This study shows that co-milling is the best procedure, that provides riproducibility, prevents degradation and allows a good control of the physical features of the glass and of the crystalline phase. A milled mixture of trehalose and TEMPO molecules has been chosen as model system, because of the high stability of trehalose and high solubility of the TEMPO radical. Chapters 1 and 2 briefly report the state of art regarding both the glassy state and the preparation of amorphous samples, addressing to the issue relevant for the hyperpolarization by DNP in chapter 2. Chapter 3 presents a discussion about the choice of the optimal combination of amorphization technique and model system. The characterization of the model system perfomed by Differential Scanning Calorimetry (DSC), Electron Paramagnetic Resonance (EPR), Solid State Nuclear Magnetic Resonance (SSNMR) and Raman spectroscopies and X-Ray Diffraction (XRD) is described in chapter 4. The effects of both the concentration and the amorphization degree on the physical properties of the samples have been highlighted. Chapter 5 reports results of DNP measurements on the model system. The effect of radical concentration on the polarization transfer has been stressed for fully amorphized samples (12 h of milling), paying attention to the physical stability of these amorphous solids. In addiction, some alternative substrates used in DNP-MRI have been tested for comparison. In the final part of this work, chapter 6 describes an ancillary study on the dehydration of solutions, carried out by means of a novel calorimetric approach to investigate the role of water (possibly absorbed from the environment) on the stability of the amorphous solids. Further investigation in this direction is needed. For example, direct comparison between EPR spectra and DNP enhancement, as well as a deep analysis of the TEMPO-trehalose and TEMPO-TEMPO interactions by mean of vibrational spectroscopy could allow to investigate aggregation processes in high concentration samples. Moreover, further studies of dynamic properties by mean SSNMR would allow to separate the behaviour of the crystalline and amorphous phases and to follow separately the two processes, amorphization and co-mixing, that simultaneously occur during the milling. Furthermore, FT analysis of the obtained XRD patterns will provide information on the spatial distribution of the molecules of trehalose (and TEMPO) by deriving the pair distribution function, g(r). Finally, the methodology of investigation above described opens a new avenue to characterize the effect of the matrix density of aged glasses or of controlled dispersion of nanocrystals into the amorphous matrix on the DNP performance, from both experimental and theoretical approches. A more systematic analysis of the DNP measurements could be carried out, in order to have more information on the correlation between the presence of crystals and the efficiency of the magnetic transfer: in particular, the maximum dimension of the crystalline domains and the maximum achievable polarization are the parameters that should be correlated.<br>Lo scopo principale di questo lavoro d tesi è lo studio del ruolo dello stato vetroso sul processo di Polarizzazione Nucleare Dinamica (DNP), prestando particolare attenzione all'applicazione in campo della diagnostica per immagini di Risonanza Magnetica (MRI). Finora, evidenze sperimentali hanno dimostrato che le caratteristiche cruciali di un campione contenente impurezze paramagnetiche per poter essere polarizzato tramite DNP sono rappresentate dal suo stato amorfo e dalla omogeneità della sua miscela e dispersione vetrosa. D'altra parte, mancano ancora sia una interpretazione teorica coerente di questo fenomeno che una una approfondita analisi sulla "bontà" dello stato vetroso per applicazioni DNP-MRI preparato a seguito di un processo di amorfizzazione. In questa tesi viene proposta una procedura alternativa per la preparazione di agenti di contrasto contenenti molecole di radicali iperpolarizzabili tramite DNP. La novità di questi campioni vetrosi è che sono solidi a temperatura ambiente. In queste condizioni, viene proposta una metodologia di caratterizzazione di solidi amorfi nei vari aspetti fondamentali (termici, spettroscopici, strutturali e magnetici) allo scopo di indagare la correlazione tra proprietà dello stato vetroso e caratteristiche di iperpolarizzazione (ad esempio, in quali condizioni è possibile raggiungere il valore massimo di polarizzazione P%). In tal modo è possibile studiare uno dei principali problemi in questo argomento, ossia l'effetto della presenza di domini nano- e micro-cristallini sulla omogeneità della distribuzione di radicali e quindi sulla efficienza di trasferimento