Dissertations / Theses on the topic 'Nanocarrier Liposoma'

The invasive nature of glioblastoma (GBM) represents a significant challenge to the standard of care and contributes to poor clinical outcomes. Invasion of tumors into healthy brain restricts chemotherapeutic access and complicates surgical resection. The central hypothesis of the thesis is that an effective anti-invasive agent can enhance the standard chemotherapeutic response in invasive brain tumors. Through a screen of novel compounds, a new anti-invasive small molecule, Imipramine Blue (IB), was identified. This triphenylmethane compound inhibits invasion of highly invasive glioma in vitro and in vivo. To elicit a response in vivo, Imipramine Blue was liposomally encapsulated to yield better delivery to tumor. Using this formulation, it is shown that IB attenuates invasion of glioma in vivo leading to a more compact tumor in an aggressively invasive rodent glioma model. Further, it is shown that this novel compound binds NADPH oxidases and alters expression of actin regulatory elements to elicit this anti-invasive activity. To test our hypothesis that anti-invasive therapy coupled with chemotherapy will enhance efficacy, nano-IB therapy was followed by liposomally encapsulated doxorubicin (DXR) chemotherapy. Additionally, a co-encapsulated formulation of IB and DXR was developed and tested in vivo. This combination therapy significantly enhanced survival compared to IB or DXR alone, resulting in long-term survival in the syngeneic invasive rat astrocytoma model RT2. It was seen that sequential treatment was more effective than the co-encapsulated treatment indicating a benefit of pre-treating the tumor with the anti-invasive. This thesis demonstrates that novel anti-invasive IB mediated 'containment' of diffuse glioma significantly enhances the efficacy of DXR chemotherapy compared to chemotherapy or anti-invasive therapy alone.

The functional and morphological alterations of the vascular endothelium of the lymphatic system, the micro-environmental alterations such as the amplification of the enzyme kit, the overexpression of specific receptors, the increase in the redox potential, temperature and the lowering of the pH, are typical characteristics of tumor tissues. These features can be exploited successfully for the development of suitable supramolecular and colloidal systems with passivelly and activelly guided delivery of anticancer drugs at the site of action. Here we aimed at investigating a novel pH responsive liposomal platform to achive selective tumor targeting to ensure the accumulation of the drug in adequate therapeutic concentration. Liposomes were decorated with a novel non-peptidic cell penetrating enhancer (CPE) that simulates the action of the natural peptides known from the literature studies. A synthetic procedure was developed to obtain a oligoarginyl-dendron derivative to be included in the lipid bilayer of the liposomes. The derivative TetraBoc-Arg(pbf)-[G-2]-distearoyl glycerol (Arg4-DAG) consists of a central polyester core to which arginines were conjugated on one side and that was terminated with a distearoyl glycerol chain on the other. The resulting macromolecule possesses a amphiphilic character in virtue of its two combined moieties: 1) the hydrophobic distearoyl tail acting as lipidic anchor for lipid bilayer association , 2) the positively charged peripheral arginines, which provides for high cationic density and mimic the basic aminoacid residues of TAT peptide, thus conferring the biological activity to the system. The intermediates and the final product were characterized by 1H, 13C NMR and mass spectrometries. Liposomes obtained with a 2:1 HSPC/cholesterol molar ratio were generated with increasing ratio of the CPE with respect to lipids using the post insertion technique which provided for the increase of liposome zeta potential from +8 mV to +24 mV as the ratio of CPE increased from 1% to 4%, then reaching a plateau. The biological properties of fluorescently labelled CPE coated liposomes were investigated on HeLa cancer cells. Flow cytometry analysis and confocal microscopy study confirmed the high capacity of the liposomes to associate with cells. A 30 times higher efficiency of cancer cell association was found with respect to naked liposomes. The CPE coated liposomes demonstrated a remarkable ability to deliver in the cytosol albumin and calcein. BSA was chosen as protein model, whereas calcein was selected because it is a strongly hydrophilic molecule, so as to mimic the behavior of water soluble drugs. Both molecules were incorporated into the hydrophilic core of liposomes. The calcein was not release from the liposomes for at least 16 days, whereas BSA was completely released in 7 days. In order to confer to liposomes sensitivity to pH alterations for controlled access to cancer cells, a pH sensitive polymer of mPEG-oligosulphadimethoxine (mPEG5kDa-SDM8) was synthesized by radical polymerization of sulfadimethoxine methacrylate from 2-bromo-isobutyryl-methoxyPEG (mPEG-Br) 5kDa. mPEG5kDa-SDM8 possesses a pKa of 7.12 which ensures a deprotonated state with negative charge at physiological pH (7.4) and a protonated neutral state at pH 6.5, which corresponds to the tumor environment. Zeta potential analysis performed on Arg4-DAG coated liposomes decorated with the mPEG5kDa-SDM8 polymer confirmed that the most finely regulated shielding/unshielding capacity is obtained when the two modules are equimolar, both at 4% in moles with respect to lipids. This formulation was found to be stable even in the presence of serum proteins, which does not alter the charge-to-charge interaction between the oligo-sulfadimethoxine of the pH responsive polymer and oligo-arginines of the CPE as observed by zeta potential analysis. The SPR study also confirmed this result, proving the polymer association with the CPE coated liposomes at pH 7.4 and the release at pH 6.5 mimicking the tumor, which corresponds to a sheddable physical PEGylating under controllable conditions. Finally, the biological studies confirmed the ability of the pH responsive polymer to shield the CPE on the liposomal surface under physiological conditions (pH 7.4), which prevents the internalization of both the unloaded pH responsive vesicles, and the calcein loaded vesicles, whereas revealing it when exposed to tumor mimicking acid environment, allowing for liposome cell entry and payload intracellular delivery.
Alterazioni funzionali e morfologiche dell'endotelio vascolare del sistema linfatico, alterazioni micro-ambientali quali l'amplificazione del kit enzimatico, sovraespressione di recettori specifici, aumento del potenziale redox, temperatura e abbassamento del pH, sono caratteristiche tipiche dei tessuti tumorali. Queste caratteristiche possono essere sfruttate con successo per lo sviluppo di sistemi colloidali sopramolecolari in grado di direzionare passivamente o attivamente farmaci antitumorali al sito d'azione. In questo lavoro è stata indagata una nuova piattaforma liposomiale sensibile al pH per il direzionamento selettivo al tumore e assicurare l'accumulo del farmaco in concentrazione terapeutica adeguata. I liposomi sono stati decorati con un nuovo promotore di internalizzazione cellulare non-peptidico che simula l'azione dei peptidi naturali conosciuti dagli studi di letteratura. È stata messa a punto una nuova procedura di sintesi per ottenere il derivato dendronico oligoargininico da includere nel doppio strato lipidico dei liposomi. Il derivato TetraBoc-Arg (PBF) - [G-2] -distearoil glicerolo (Arg4-DAG) è costituito da un nucleo centrale di poliestere a cui le arginine sono state coniugate su un lato e che è stato terminato con una catena distearoil glicerolo dall'altro. La macromolecola risultante possiede un carattere anfifilico in virtù delle sue due frazioni combinate: 1) la coda idrofoba distearoil, elemento lipidico di ancoraggio per associazione al doppio strato lipidico, 2) la carica positiva conferita dalle arginine periferiche, che mimano i residui amminoacidici fondamentali del peptide TAT, conferendo così l'attività biologica del sistema. Gli intermedi e il prodotto finale sono stati caratterizzati da 1H, 13C NMR e spettrometria di massa. I liposomi ottenuti con un rapporto molare 2:1 HSPC/colesterolo sono stati generati con crescente rapporto del CPE rispetto ai lipidi, utilizzando la tecnica di ‘post-insertion’, che ha determinato l'aumento del potenziale zeta dei liposomi da +8 mV a +24 mV, all’aumentare del rapporto di CPE dall'1% al 4%, raggiungendo quindi il plateau. Le proprietà biologiche dei liposomi rivestiti con il CPE fluorescente sono state studiate su cellule tumorali HeLa. L’analisi citofluorimetrica e lo studio di microscopia confocale hanno confermato l'elevata capacità dei liposomi di associare con le cellule. Rispetto al liposomi nudi, è stata rilevata una maggiore efficienza di associazione alla cellula tumorale di 30 volte. I liposomi rivestiti col CPE hanno dimostrato una notevole capacità di veicolare albumina e calceina nel citosol. BSA è stata scelta come proteina modello, mentre calceina è stata scelta perché è una molecola fortemente idrofila, in modo da simulare il comportamento di farmaci idrosolubili. Entrambe le molecole sono state incorporate nel nucleo idrofilo di liposomi. La calceina non è stata rilasciata dai liposomi per almeno 16 giorni, mentre BSA è stata completamente rilasciata in 7 giorni. Al fine di conferire ai liposomi responsività ad alterazioni di pH per l'accesso controllato alle cellule tumorali, è stato sintetizzato un polimero sensibile, pH mPEG-oligosulphadimethoxine (mPEG5kDa-SDM8), mediante polimerizzazione radicalica di sulfadimetossina metacrilato su una catena di 2-bromo-isobutirril-methoxyPEG (MPEG-Br ) 5kDa. mPEG5kDa-SDM8 possiede un pKa di 7,12 che garantisce uno stato deprotonato con carica negativa a pH fisiologico (7.4) e uno stato neutro protonato a pH 6,5, che corrisponde all'ambiente tumorale. L’analisi di potenziale Zeta eseguita su liposomi decorati con Arg4-DAG e con il polimero mPEG5kDa-SDM8 ha confermato che la capacità di schermatura/deschermatura più finemente regolata si ottiene quando i due moduli sono equimolari, entrambi a 4% in moli rispetto al lipidi. Questa formulazione è risultata stabile anche in presenza di proteine ​​del siero, che non alterano l'interazione carica-carica tra l'oligo-sulfadimetossina del pH del polimero reattivo e oligo-arginine del CPE come osservato mediante analisi potenziale zeta. Anche lo studio SPR ha confermato questo risultato, dimostrando l'associazione del polimero con i liposomi rivestiti col CPE a pH 7.4 e il rilascio a pH 6,5, che corrisponde ad una peghilazione fisica reversibile in condizioni controllabili. Infine, gli studi biologici hanno confermato la capacità del polimero pH sensibile di schermare il CPE sulla superficie liposomiale in condizioni fisiologiche (pH 7,4), che impedisce l'internalizzazione delle vescicole non responsive al pH sia non caricate, sia caricate con calceina, mentre il polimero espone il CPE sulla superficie dei liposomi in presenza di un ambiente acido che simula il tumore, consentendo l'ingresso ai liposomi nelle cellule e la veicolazione del loro contenuto a livello intracellulare.

