Multisensitive polyurethane/polyurea nanocapsules for smart drug delivery
The Thesis is based on the development of a potentially-scalable methodology to prepare polyurethane/polyurea polymers to nanoencapsulate bioactive molecules. In the first part of the project, the design, optimization and characterization of the polymers were presented, and it showed that the most p...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/543852 |
| Acceso en línea: | http://hdl.handle.net/10803/543852 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciències de la salut Ciencias biomédicas Medical sciences Nanopartícules Nanopartículas Nanoparticles Polímers en medicina Polímeros en medicina Polymers in medicine Ciències Experimentals i Matemàtiques 547 |
| Sumario: | The Thesis is based on the development of a potentially-scalable methodology to prepare polyurethane/polyurea polymers to nanoencapsulate bioactive molecules. In the first part of the project, the design, optimization and characterization of the polymers were presented, and it showed that the most promising polymer was composed of hydrophilic and hydrophobic pendant tails, disulfide bonds and an amphoteric pair. The polymers synthesized were basically characterized by IR, NMR, MALDI-TOF, which indicated that the polyaddition reactions between the isocyanates and the difunctional nucleophiles proceeded as expected and the polymer grew to the desired molecular weight. The most promising polymer was used to nanoencapsulate four hydrophobic drugs in a straightforward manner. The nanocapsules were subsequently characterized by different biophysical techniques and showed that the nanosystems were monodisperse and that the average particle size was around 20 nm. In addition, surface charge measurements demonstrated a synchronized shell cationization under acidic conditions, while the nanosystem remained neutral to anionic under physiological pH. Fluorescence and morphological studies revealed that the nanocapsules were stable under physiological conditions and in protein-rich environments, while they degraded under a glutathione- based medium. Finally, UV/Vis spectroscopy demonstrated that the encapsulation efficiency was high for the four cases studied. The second part of the thesis aimed the extension of this methodology to amphiphilic molecules, such as anionophores (tambjamines). The application of the process without modifications led to nanosystems with highly cationic surfaces and low entrapment efficiencies, therefore, different changes were proposed. Firstly, certain modifications of the shell were considered, such as the use of aliphatic isocyanates with aromatic moieties, but they did not lead no any improvement. Secondly, the insertion of hydrophobizing agents was also tested and the results revealed a more homogeneous particle size distribution, a pH-responsive surface and a medium to high entrapment efficiency. The most promising nanocapsules were characterized in vitro in terms of cytotoxicity, cell uptake and cell internalization. The first parameter was evaluated in three different lung cancer cell lines, a normal cell line (fibroblasts) and two different neuroblastoma cell lines. The assays showed that unloaded nanocapsules did not induce any cytotoxicity in any of the cell lines tested, and the nanocapsules loaded with the drug led to a controlled cytotoxic effect that was maximum after 72 h of incubation. Moreover, the nanocapsules internalized the lung cancer cells by endosomal mechanisms and they were transported as late endosomes to the lysosomes, where they are hydrolyzed. The last in vitro assays demonstrated that the nanocapsules were uptaken after only 1 h of treatment and after 48 h the cells did not show signs of saturation. Finally, in vivo biodistribution studies were performed with amphoteric nanocapsules and antiGD2- functionalized nanocapsules in a neuroblastoma mice model. The ex-vivo results revealed that the amphoteric nanocapsules promoted an improved tumor accumulation compared to the antibody-targeted nanosystems. However, both types of nanocapsules were highly accumulated to detoxification organs, such as the liver and spleen. These undesired effects could be explained by the fact that an excessive dose of product was administered taking into account the small size and low weight of the tumors. Finally, the last part of the project involved the functionalization of the nanocapsules with peptides (A5 and IPEP) to target different types of breast cancer cells. To this aim, different hydrophilic linkers were synthesized to conjugate the peptides and provide a physical space between them and the nanocapsules. The nanosystems were prepared and evaluated by the typical techniques and by flow cytometry in order to determine the effect of targeting molecules on the surface. The results showed that only IPEP provided an improved cell penetration, since A5 did not induce any significant effect. This could be explained by the fact that A5 had lost its biological activity after being functionalized, since different data supported the presence of these peptides on the surface. |
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