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Identifier

000376588

Title

Σύνθεση βιοσυμβατών και βιοδιασπώμενων συζυγών πρωτεϊνης-πολυμερούς μέσω ενζυμικά καταλυόμενου πολυμερισμού διάνοιξης δακτυλίου.

Alternative Title

Synthesis of biocompatible and biodegradable protein-polymer conjugates through enzyme catalyzed ring opening polymerization.

Author

Δασκαλάκη, Ελευθερία Γεώργιος

Thesis advisor

Βελώνια, Κέλλυ

Reviewer

Αναστασιάδης, Σπύρος
Σμόνου, Ιουλία

Abstract

Aim of this study was the synthesis of a new generation of protein-polymer bio-conjugates which were designed to be biocompatible and biodegradable. The synthesis of these biohybrids was based on previous studies of the group of Dr. Velonia which proved the efficiency of the grafting from approach and was carried out using for the first time an enzyme catalyzed Ring Opening Polymerization (ROP) of ε-caprolactone and its derivatives. This new synthetic approach was developed with the aim to evolve the advantages of the grafting from Atom Transfer Radical Polymerization (ATRP) toward mild reaction conditions and absence of toxic catalysts that are intrinsic in enzymatic catalysis. Furthermore, the hydrophobic chain growth following this approach leads to the synthesis of polycaprolactone biohybrids, rendering the new generation of Giant Amphiphiles especially interesting as they are expected to combine self-assembly with biodegradability under specific conditions. In the future, these superstructures may find numerous applications such as nanoreactors or nanocontainers for drug delivery or/and drug release. We studied the ROP of ε-caprolactones using the lipase B from Candida antarctica in its immobilized form Novozym® 435. A ROP biomacroinitiator, BSA-PEG-OH, having an overall hydrophilic character was synthesized and was found able to initiate the propagation of the hydrophobic polyester chain through the lipase catalyzed grafting from approach. During this project a range of bio-conjugates was synthesized and characterized by chromatography, electrophoresis, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The reaction conditions were optimized by varying solvent, temperature and water content which, according to bibliography, are the determining factors for optimizing the reaction. The self-assembled architectures of the bio-conjugates were studied by electron microscopy. In addition, the enzymatic catalyzed degradation of these Giant Amphiphiles was studied and the reaction conditions were optimized under mild conditions. Overall, during this study we proved the ability of Novozym® 435 to catalyze the enzymatic synthesis of Giant Amphiphiles through a ROP grafting of caprolactones from a protein initiator. We also studied the reverse reaction, i.e. the enzymatic degradation of the polycaprolactone moiety of the Giant Amphiphiles, under mild conditions. Finally, we demonstrated the ability of these new biodegradable Giant Amphiphiles to self-assemble into well organized superstructures and to encapsulate guest molecules.

Language

Greek

Subject

Bioconjucates

Biohybrids

Biopolymers

Polymers enzymatic

Ring opening polymerization

Βιοπολυμερή

Βιοσυζυγή

Βιοϋβρίδια

Ενζυμική κατάλυση