Existing methods of treating glioma are not effective for eradicating the disease. Therefore, new and innovative methods of treatment alone or in combination with existing therapies are necessary. Delivery of therapeutic agents through delivery carriers such as liposomes diminishes the harmful effects of the agent in healthy tissues and allows increased accumulation in the tumor. In addition, targeted chemotherapy using liposomes provides the opportunity for further increase in drug accumulation in tumor. However, the current targeting strategies suffer accelerated plasma clearance and are not advantageous in improving efficacy. The search for new tumor targets, novel ligands, new strategies for targeting, and particle stabilization will advance our ability to improve delivery at the tumor level while decreasing toxicity to normal tissues. The global objective of this thesis was to improve the status of current liposomal therapy to achieve higher efficacy in tumors. Here, we show a novel mechanism to increase targeting to tumor while uncompromising on the long circulation of stealth liposomes. Long circulation is essential for passive accumulation of the nanocarriers due to EPR effect, in order to see benefits of targeting. Using phage display technique, a variety of tumor specific peptides were identified for use as targeting moieties. One potential advantage of the approach proposed here is the rapid identification of patient tumor specific peptide that evades the RES. This could lead to the development of a nanocarrier system with high avidity and selectivity for tumors. Therefore, tumor accumulation of the targeted formulations will be higher than that of non‐targeted liposomes due to increased drug retention at the tumor site and uncompromised blood residence time.In addition, it has been shown that the distribution of nanocarriers, spatially within the tumor, is limited that might further hinder the distribution of the encapsulated drug, thereby limiting efficacy. It is necessary to release the drug from within the nanocarrier to promote increased efficacy. Here, we were able to address the problem of drug diffusion within the tumor interstitium using a combination therapy employing a remotely triggered thermosensitive liposomal chemotherapeutic. We fabricated a thermosensitive liposomal nanocarrier that maintained its stability at physiological temperature to minimize toxicity to healthy cells. We, then, showed a remote triggering mechanism mediated by gold nanorods heated via NIR can help in achieving precise control over the desired site for drug release. These strategies enabled increased drug availability at the tumor site and contributed to tumor retardation. Additionally, we show that the synergistic therapy employing gold nanorods and thermosensitive liposomes may have great potential to be translated to the clinic.

Pregnancy complications such as fetal growth restriction (FGR) are often attributed to poor uteroplacental blood flow, but the risk of systemic side-effects hinders therapeutic intervention. We have utilised novel placental-specific homing peptides to overcome this and have conjugated these to biocompatible liposomes. Peptide-conjugated liposomes were found to selectively bind to the outer syncytiotrophoblast layer of the human placenta and to the uteroplacental vasculature and labyrinth region of the mouse placenta. The novel vasodilator SE175 was selected as a nitric oxide donor with a favourable stability and release profile, to encapsulate in peptide-conjugated liposomes in an attempt to restore impaired uteroplacental blood flow in a mouse model of FGR, the endothelial nitric oxide synthase knockout mouse. Liposomes containing SE175 or PBS were prepared by lipid film hydration and targeting peptides coupled to the liposomal surface. Vehicle control, free SE175, PBS- or SE175-containing liposomes were intravenously injected on embryonic (E) days 11.5, 13.5, 15.5 and 17.5. Animals were sacrificed at E18.5 and fetal and placental weights recorded. Targeted delivery of SE175 significantly increased fetal weight compared to vehicle control but no other treatment groups, whilst significantly decreasing placental weight, indicating improved placental efficiency. Treatment was well tolerated, having no impact on litter size or resorptions. Targeted delivery of SE175, but no other treatment group, reduced a marker of lipid peroxidation in the placenta, indicating a reduction in oxidative stress. These data suggest that selective delivery of SE175 to the uteroplacental vasculature in peptide decorated liposomes may represent a novel treatment for FGR.