di polarizzazione magnetica. Inoltre, al fine di ottimizzare l’efficienzadel processo di DNP, un altro problema cruciale è comprendere il ruolo della concentrazione di radicale sul trasferimento di polarizzazione e se una alta concentrazione può portare ad un effetto di spegnimento o di aggregazione di radicali. A questo scopo, sono state analizzate diverse procedure di amorfizzazione di solidi; la co-macinazione è risultata essere la procedura migliore in quanto permette di preparare campioni con caratteristiche riproducibili, ne previene la degradazione e consente un buon controllo delle caratteristiche fisiche del vetro e della fase cristallina. Una miscela macinata di molecole trealosio e TEMPO è stato scelto come sistema modello, grazie alla elevata stabilità di trealosio e alla elevata solubilità del radicale TEMPO. I capitoli 1 e 2 riportano brevemente lo stato dell'arte per quanto riguarda sia stato vetroso e la preparazione di campioni amorfi, affrontando il problema rilevante della iperpolarizzazione tramite DNP nel capitolo 2. Il capitolo 3 presenta una discussione sulla scelta della combinazione ottimale costituita da tecnica di amorfizzazione e sistema modello. La caratterizzazione del sistema modello tramite Calorimetria a Scansione Differenziale (DSC), Risonanza Paramagnetica Elettronica (EPR), Risonanza Magnetica Nucleare a Stato Solido (SSNMR), Spettroscopia Raman e Diffrazione ai Raggi X (XRD) è descritta nel capitolo 4. Tali misure hanno permesso di evidenziare gli effetti della concentrazione e del grado amorfizzazione sulle proprietà fisiche dei campioni. Il capitolo 5 riporta i risultati delle misure DNP sul sistema modello. L'effetto della concentrazione di radicali sul trasferimento di polarizzazione è stato investigato su campioni completamente amorfizzati (12 h di macinazione), prestando particolare attenzione alla stabilità fisica di questi solidi amorfi. Inoltre, alcuni substrati alternativi già utilizzati in DNP-MRI sono stati testati per un confronto. Nella parte finale di questo lavoro, il capitolo 6 descrive uno studio ausiliario sulla disidratazione di soluzioni effettuata mediante un nuovo approccio calorimetrico per studiare il ruolo di acqua (eventualmente assorbita dall'ambiente) sulla stabilità dei solidi amorfi. Per uno sviluppo di questo studio sono necessarie ulteriori indagini in questa direzione. Ad esempio, il confronto diretto tra spettri EPR e di aumento del segnale DNP, nonché di una profonda analisi delle interazioni TEMPO-trealosio e TEMPO-TEMPO tramite spettroscopia vibrazionale potrebbero consentire di investigare i processi di aggregazione operativi in campioni ad alta concentrazione. Inoltre, ulteriori studi di proprietà dinamiche tramite SSNMR dovrebbero permettere di separare il comportamento dellle fasi amorfa e cristallina e di seguire separatamente i due processi, amorfizzazione e co-miscelazione, che si verificano simultaneamente durante la macinazione. Inoltre, l'analisi FT dei segnali XRD potrà fornire informazioni sulla distribuzione spaziale delle molecole di trealosio (e TEMPO) derivando la funzione di distribuzione, g(r). Infine, la metodologia di ricerca sopra descritta apre una nuova via per caratterizzare l'effetto della densità della matrice di vetri invecchiati o di dispersioni controllate di nanocristalli nella matrice amorfa sulle prestazioni DNP tramite approcci sia teorici che sperimentali. Potrebbe essere effettuata una analisi più sistematica delle misure DNP, in modo da avere ulteriori informazioni sulla correlazione tra la presenza di cristalli e l'efficienza del trasferimento magnetico: in particolare, la dimensione massima dei domini cristallini e la polarizzazione massima ottenibile sono i parametri che devono essere correlati.<br>XXVII Ciclo<br>1985

Gold nanoparticles (Au NPs) always fascinated the scientific community, demonstrating several applications in nano-medicine, due to the peculiar properties of this metal at the nano-metric scale. First of all, gold is characterized by a strong inert nature, resisting to the air oxidation and corrosion. This chemical non-reactivity is correlated to a bio-inert nature of the metal that makes it an outstanding candidate for the development of in vitro and in vivo devices. Despite this great inertness, Au can form stable bonds with sulphur containing compounds, like thiols or disulfides. Exploiting this kind of chemistry is possible to easy and robustly functionalize Au NPs with different types of polymers, bio-molecules or targeting moieties. Moreover, Au NPs possess fascinating optical properties like localized surface plasmon resonance (LSPR), photoluminescence, enhancement of Raman signals and elevated X-rays attenuation. By tuning the Au NPs