|Tipo di tesi||Tesi di dottorato di ricerca|
|Autore||DE VITA, ALESSANDRO|
|Titolo||Nanoparticelle polimeriche allestite in emulsione semplice: preparazione, ottimizzazione dei parametri formulativi ed applicazione nella terapia antitumorale|
|Titolo in inglese||Polymeric Nanoparticles by single emulsion: preparation, optimization of formulative parameters and tumor therapy application|
|Settore scientifico disciplinare||CHIM/09 - FARMACEUTICO TECNOLOGICO APPLICATIVO|
|Corso di studi||Scuola di D.R. in SCIENZE E TECNOLOGIE DEI PRODOTTI PER LA SALUTE|
|Data inizio appello||2013-02-13|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
Le nanoparticelle polimeriche (Nps) sono tra i vettori maggiormente indagati e proposti per la veicolazione ed il direzionamento dei farmaci. Le Nps sono sistemi colloidali costituiti da polimeri naturali o sintetici aventi dimensioni comprese tra 50 e 500 nm. L’interesse per questi nanocarriers trova il razionale nella versatilità formulativa e nella possibilità di modificazione superficiale attuata per modulare i parametri farmacocinetici.
Over the past few decades, great interest was dedicated to develope biodegradable polymeric nanoparticles (Nps) as effective drug delivery devices. Nps are spherical colloidal systems consisting of natural or synthetic polymers sizing 50 and 500 nm. The interest for Nps finds its rational in the versatility of the formulation, as well as in the possibility of surface engineering, thus enabling to modulate pharmacokinetic parameters. In the first part of the PhD project, PLGA Nps able to cross the Brain-Blood Barrier by a conjugation with a selective glyco-heptapeptide were formulated; Nps were also modified with a fluorescence probe in order to validate their use in diagnostic field. Results suggested the brain localization of Nps, confirming the possibility to use these Nps as a promising tool for the imaging of brain through the optical imaging. Subsequently, Nps skilled both in the stabilization and the targeting of the anticancer drugs were investigated. The technological study was oriented to the optimization of the formulative parameters aiming to produce Nps with single emulsion technique, relatively poorly investigated, but it has been demonstrated to be useful for the encapsulation of hydrophobic drugs featured by chemical-physical characteristics inadequate for the administration. Different parameters of the formulation process were investigated, such as the output and times of sonication, procedures and characteristics of purification, conservation and lyophilization conditions with the use of different cryoprotector concentrations. Stable and homogeneous nanoemulsions were formed with low output and time of sonication. Consequently, monomodal and monodisperse Nps were obtained, featured by 200 nm size. The centrifugation at 15000 rpm for 10 min lead to pellettization and purification of Nps, the use of trehalose in minimal amounts allowed to the resuspension after lyophilization. These formulative conditions were used to prepare Nps loaded with an anticancer drug, Nutilin-3a. Nutlin-3a is a small molecule MDM2 antagonist. MDM2 binds p53 (a tumor suppressor) inducing its proteasomal degradation and making the cell unable to activate apoptotic pathways. Several recent studies have strengthened the notion that the selective non-genotoxic activation of p53 by Nutlin-3a could represent an alternative to on going chemotherapy. Unfortunately, Nutlin-3a shows several limitations such as the poor solubility in aqueous medium and the consequent limited bioavailability. The formulation of Nutlin-3a loaded Nps led to the stabilization of quantities of drug sufficient to undertake in vitro and in vivo studies and evaluating a possible drug administration. Nps have been subsequently modified on their surface with a monoclonal antibody (Rituximab) and directed against tumor cells to finally obtain a selective targeting. Rituximab was conjugated to the surface of Nps adapting and optimizing well-known techniques of Nps surface engineering. In addition to the physical-chemical characterization of these systems, the surface derivatization was evaluated both qualitatively (using atomic force microscopy) and quantitatively (by spectroscopic techniques); the 7% of Nps surface is conjugated to the antibody. This amount could be theoretically considered as a sufficient quantity, to promote a selective targeting to the target cell. In vitro and in vivo studies are running to demonstrate the targeting and the delivery effectiveness.