Le but de cette thèse de doctorat fut de développer des nanoparticules pour la délivrance de deux molécules hydrophobes de faible poids moléculaire, l’apigénine (AG) et un ferrocifène (FcTriOH), comme stratégie innovante pour le traitement du glioblastome(GBM). Dans un premier temps, différents types de nanoparticules, liposomes, nanocapsules lipidiques (LNC), et nanocapsules à base de polymères, furent formulés et comparés en termes de caractéristiques physico-chimiques, de libération en drogue ou encore de toxicité. Les LNCs furent ainsi sélectionnées. Dans un deuxième temps, les LNCs furent fonctionnalisées en surface par un peptide pénétrant (CPP). La concentration de peptide fut augmenté afin d’améliorer significativement l’internalisation des LNCsdans des cellules humaines de GBM. Les mécanismes de macropinocytose et d’endocytose dépendant de la clathrine et de la cavéoline furent observés. De plus, il fut montré que l’internalisation de ces LNCs fonctionnalisées était réduite dans les cellules saines humaines d’astrocyte. L’efficacité biologique des LNCs chargées en AG et chargées en FcTriOH fut évaluée et comparée : le résultat le plus prometteur fut obtenu avec les LNCs chargées en FcTriOH. Une administration intracérébrale des LNCs sur un modèle tumoral murin orthotopique montra une potentielle toxicité et un besoin d’optimiser la dose administrée. Pour finir, les études menées sur un modèle tumoral ectopique murin montrèrent des résultats prometteurs, après une administration parentérale des LNCs chargées en FcTriOH. Ainsi, cette dernière formulation pourrait ouvrir la voie au développement d’une stratégie thérapeutique alternative pour le traitement du GBM
The aim of this thesis was to develop nanocarriers for efficient delivery of two low molecular weight hydrophobic drugs, apigenin (AG) and a ferrocifen-derivative(FcTriOH) to glioblastoma (GBM) as potential therapeutic strategies. Firstly, two liposomes, a lipid nanocapsule (LNC), and a polymer-based nanocapsule were develope dand compared by their physicochemical characteristics, drug loading capacity, storage stability, stability in biological serum, drug release profiles, complement consumption and toxicity. Due to various advantageous characteristics, the LNCs were selected for further optimization. Secondly, the LNCs were surface functionalized by adsorbing a GBM-targeting cellpenetratingpeptide (CPP). The CPP concentration increased to significantly enhance LNCinternalization in human GBM cells. The uptake mechanisms observed in U87MG cellswere : micropinocytosis, clathrin-dependent and caveolin-dependent endocytosis. Moreover, the optimized CPP-functionalized LNCs were internalized preferentially in theGBM cells compared to normal human astrocytes. Additionally, the in vitro efficacy of the AG-loaded and FcTriOH-loaded LNCs was evaluated. The FcTriOH-loaded LNC-CPP showed the most promising activity with a low IC50 of 0.5 μM against U87MG cells. Intracerebral administration of the LNCs in a murine orthotopic U87MG tumor modelshowed possible toxic effects and the need for dose optimization. Finally, studies inmurine ectopic U87MG tumor model showed promising activity after parenteral administration of the FcTriOH-loaded LNCs. Overall, these results exhibit the promising activity of FcTriOH-loaded LNCs as potential alternative GBM therapy strategy

A fosfoetanolamina sintética (FO-S), um fosfomonoéster, apresenta relevante atividade antitumoral. Contudo, a utilização de um carreador para encapsular a FO-S em lipossomas poderia favorecer a sua disponibilidade no microambiente tumoral, possibilitando o aumento da sua eficácia. Desta forma, o presente estudo avaliou a eficiência de encapsulamento da FO-S em lipossomas de DODAC e o seu potencial antitumoral. Os lipossomas foram preparados por ultrasonicação e caracterizados físicoquimicamente. A citotoxidade foi avaliada nas linhagens tumorais B16F10 (melanoma murino), Hepa1c1c7 (hepatocarcinoma murino) e Skmel-28 (melanoma humano) e nas células normais HUVEC, após o tratamento com diferentes concentrações dos lipossomas DODAC/FO-S, no tempo de 24 horas. A internalização dos lipossomas e o potencial elétrico mitocondrial foram analisados por microscopia confocal a laser. Adicionalmente, a expressão das proteínas caspases 3 e 8 ativas, receptor DR4, citocromo c, p53, p21, Bax, p27, CD44, CD90, Bcl-2 e ciclina D1 foi quantificada por citometria de fluxo. Para os estudos in vivo, os camundongos C57BL/6J portadores de hepatocarcinoma foram tratados com FO-S, DODAC/FO-S e DODAC, pelas vias intraperitoneal (IP) e intrahepática (IH), durante 20 dias. Os resultados demonstraram que os lipossomas apresentaram aspecto esférico e alta eficiência de encapsulação da FO-S, como também promoveram maior citotoxicidade nas linhagens tumorais estudadas, em comparação com FO-S. Além disto, nas células B16F10 e Hepa1c1c7, ocasionou parada nas fases S e G2/M do ciclo celular. A linhagem Hepa1c1c7 foi a mais sensível ao tratamento com os lipossomas DODAC/FO-S, os quais foram internalizados em até 6 horas e promoveram a diminuição de CD90, CD44, ciclina D1 e Bcl-2, o aumento de p53, p21, p27, Bax e caspases 8 e 3 ativas e a liberação do citocromo c. O aumento significativo das caspases 8 e 3 ativas, expressão do receptor DR4 e a liberação do citocromo c também ocorreu nas linhagens B16F10 e Skmel-28. Os resultados in vivo mostraram que os lipossomas DODAC/FO-S e a FO-S não induziram hepatotoxicidade, nefrotoxicidade e caquexia. Os lipossomas DODAC/FO-S não ocasionaram mielossupressão e hemólise, apresentando menor toxicidade em relação a FO-S, administrada pelas vias IP e IH. Além disto, os tratamentos com DODAC/FO-S (IH) e FO-S (IH e IP) foram efetivos em diminuir o número de células na fase S. Contudo, apenas os lipossomas DODAC/FO-S (IH) reduziram significamente os focos tumorais, aumentando as áreas de necrose, promovendo também o aumento da expressão gênica da p53, ciclina B1 e caspases 8 e 3. O conjunto dos resultados in vivo e in vitro demonstraram que a formulação lipossomal DODAC/FO-S foi capaz de maximizar os efeitos antitumorais da FO-S, ativando as vias intrínsecas e extrínsecas da apoptose
Synthetic phosphoethanolamine (PHO-S) - a phosphomonoester - has shown relevant anticancer effects. However, the utilization of a carrier to encapsulate the PHOS in liposomes can maximize its availability in the tumor microenvironment, allowing an increase in its effectiveness. Thus, the present study has evaluated efficiency of PHO-S encapsulation in DODAC liposomes and its antitumor potential. The liposomes were prepared by ultrasonication and physico-chemically characterized. The cytotoxic effects were evaluated on B16F10 cells (murine melanoma), Hepa1c1c7 cells (murine hepatocellular carcinoma), Skmel-28 (human melanoma) and in endothelial cells HUVEC, after treatment with DODAC/PHO-S liposomes at different concentrations for 24 hours. The internalization of the liposomes and mitochondrial electrical potential were analyzed by confocal laser microscopy. Additionally, the expression of active caspases 3 and 8, receptor DR4, cytochrome c, p53 p53, p21, Bax, p27, CD44, CD90, Bcl-2 and cyclin D1 proteins was quantified by flow cytometry. For in vivo studies, C57BL/6J mice with hepatocellular carcinoma were treated with PHO-S, DODAC/PHO-S and DODAC, by intraperitoneal (IP) and intratumoral (IT) routes for 20 days. The results demonstrated that liposomes presented spherical aspect and high PHO-S encapsulation efficiency, as also promoted high cytotoxic effect - compared with PHO-S. Furthermore, in B16F10 and Hepa1c1c7 cells, the liposomes induced S and G2/M cell cycle arrest. Hepa1c1c7 cells showed greater sensitivity to the DODAC/PHO-S formulation, which were internalized until 6 hours and promoted a decrease in the expression of CD90, CD44, cyclin D1 and Bcl-2, an increase of de p53, p21, p27, Bax and active caspases 8 and 3 and the liberation of cytochrome c. The significant increase in the expression of active caspases 3 and 8, DR4 receptor and liberation of cytochrome c also occurred in B16F10 and Skmel-28 cells. In vivo results showed that DODAC/PHO-S liposomes and PHO-S did not induce nephrotoxicity, hepatotoxicity and cachexia. DODAC/PHO-S liposomes did not cause myelosuppression and hemolysis, presenting lower toxicity in relation to PHO-S - when administered by IP and IT routes. Moreover, treatment with DODAC/PHO-S (IT) and PHO-S (IT and IP) effectively decreased the number of cells in S phase. However, only DODAC/PHO-S liposomes significantly reduced the number of tumor foci, increasing area of necrosis, and also promoting an increase in gene expression of p53, cyclin B1 and caspases 8 and 3. The set of in vitro and in vivo results demonstrated that DODAC/PHO-S liposomal formulation was capable of maximizing the PHO-S antitumor effects, activating the intrinsic and extrinsic pathways of the apoptosis

Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-20T12:27:29Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DiegoBeckerBorin.pdf: 7060697 bytes, checksum: bbf39761011feb8708ec27ab4968daed (MD5)
Made available in DSpace on 2018-08-20T12:27:29Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DiegoBeckerBorin.pdf: 7060697 bytes, checksum: bbf39761011feb8708ec27ab4968daed (MD5) Previous issue date: 2017-03-27
The pathophysiology of neurodegenerative diseases is associated with neuronal loss or dysfunction, whose characteristics are determined due to cerebral area affected and progression of the disease. Creatine has physiological importance as energy buffer and storage having protective effects in animal models of neurodegenerative diseases. However, its permeability through the blood-brain barrier (BBB) is very low. The objective of this study is was developing a nanoliposome carrier to facilitate the delivery of creatine to the central nervous system (CNS), thus could potentiate the effects of creatine. In order to test the safety of liposomes toxicity, assays were performed in cell culture and in vivo, as well as analyzed in streptozotocin-induced (STZ) dementia model. The method of production of liposomes by ethanol injection, proved to be efficient, since particles with a polydispersion index (PDI) of 0,237, negative Zeta potential (-12.5 mV) and average size of 213 nm were obtained. The size was confirmed by transmission electron microscopy where spherical particles of 100-200 nm were observed. In in vitro toxicity assays, blank liposomes (without creatine - BL) as well as creatine liposomes (CrL) at concentrations of 0.02 and 0.2 mg/mL did not alter the viability of VERO cells cultured. It also did not alter viability of neural cells in hippocampal slices from adult rats. In toxicity assays in vivo, subchronic treatment with both liposomes did no changes hematological and biochemical markers in blood of young rats, but an increased in creatine concentrations were observed in the brains of CrL-treated animals was observed. In the animal model of STZ-induced dementia in adult mice, behavioral changes such as habituation memory deficit and long-term aversive memory were reversed by 21 days treatment with free creatine and CrL. The animals of the STZ groups did not present alterations in energetic metabolism enzymes in the hippocampus, but they showed a reduction in creatine levels in cerebral tissue, which was reversed by the treatment with free creatine and CrL. It is suggested from the results that CrL can be used safely, but further studies should be performed to verify its performance in other neurodegeneration models.
A fisiopatologia de doenças neurodegenerativas está associada à perda ou disfunção neuronal, cujas características são determinadas pela região onde ocorre a perda e pela velocidade de progressão da doença. A creatina possui importância fisiológica como mecanismo de reserva e tampão energético tendo efeitos protetores em modelos animais de doenças neurodegenerativas, apesar de possuir baixa permeabilidade através da barreira hematoencefálica (BHE). Assim, o objetivo do presente estudo foi desenvolver um carreador lipossomado para facilitar a entrega de creatina ao sistema nervoso central (SNC), e assim potencializar os efeitos da creatina livre. Com a finalidade de testar a segurança dos lipossomas testes de toxicidade em cultura de células e in vivo foram realizados, assim como testes em um modelo de demência induzido por estreptozotocina (STZ) para avaliar sua funcionalidade, também foi avaliada a concentração de creatina no SNC dos animais. O método de produção de lipossomas por meio da injeção de etanol demonstrou ser eficiente, pois foram obtidas partículas com índice de polidispersão (IPD) 0,237, potencial Zeta de -12,5 mV e tamanho médio de 213 nm. O tamanho foi confirmado por microscopia eletrônica de transmissão onde observou-se partículas esféricas de 100 a 200 nm. Nos testes de toxicidade in vitro, os lipossomas brancos (sem creatina - LB) bem como os lipossomas de creatina (LCr) nas concentrações de 0,02 e 0,2 mg/mL não alteraram a viabilidade de células em cultura da linhagem VERO, e tampouco de fatias da área cerebral hipocampo de ratos adultos. Nos testes de toxicidade in vivo, não foram observadas alterações com o tratamento subcrônico com ambos lipossomas em marcadores hematológicos e bioquímicos em ratos filhotes, porém foi observado um aumento nas concentrações de creatina no cérebro dos animais tratados com LCr. No modelo animal de demência induzido por STZ em camundongos adultos foram observadas alterações comportamentais como déficit de memória de habituação e aversiva de longo prazo ambas revertidas pelo tratamento de 21 dias com creatina livre e LCr. Os animais dos grupos STZ não apresentaram alterações em enzimas do metabolismo energético no hipocampo, porém apresentaram redução nos níveis de creatina, que foi revertido pelo tratamento com creatina livre e LCr. Sugere-se a partir dos resultados obtidos, que os LCr podem ser utilizados com segurança, porém mais estudos devem ser realizados para verificar seu desempenho em outros modelos de neurodegeneração.