size, shape, coating, labelling and active targeting it is possible to obtain designed platforms acting as therapeutic, diagnostic or theranostic agents. In the present thesis are investigated three fundamental aspects correlated with the employment of gold nanoparticles in biomedicine. Au NPs, thanks to the high density and atomic number, present an elevated X-ray absorption coefficient. These NPs, if properly functionalized, can act as effective CT contrast agent and can be easily visualized by mean of in vivo micro-CT analysis. Here in is reported a methodology for the synthesis of highly stable and functionalized Au. The presented method allowed us to tune the surface coatings and the morphology of the Au NPs, designing a “one-pot” synthesis of engineered isotropic and anisotropic nanoparticles. The present study is devoted to elucidate the major factors involved in the in vivo biodistribution of PEGylated Au NPs. The effects of NPs structural parameters (eg. charge, shape and dimension) on the circulation time in the blood pool were analysed. From this study, we derived interesting information, generally applicable to the design of different types nano-structured contrast agents. Furthermore, other two fundamental topics involved in the design of effective nano-structured contrast agents has been investigate: the nanoparticles renal clearance and the active targeting toward inflamed tissues. Moreover, in the present thesis is investigated the interaction of surface functionalized Au NPs with the biological matter. When nanoparticles come in contact with biological materials, bio-molecules are adsorbed on their surface. This phenomenon causes a modification the identity of the systems and an uncontrolled aggregation of the NPs. The investigation of this phenomenon is fundamental to understand both the intracellular dynamics and the physiological behaviour of the nanoparticles. It is essential to consider these factors in the design of nano-systems effectively applicable in the biomedical field. In particular, in the present study, Fluorescence Correlation Spectroscopy (FCS) has been exploited to acquire information on the diffusion times of surface functionalized Au NPs, both in protein solution and in living cells. In the last chapter is investigated a more technical issue, related to the nanoparticles synthesis. In order to think to a reliable application of the nanotechnologies in the biomedical field, innovative synthetic procedure needs to be identified, to ensure a scale up and higher reproducibility of the production. A fluidic manufacturing method for the production of structurally controlled Au NPs was developed. Fluidic chemistry is a promising technology that can address to the scale up and reproducibility issues that affect the nano-materials production. The presented manufacturing method demonstrated to be strongly versatile, allowing the one-pot production of nano-materials with controlled shape, and engineered surface, readily applicable in a vast number of fields.

碩士<br>國立清華大學<br>電機工程學系<br>100<br>Photoacoustic (PA) imaging requires contrast agents which can enhance the contrast and efficiency of tumor targeting, own high thermal stability and long circulation time, and are effective in low doses in vivo. In this study, we developed magnetic porous nano-silica beads with pore-filled gold nanorods (FeAuNSBs) as a multi-functional contrast agent of photoacoustic imaging. It owns the merits of gold nanorods with silica coating – high biocompatibility, PA signal amplification and optical tunability for PA signal generation. The magnetic property of its embedded iron oxide is used to improve tumor targeting, i.e., magnetic targeting. Phantom experiments were performed to confirm the tunability of FeAuNSB’s optical absorbance in near-infrared light, which ranges from 600-900nm, which allows us to avoid the interference of blood. Experiments with exposure of the phantom to laser pulses demonsrated the higher photothermal stability of FeAuNSBs. The wavelength of peak optical absorption was also sustained. The magnetic targeting property of FeAuNSBs enhanced the contrast in tumor regions by approximately 17 dB. It was also found that the FeAuNSB aggregation caused by magnetic targeting increased the contrast in ultrasound imaging. The in-vivo experimental results showed that with the magnet targeting to a tumor, we obtained a high contrast increase of about 10 dB over the targeted region in PA and US images, which is higher than 2 dB achieved using conventional AuNRs. Overall, we proved the feasibility of FeAuNSBs as a good tumor targeting contrast agent of PA imaging. Future work will focus on verification of FeAuNSB’s performance on photothermal therapy with PA image guidance.

