This thesis is focused on the synthesis of biodegradable cationic polymers and novel contrast agents for biomedical applications, in particular gene delivery and 19F-MRI. The development of polymeric non-viral vectors for gene delivery has gained great attention in the last years, due to their potentiality to overcome the cytotoxicity and the non-biodegradable nature of the golden standard nowadays present in literature. However, transfection efficiency remains the principle obstacle of these kind of systems. In the first part of this study, ionizable amino-polyesters were synthesized varying the length of lipophilic component, via ring opening polymerization and free radical polymerization in order to produce a library of positively charged polymers. Using a zwitterionic-based polymer, stable nanoparticles were developed. Depth study over the size of the different NPs obtained were done and a preliminary transfection test in vitro was performed using the polyplex that has shown the most suitable characteristics. Furthermore, degradation test was done to demonstrate the degradability of NPs both in physiological pH and extreme basicity conditions. In the second part, novel polymeric nano-contrast agents detectable via 19F-MRI were synthesized. In fact, the use of fluorine 19F has been considered a novel strategy to enhance quantitative MRI. Via click-chemistry a reactive perfluorated PERFECTA-based molecule was obtained and used for subsequent reactions, for both gene delivery and imaging purpose, to synthesize functionalized poly (beta-amino esters) through Michael type addition, and nanotracer via polymerization induced self-assembly (PISA). The obtained compounds were characterized via nuclear resonance and nano-size analysis.
Il seguente lavoro di tesi si concentra sulla sintesi di polimeri cationici biodegradabili per applicazioni biomedicali, quali gene delivery e 19F-MRI. Lo sviluppo di vettori non virali a base polimerica ha incrementato un grande interesse negli ultimi anni, a causa della loro possibile capacità di superare i problemi di citotossicità e non biodegradabilità emersa con i vettori non-virali comunemente usati nella ricerca scientifica. Tuttavia, l’efficienza di trasfezione resta l’ostacolo principale per questa tipologia di sistemi. Nella prima parte del lavoro, sono stati sviluppati poli-aminoesteri ionizzabili, variando la lunghezza della componente lipofila, mediante polimerizzazione ad apertura di anello e polimerizzazione radicalica libera, per produrre una libreria di polimeri cationici. Utilizzando un polimero zwitterionico è stato possibile sintetizzare nanoparticelle stabili in ambiente acquoso. Uno studio approfondito sulla dimensione delle nanoparticelle è stato sviluppato e un test preliminare di trasfezione in vitro è stato performato considerando la nanoparticella con le migliori caratteristiche. In più, per dimostrare il comportamento degradabile della NP, è stata studiata la cinetica di degradazione sia in condizioni di pH fisiologico che in condizioni di elevata basicità. Nella seconda parte del lavoro, sono stati sintetizzati agenti di contrasto di dimensioni nanometriche e di natura polimerica rilevabili mediante risonanza magnetica a 19F. L’utilizzo degli isotopi del fluoro è considerato una strategia innovativa per incrementare il segnale di MRI. Mediante click-chemistry, una molecola fluorata derivante dal PERFECTA è stata ottenuta ed utilizzata nelle successive reazioni di sintesi per sviluppare un poli-beta aminoestere fluorato mediante reazione di addizione di Michael, e un nanotracer via polimerizzazione indotta da self-assembly (PISA), per applicazioni sia di gene delivery che di imaging. I composti ottenuti sono stati caratterizzati mediante spettroscopia nucleare e sistemi di analisi della dimensione alla nano-scala.
Synthesis of biodegradable cationic polymers for gene delivery and smart imaging applications
ROMANI, CAROLA
2018/2019
Abstract
This thesis is focused on the synthesis of biodegradable cationic polymers and novel contrast agents for biomedical applications, in particular gene delivery and 19F-MRI. The development of polymeric non-viral vectors for gene delivery has gained great attention in the last years, due to their potentiality to overcome the cytotoxicity and the non-biodegradable nature of the golden standard nowadays present in literature. However, transfection efficiency remains the principle obstacle of these kind of systems. In the first part of this study, ionizable amino-polyesters were synthesized varying the length of lipophilic component, via ring opening polymerization and free radical polymerization in order to produce a library of positively charged polymers. Using a zwitterionic-based polymer, stable nanoparticles were developed. Depth study over the size of the different NPs obtained were done and a preliminary transfection test in vitro was performed using the polyplex that has shown the most suitable characteristics. Furthermore, degradation test was done to demonstrate the degradability of NPs both in physiological pH and extreme basicity conditions. In the second part, novel polymeric nano-contrast agents detectable via 19F-MRI were synthesized. In fact, the use of fluorine 19F has been considered a novel strategy to enhance quantitative MRI. Via click-chemistry a reactive perfluorated PERFECTA-based molecule was obtained and used for subsequent reactions, for both gene delivery and imaging purpose, to synthesize functionalized poly (beta-amino esters) through Michael type addition, and nanotracer via polymerization induced self-assembly (PISA). The obtained compounds were characterized via nuclear resonance and nano-size analysis.| File | Dimensione | Formato | |
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2019_12_Romani.pdf
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https://hdl.handle.net/10589/151136