Aquesta tesi aprofundeix en l’estudi de nanotransportadors com a sistemes de vehiculització i en alguns casos, alliberació de fotosensibilitzadors emprats en teràpia fotodinàmica. S’han fet servir dos nanotransportadors de naturalesa diferent: proteïnes i liposomes. En primer lloc s’ha investigat els complexos formats entre la hipericina i les proteïnes apomioglobina i β-lactoglobulina. S’han estudiat les característiques fisicoquímiques i fotofísiques, avaluant l’activitat antimicrobiana en front a bacteris gram-positius i gram-negatius. En ambdues matrius proteiques el fotosensibilitzador es troba majoritàriament en forma monomèrica, preservant les seves propietats fotofísiques i formant un complex estable. En el cas de la β-lactoglobulina s’estudia a més, la formació del complex amb l’adició d’un 20% de DMSO com a co-solvent, fet que millora les propietats fotofísiques en detriment de la capacitat antimicrobiana. Ambdós complexos proteics son efectius contra bacteris gram-positius però no contra gram-negatius. Per altra banda, es demostra que la hipericina incorporada a la cavitat de l’apomioglobina pot ser utilitzada en microscòpia de super-resolució STED. Amb aquesta tècnica es pot monitoritzar els llocs d’unió del fotosensibilitzador a la membrana dels bacteris. Així mateix, s’estudia l’ús de la β-lactoglobulina com a portador dual d’hipericina i àcid retinoic. En aquest últim sistema multi-component s’avaluen les propietats fotofísiques per a verificar la formació i estabilitat del complex. En segon lloc, es desenvolupa un nanovehicle per la seva aplicació en teràpia combinada en el qual s’incorporen fàrmacs quimioterapèutics convencionals amb agents fotosensibilitzants, per superar resistències i millorar l’eficàcia dels tractaments individuals. Amb aquest objectiu, s’han dissenyat i estudiat dues formulacions liposomals diferents, ambdues amb el mateix fotosensibilitzador però encapsulant diferents agents quimioterapèutics. Es preparen formulacions bimodals on s’incorporen els dos agents al mateix vehicle i els seus homòlegs unimodals, amb la incorporació única d’un dels dos agents. S’han avaluat les característiques fisicoquímiques, fotofísiques i fotobiològiques de les suspensions bimodals i unimodals. La lozalització subcel·lular demostra que cada principi actiu es localitza a orgànuls diferents desencadenant rutes de senyalització cel·lular diferents, eludint els possibles mecanismes de resistència. El tractament in vitro en cèl·lules cancerígenes amb aquests sistemes tenen un efecte prometedor, ja que com a mínim presenten un comportament additiu respecte els tractaments individuals. Finalment, s’ha avaluat el potencial de la vehiculització activa mitjançant la unió covalent d’un anticòs monoclonal a la superfície, el que millora lleugerament els resultats per una de les dues formulacions.
Esta tesis profundiza en el estudio de nanotransportadores como sistema de vehiculización y en algunos casos, liberación de fotosensibilizadores empleados en terapia fotodinámica. Se emplean dos nanotransportadores de naturaleza distinta: proteínas y liposomas. En primer lugar se han investigado los complejos formados entre hipericina y las proteínas apomioglobina y β-lactoglobulina. Se han estudiado las características fisicoquímicas y fotofísicas, evaluando la actividad antimicrobiana frente bacterias gram-positivas y gram-negativas. En ambas matrices proteicas el fotosensibilizador se encuentra mayoritariamente en forma monomérica, preservando sus propiedades fotofísicas y formando un complejo estable. En el caso de la β-lactoglobulina se estudia además, la formación del complejo con la adición del 20% de DMSO como co-solvente, lo que mejora las propiedades físicas pero sorprendentemente, empeora la capacidad antimicrobiana. Ambos complejos proteicos son efectivos contra bacterias gram-positivas, pero no contra gram-negativas. Además, se demuestra que la hipericina en la cavidad de la apomioglobina es capaz de realizar microscopía de super-resolución STED, mediante la cual se puede monitorizar los sitios de unión a las bacterias. Asimismo, se ha estudiado la β-lactoglobulina como portador dual de hipericina y ácido retinoico. En este último sistema multi-componente se evalúan las propiedades fotofísicas para verificar la formación y estabilidad del complejo. En segundo lugar, se desarrolla un nanovehículo para su uso en terapia combinada en el que se incorpora fármacos quimioterapéuticos convencionales con agentes fotosensibilizantes, para superar las resistencias y mejorar la eficacia de los tratamientos individuales. Con este objetivo, se han diseñado y estudiado dos formulaciones liposomales diferentes, ambas con el mismo fotosensibilizador, pero con diferentes agentes quimioterapéuticos. Se preparan las formulaciones bimodales con ambos agentes en el mismo vehículo además de sus homólogos unimodales, con la incorporación única de uno de los dos agentes. Se han evaluado las características fisicoquímicas, fotofísicas y fotobiológicas de las suspensiones bimodales y unimodales. La localización subcelular demuestra que cada principio activo se localiza en orgánulos diferentes desencadenando rutas de señalización celular diferentes, eludiendo los posibles mecanismos de resistencia. El tratamiento in vitro en células cancerígenas de estos sistemas tiene un efecto prometedor siendo al menos aditivo en comparación con los tratamientos individuales. Finalmente, se ha evaluado el potencial de la vehiculización activa mediante la unión covalente de un anticuerpo monoclonal en la superficie, lo que lleva a resultados ligeramente superiores para una de las dos formulaciones.
This thesis reports the study of nanocarriers as drug delivery systems for photosensitisers in photodynamic therapy. Proteins and liposomes are the two nanovehicles of different nature used for this purpose. Beginning with the proteins, the complexes formed between hypericin and the proteins apomyoglobin and β-lactoglobulin have been explored. The physicochemical and photophysical properties have been studied, as also assessing their photoantibacterial activity against Gram-positive and Gram-negative bacteria. In both protein scaffolds the photosensitiser is found mainly in monomeric form, preserving its fluorescence and singlet oxygen photosensitising properties and yielding a stable complex. In the case of β-lactoglobulin, the complex formation has also been tested with the addition of a 20% DMSO as a co-solvent, which improves the photophysical properties but surprisingly, worsens its antimicrobial activity. Both protein complexes are effective against Gram-positive but not against Gram-negative bacteria. Moreover, it has been proved that hypericin, inside the apomyoglobin cavity, can perform STED microscopy through which its localization in bacteria can be monitored. Additionally, the suitability of β-lactoglobulin as a dual carrier for hypericin and acid retinoic has also been exploited. In this last multi-component system, the photophysical properties have been evaluated to confirm the formation and complex stability. Secondly, a nanocarrier for its use in combined therapy has been developed, in which conventional chemotherapeutic drugs are combined with photosensitising agents to overcome resistance and improve the effectiveness of the individual treatments. For this purpose, two different liposome formulations have been designed and studied with a common photosensitiser but different anti tumour drugs. The bimodal formulations with both agents entrapped and their unimodal counterparts, having each drug loaded in separate liposomes, have been evaluated. The physicochemical, photophysical and photobiological properties of bimodal and unimodal suspensions have been studied. The subcellular localization shows different organelle accumulation by each agent, triggering different key signals transduction pathways, eluding the cellular resistance mechanisms. The treatment in vitro of these multi-component liposomes with cancer cells has a promising effect, since at least an additive outcome is observed when compared with the individual treatments. Finally, we have explored the potential of active targeting strategies by covalently linking a monoclonal antibody to the surface, leading to slightly greater outcomes for one of the liposomal formulations.