Cardiovascular diseases represent the leading cause of mortality and disability worldwide. Besides, it is estimated that these numbers will increase significantly in the future. More specifically, atherosclerosis is present in most of the main cardiovascular diseases, making its study urgent and important to develop new diagnostic tools. The most relevant limitation in the current investigation of the evaluation of atherosclerosis is the impossibility to distinguish stable and prone to rupture (unstable) plaques in coronary arteries. Associated with the instability phenomena, in plaques prone to rupture, are increased thickness of tissue layers (already detectable but not provide an unequivocal diagnosis) and inflammatory processes (not yet detectable but only present when the lesion evolves higher risk to rupture). Aiming to detect the precise location of inflammatory processes, two types of contrast agents (nano probes) were synthetized, gold nanoparticles and microbubbles. Also, to replicate the behavior of human arteries, three-dimensional tissue simulating structures (phantoms) were fabricated and optimized. To evaluate the performance of the contrast agents, both in the phantoms and post-mortem human arteries, optical coherence tomography (OCT) images were acquired in a clinical environment, and other techniques were performed (confocal microscopy, scanning electron microscopy, atomic force microscopy) to characterize the samples. Microbubbles revealed to be a better contrast agent than gold nanoparticles having a clearly noticeable enhancement of the OCT signal. After the acquisition of several OCT images on both types of samples (arteries and phantoms) an automatic imaging processing software was developed to detect the presence of the contrast agents and its posterior location. The software uses MATLAB as a programming language and with a user-friendly interface the user can access numerous parameters of the analyzed image and even edit them manually. In the end of the automatic processing, the user has the information of the number of regions of interest as well as their visual location.

碩士<br>慈濟技術學院<br>放射醫學科學研究所<br>102<br>Abstract In this study, Fe3O4 magnetic nanoparticles was prepared by using chemical co-precipitation method andcoated with surfactant dextran which containingthe bio-compatible and chemically stable effects. It were also investigated for the influence of various parameters on the heating conditions and T2 signal intensity. According from the experimental results, it was obtained the excellent purity of Fe3O4 under optimal condition, which are 90℃ ± 5℃ of reaction temperature, 10〜12 of pH value; 2 hours of reaction time, respectively. Dextran was coated under optimal condition, which are 80℃ ± 5 ℃ of reaction temperature; 2 hours of reaction time, respectively. By using 80KHz of high frequency heating and 3T MRI scanning, it were obtained the comfortable heating rateeffect and T2 signal gain image. Fe3O4 magnetic nanoparticles was compared with Fe3O4 magnetic nanoparticles with dextran-coating (Fe3O4@dextran)by using one-step and two-step synthetic pathway for MRI contrast agent and hyperthermia evaluation In this work. The Fe3O4@dextran of two-step process is relatively time-consuming but more complete crystal structure, and achieving better T2 heating efficiency and strong signal change. Five samples by two-step process were stored under temperature 4℃, 22℃ and 37℃ under staying to seven days, displayed high stability without agglomeration. In the other way, Fe3O4@dextran by one-step process also obtained more stabilities without agglomeration than those by two-step processat different range of reaction temperature and storing time. T2 signal intensity of 3T MRI scan for Fe3O4 magnetic nanoparticles, Fe3O4@dextran by one-stepprocessand two-step process were 58.6 s-1, 45.2 s-1and 8.1s-1, respectively. They allshowed the significant inhibitory effect. Using mouse monocytes (RAW) and human breast cancer cells (MDA) conducting MTT cell viability test for toxicity studies, the normal monocytes showed toxic effects of low damage, and the breast cancer cells produced little toxicity, but cell survival can be maintained at above 80% for Fe3O4 magnetic nanoparticles, but they were obtained more than 90% fraction of cell survival for two Fe3O4@ dextran samples. Besides, magnetic nanoparticles with high frequency heating are harmful to human breast cancer cells, and decreased heavily to 9%of cell survival for Fe3O4 magnetic nanoparticles, and 7% of cell survivalwas found for Fe3O4@dextran by two-step process. The treatment effect were very significant. Based on the experimental results, the magnetic nanoparticles were successfully prepared with dextran-coated. The Fe3O4@ dextran by using one-step and two-step synthetic pathway, showed the good bio-compatibility, cytotoxicity reduction and particle stability. They can effectively be converted into heat energy to treat human breast cancer cells, and show the good T2 contrast imaging. In conclusion, the magnetic nanoparticles play a key role and potential due to their unique features as heating mediators for hyperthermia and constract agents for clinic MRI study.