Nanocarriers have been established as delivery vehicles to target cancer tumors. However, premature drug leakage is one of the major reasons for inefficient drug delivery of nanocarriers to the tumor. Drug diffusion out of the nanocarriers or destabilization of drug loaded nanocarriers by physiological interactions with blood cells, serum proteins, and cell membranes upon systemic administration contribute to premature drug release. In this study, targeted micelles, liposomes and solid lipid nanoparticles (SLNs) of similar composition were prepared and characterized to compare physicochemical characteristics, in vitro stability, in vitro release rates in release media and in vivo performance. Peptide Amphiphiles (PAs) formed micelles with critical micelle concentration (CMC) values ranging between 23.68 ± 0.72 µM to 38.76 ± 2.27 µM. Transmission Electron Microscopy (TEM) images confirmed the self-assembly of PAs into spherical structures where the largest sizes were seen for C16-(PEG2)6-LDV micelles. Dynamic Light Scattering (DLS) results confirmed the presence of targeted liposomes and SLNs with sizes smaller than 100 nm. Forster Resonance Energy Transfer (FRET) studies revealed that targeted micelles, liposomes and SLNs were all stable upon dilution in aqueous medium, however the stability was significantly reduced in human serum, with micelles being the least stable and SLNs being the most stable. The same trend was observed for the in vitro release profiles, where targeted paclitaxel-loaded micelles (PTX-micelles) had the fastest release rate and paclitaxel-loaded SLNs (PTX-SLN) exhibited the slowest release rate. DLS results showed that sizes of PTX-SLNs were smaller than PTX-liposomes (80.53 ± 5.37 nm vs 123.31 ± 5.87 nm). Cryogenic TEM observation showed increasing size in the order of PTX-micelles (6 to 12 nm) < PTX-SLNs (10-120 nm) < PTX-liposomes (48-145 nm). Drug Loading Content (DLC) of PTX-SLNs was greater than PTX-micelles and PTX-liposomes (7.45 ± 0.41 % vs 1.70 ± 0.42 % and 0.92 ± 0.09 %). Compared to initial aqueous dispersions, reconstituted spray dried formulations maintained their nanosize and paclitaxel content over 7 days at 4⁰C. In A375 melanoma xenograft mouse model, the tumor volumes were significantly smaller for mice treated with PTX-SLNs compared to the control group. Furthermore, tumor volumes were significantly smaller for mice treated with PTX-SLNs compared to those treated with PTX-micelles and PTX-liposomes. These studies demonstrate the potential of stable PTX-SLNs for targeted delivery in cancer.

Les dificultats existents en l’administració de certs fàrmacs, que es tradueix en una considerable reducció de la seva eficàcia terapèutica, ha portat a l’exploració d’un nou camp en la recerca de fàrmacs, l’ús de polímers per a transportar fàrmacs. Aquests polímers es presenten com a vehicles transportadors que aporten protecció al fàrmac, evitant la seva degradació, i permeten la seva distribució dirigida fins la diana terapèutica, disminuint així els efectes secundaris. Una combinació adequada del polímer transportador amb el fàrmac, permet l’alliberament d’aquest en el teixit on ha de desenvolupar el seu efecte terapèutic. Tot i així, per tal de garantir l’èxit d’aquests sistemes de distribució de fàrmacs, aquests han de complir una sèrie de requisits pel que fa a la mida, càrrega superficial, composició, capacitat d’encapsular i d’alliberar un fàrmac, funcionalització i biocompatibilitat. En aquest treball, s’ha explorat la fabricació de diversos sistemes de distribució de fàrmacs per tal d’aportar coneixement sobre la modificació d’aquests polímers, que permetin obtenir plataformes de distribució de fàrmacs que reuneixi els requisits prèviament esmentats. Per una banda, s’ha obtingut un sistema termosensible i versàtil a través d’una estratègia de core-shell, que permet ajustar la seva mida i el seu comportament termosensible, com també la seva modificació superficial mitjançant un mètode fàcil i ràpid basat en una química clàssica. Per altra banda, la preparació de sistemes polimersòmics s’ha explorat per polimerització de tipus RAFT, és a dir, s’empra una química més sofisticada, que permet la síntesi de copolímers de multibloc amfifílics i auto-ensamblables, des de dos fins a cinc blocs, de manera controlada, obtenint polímers de pes molecular determinada amb distribucions de pes molecular molt estretes. De manera similar a l’anterior sistema, la modulació de la proporció entre blocs i del nombre de blocs permet el control de la mida de les nanoestructures formades i de la seva capacitat d’encapsular fàrmacs. Finalment, els sistemes polimersòmics desenvolupats s’han comparat amb un sistema de distribució de fàrmacs molt ben establert, com ara els liposomes, pel que fa a funcionalització, encapsulació i alliberament de fàrmacs, com a potencials sistemes de distribució de fàrmacs per al tractament de metàstasis de càncer de mama al cervell a través d’una estratègia de doble funcionalització, per tal d’avaluar la idoneïtat del sistema desenvolupat en aquest treball.
Las dificultades existentes en la administración de ciertos fármacos, que se traduce en una considerable reducción de su eficacia terapéutica, ha llevado a la exploración de un nuevo campo en el desarrollo de fármacos, el uso de polímeros como transportadores de estos. Estos polímeros se presentan como vehículos transportadores que aportan protección al fármaco, evitando así su degradación i permitiendo su distribución dirigida hasta la diana terapéutica, disminuyendo a su vez los efectos secundarios. Una combinación adecuada del polímero transportador con el fármaco, permite la liberación de este en el tejido dónde debe desarrollar su efecto terapéutico. Aun así, con tal de garantizar el éxito de estos sistemas de distribución de fármacos, estos deben cumplir una serie de requisitos por lo que respecta a tamaño, carga superficial, composición, capacidad de encapsular i liberar un fármaco, funcionalización i biocompatibilidad. En este trabajo, se ha explorado la fabricación de varios sistemas de distribución de fármacos con la finalidad de aportar conocimiento sobre la modificación de estos polímeros, que permitan obtener plataformas de distribución de fármacos que reúnan los requisitos previamente mencionados. Por un lado, se ha obtenido un sistema termosensible i versátil a través de una estrategia de core-shell, que permite ajustar su tamaño i su comportamiento termosensible, como también su modificación superficial mediante un método fácil i rápido basado en química clásica. Por otro lado, la preparación de sistemas polimersómicos se ha explorado mediante polimerización RAFT, es decir, utilizando una química más sofisticada, que permite la síntesis de copolímeros de multibloque amfifílicos i auto-ensamblables, desde dos a cinco bloques, de manera controlada, obteniendo polímeros de peso molecular determinado con distribución de peso molecular muy estrecha. De manera similar al anterior sistema, la modulación de la proporción entre bloques i del número de bloques permite el control del tamaño de las nanoestructuras formadas i de su capacidad de encapsular fármacos. Finalmente, los sistemas polimersómicos desarrollados se han comparado con un sistema de distribución de fármacos muy bien establecido, como son los liposomas, por lo que respecta a su funcionalización, encapsulación i liberación de fármacos, como potenciales sistemas de distribución de fármacos para el tratamiento de metástasis de cáncer de mama al cerebro a través de una estrategia de doble funcionalización, con tal de evaluar la idoneidad del sistema desarrollado en este trabajo.
The existing difficulties in the delivery of certain drugs, having a direct influence on their therapeutic efficiency, has lead to the exploration of a new field in pharmaceuticals, the use of polymers as drug carriers. Polymers are presented as carrier vehicles, which provide drug protection preventing its degradation and targeted delivery to the site of action diminishing side effects. An appropriate combination of the drug and the polymer allows the release of the drug in the tissue where it has to develop its therapeutic effect. However, in order to ensure the success of these drug delivery systems, they must fulfil a list of requirements according to size, surface charge, composition, drug loading capacity and release, targetability and biocompatibility. In this work, the fabrication of diverse drug delivery systems has been explored in order to provide know-how regarding polymers’ tunability to achieve delivery platforms that fulfil the aforementioned requirements. On one hand, a versatile thermo-responsive delivery system has been obtained trough a core-shell approach, allowing the tailoring of its size and thermosensitivity, while providing a simple and fast method to decorate its surface by means of classic chemistry. On the other hand, the preparation of polymersomic systems was explored by RAFT polymerization, a more sophisticated chemistry, which allowed the synthesis of self-assembling amphiphilic multiblock copolymers, ranging from diblock to pentablock, in a controlled manner, obtaining predetermined molecular weight polymers with narrow molecular weight distributions. Similarly to the previous system, the tunability of blocks ratio and number allowed the control over nanostructures size and loading capacity. Finally, polymersomes have been compared with a very well established delivery system, such as liposomes, in terms of targeting and drug loading and release, as potential drug delivery systems to breast cancer metastasis in the brain through a dual-targeting approach, in order to evaluate the suitability of the system developed in this work.

Brain and central nervous cancer presents a significant clinical burden, accounting for 2.4% of all cancer deaths. High grade glioma is particularly deadly, with 5 year survival times of 35% or less. Traditional treatment includes tumor resection followed by radiation therapy or chemotherapy. Aggressive resection is essential in order to prolong patient life. In fact, several studies have shown that life expectancy increases with increased extent of resection. Extent of resection is burdened by the fact that surgeons must be careful not to remove functional brain tissue. Resection is incomplete more often than not due to lack of visual cues for the surgeon. He must rely on tactile sensation to distinguish tumor from healthy tissue. Methods such as intraoperative MRI and CT exist, but these require expensive equipment and special training that is not available in all surgical environments. Some laboratories have proposed small molecule dyes to solve this problem, but these are insufficient when used in an invasive tumor model. It was the goal of this research to provide an objective cue in the form of a nanoencapsulated visible dye without the need for additional equipment of changes to the surgery process itself other than injection of the dye. We hypothesized that the nanocarrier would allow staining of the tumor through passive targeting by taking advantage of the enhanced permeability and retention effect. Once the nanocarriers have reached the desired target, they would not diffuse out into healthy tissue due to their large size compared to small molecule dyes, which readily diffuse out and stain healthy tissue. To test this hypothesis, we prepared and characterized a liposomal nanocarrier encapsulating Evans blue dye. The nanocarrier was tested for safety in vitro and in vivo, then used to delineate tumor margins in an invasive rat glioma model in vivo. Microscopic analysis was then conducted to ensure only tumor tissue was stained by the nanocarrier. This thesis presents a successful method of tumor border delineation to provide surgeons with positive visual cues without the need for changes in surgical environment or techniques.

L'objectif de ce travail de thèse a été d'élaborer et de caractériser des systèmes de nanovecteurs de nature lipidique, encapsulant le dipropionate de beclomethasone (DPB), adaptés à l'administration pulmonaire par nébulisation. Deux types de nanovecteurs lipidiques : des liposomes et des nanoparticules lipidiques incluant les nanoparticules solides (SLN) et les nanoporteurs lipidiques (NLC), ont été développés. Les liposomes ont été préparés par la technique d'injection d'éthanol. La technique appliquée pour la préparation des nanoparticules lipidiques était l'homogénéisation à haute vitesse. La taille, l'efficacité d'encapsulation du DPB ainsi que les profils de libération ont été satisfaisants. De plus la nébulisation de ces systèmes et la modélisation mathématiques de la déposition in vitro ont révélé des résultats prometteurs. Finalement, une technique de production des liposomes utilisant un réacteur membranaire a été étudiée pour une production à grande échelle
The objective of this work was to prepare and to characterize lipidic nanocarriers systems encapsulating the beclomethasone dipropionate (BDP) and adapted to the nebulized pulmonary drug delivery. Two types of lipidic carriers: the liposomes and the lipidic nanoparticles including the solid lipid nanoparticles (SLN) and the nanostructured lipid carriers (NLC) were developed. Liposomes were prepared by the optimised ethanol injection based technology. The lipid nanoparticles were prepared by using the high shear homogenization process. Small sized particles, with high BDP encapsulation efficiency as well as a prolonged release effect in vitro were successfully obtained. Furthermore, the nebulized suspensions characteristics and deposition mathematical simulation in vitro revealed promising results. Finally, a liposomes production technique using a membrane contactor was investigated in order to produce large batches

The use of nanocarriers is an intriguing approach in the development of efficacious treatment for brain disorders. The aim of the conducted research was to evaluate and quantify the impact of a liposomal nanocarrier formulation on the brain drug delivery. A novel approach for investigating the blood-brain barrier transport of liposomal DAMGO is presented, including in vivo microdialysis in rat, a high quality LC-MS/MS bioanalytical method and pharmacokinetic model analysis of the data. Factors limiting the brain distribution of the free peptide DAMGO were also investigated. Microdialysis, in combination with plasma sampling, made it possible to separate the released drug from the encapsulated and to quantify the active substance in both blood and brain interstitial fluid over time. The opioid peptide DAMGO entered the brain to a limited extent, with a clearance out of the brain 13 times higher than the clearance into the brain. The brain to blood ratio of unbound drug was not affected when the efflux transporter inhibitors cyclosporine A and elacridar were co-administered with DAMGO. Nor was the transport affected in the in vitro Caco-2 assay using the same inhibitors. This indicates that DAMGO is not transported by P-glycoprotein (Pgp) or breast cancer resistant protein (Bcrp). The blood-brain barrier transport was significantly increased for DAMGO when formulated in liposomes, resulting in 2-3 fold higher brain to blood ratio of unbound DAMGO. The increased brain delivery was seen both for glutathione tagged PEGylated liposomes, as well as for PEGyalted liposomes without specific brain targeting. The improvement in brain delivery was observed only when DAMGO was encapsulated into the liposomes, thus excluding any effect of the liposomes themselves on the integrity of the blood-brain barrier. Modeling of the data provided additional mechanistic understanding of the brain uptake, showing that endocytosis or transcytosis of intact liposomes across the endothelial cell membranes were unlikely. A model describing fusion of the liposomes with the luminal membrane described the experimental data the best. In conclusion, the studies presented in this thesis all contribute to an increased understanding of how to evaluate and improve brain delivery of CNS active drugs and contribute with important insights to the nanocarrier field.

Drug Delivery Systems represent a useful strategy to improve water solubility, improper dissolution rate, permeation or absorption, bioavailability, little pharmacokinetics and physical-chemical stability of natural substances as essential oils (EOs), peptides and khellin. In the last years a remarkable number of publications on the antimicrobial and antifungal activity of EOs appeared in the literature, strongly motivated from the growing resistance. Khellin, instead, is a natural furanochromone, extracted from the plant Amni visnaga, having anti-vitiligo, antiinflammatory and analgesic activities. Considering this context, the aim of my PhD project was the design, optimization, characterisation and study of performance of nanocarriers loaded with the over cited compounds for topical, transdermal and oral delivery. All nanocarriers were physically and morphological characterized, their stability over time were evaluated as their ability to encapsulate and release the active principles. The EOs of Salvia triloba, Rosmarinus officinalis and Artemisia annua were chemically characterized, encapsulated in appropriate liposomal formulation and tested for their antioxidant, anti-inflammatory, antifungal or antibacterial activities. Khellin were loaded in ascosomes, vesicles prepared with Ottanoyl or Decanoyl-6-O-Ascorbic Acid Esters, in order to obtain nanocarriers value for topical and transdermal activity with added antioxidant. The structural and physical characteristics of the resulting colloidal dispersion were compared to conventional liposomes and further investigated by SAXS and DSC as their permeation and antioxidant capacities. Finally, were developed and optimised semisolid formulations of khellin vesicles which were tested also for the potential liver toxicity of khellin on rats. Moreover, khellin was loaded in a Nanostructured lipid carrier specifically ideated for oral administration. After the conventional characterization and the stability test in gastrointestinal medium, the system were evaluated for its permeation capacity through PAMPA assay and Caco-2 cells. To conclude, a synthetic conjugated peptide (PalmSA1-III), have been loaded in vesicular systems in order to enhance its permeation in the skin and test its activity in fibroblasts for its protective effect against collagen degradation. The findings on all the over cited drug delivery systems suggest that these formulations can decrease the natural substances limits and optimize their biological properties proving to be useful in clinical practice after further investigations. I DDS rappresentano una strategia utile per migliorare la solubilità in acqua, la dissoluzione, la permeazione o l'assorbimento, la biodisponibilità, la scarsa farmacocinetica e la stabilità fisico-chimica delle sostanze naturali come oli essenziali (EO), peptidi e kellina. Negli ultimi anni sono state pubblicate numerose pubblicazioni sull'attività antimicrobica e antimicotica degli OE, fortemente motivate dalla crescente resistenza dei microrganismi ai farmaci convenzionali. La kellina, invece, è un furanochromone naturale, estratto dalla pianta Ammi visnaga, con attività anti-vitiligine, antiinfiammatoria e analgesica. Considerando questo contesto, l'obiettivo del mio progetto di dottorato è stato la progettazione, l'ottimizzazione, la caratterizzazione e lo studio dei nanocarrier caricati con i composti sopra citati per uso topico, transdermico o orale. Tutti i nanocarrier sono stati caratterizzati fisicamente e morfologicamente, e sono state valutate la loro stabilità nel tempo e la loro capacità di incapsulare e rilasciare i principi attivi. Gli EO di Salvia triloba, Rosmarinus officinalis e Artemisia annua sono stati caratterizzati chimicamente, incapsulati in un'adeguata formulazione liposomiale e testati per le loro attività antiossidanti, antinfiammatorie, antimicotiche o antibatteriche. La kellina è stata caricata in ascosomi, vescicole preparate con ascorbil ottanoato o decnoato, al fine di ottenere un ottimo nanocarrier per uso topico e transdermico con capacità antiossidante ed ad alta permeazione. Le caratteristiche strutturali e fisiche della risultante dispersione colloidale sono state confrontate con i liposomi convenzionali e ulteriormente studiate con SAXS e DSC. Infine, sono state sviluppate e ottimizzate formulazioni semisolide con gli ascosomi di kellina, testate anche per la potenziale tossicità epatica sui ratti. Inoltre, la kellina è anche stata caricata in un veicolo lipidico nanostrutturato (NLC) appositamente ideato per la somministrazione orale. Dopo la caratterizzazione convenzionale ed il test di stabilità nel mezzo gastrointestinale, tale sistema è stato valutato per la sua capacità di permeazione attraverso il dosaggio PAMPA e le cellule Caco-2. Per concludere, un peptide coniugato sintetico (PalmSA1-III) è stato caricato nei sistemi vescicolari al fine di migliorare la sua permeazione nella pelle e testare la sua attività nei fibroblasti per il suo effetto protettivo contro la degradazione del collagene. I risultati su tutti i sistemi di consegna dei farmaci sopra citati suggeriscono che queste formulazioni possono ridurre i limiti delle sostanze naturali e ottimizzare le loro proprietà biologiche dimostrando di poter essere utili anche nella pratica clinica.

Nanoscale drug delivery systems have a great impact in current medical field. These carriers have the potential to improve the efficacy and reduce the toxicity of various medicinal products. A broad variety of different lipid based carriers had been developed and used as delivery systems in the past decades. This dissertation focused on the development of solid lipid nanoparticles (SLN) as delivery systems for a chemotherapeutic agent, docetaxel, and the use of liposomes as a carrier for recombinant protein vaccines. Docetaxel is a potent anticancer drug. However, there continues to be a need for alternative docetaxel delivery systems to improve its efficacy. Docetaxel nanoparticles comprised of lecithin as the main component were engineered using two methods, the emulsion precursor method and the solvent emulsification/evaporation method. Docetaxel in nanoparticles were more effective in killing tumor cells in culture than docetaxel solution. The intravenously injected docetaxel-nanoparticles increased the accumulation of docetaxel in tumors in mice. When administered by intravenous injection or oral routes, docetaxel-nanoparticles showed antitumor activity in tumor-bearing mice. The lecithin-based nanoparticles have the potential to be a novel biocompatible and efficacious delivery system for docetaxel. Liposomes, a well-known lipid based carrier, have been investigated extensively as a vaccine delivery system. The adjuvant activities of liposomes with different net surface charges (neutral, positive, or negative) were evaluated when simply admixed with protein antigens. Immunization study in mice after subcutaneously injection of different net charged liposomes showed different antibody responses, depending on the protein antigens. Antigens (OVA, PA) admixed with the negatively charged liposomes prepared with phospholipid, DOPA, induced a strong and functional antibody response comparable to the positively charged liposomes prepared with DOTAP lipid. The negatively charged DOPA liposomes admixed with OVA also induced OVA-specific CD8��� cytotoxic T lymphocyte responses and significantly delayed the growth of OVA-expressing B16-OVA melanoma in a mouse model. The adjuvant activity of the negatively charged liposomes may be related to the liposome's ability (i) to upregulate the expression of molecules related to the activation and maturation of antigen-presenting cells and (ii) to slightly facilitate the uptake of the antigens by antigen-presenting cells. Simply admixing certain negatively charged liposomes with certain protein antigens of interest may represent a novel platform for vaccine development.
Graduation date: 2012
Access restricted to the OSU Community at author's request from Sept. 6, 2011 - Sept. 6, 2012