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Identifier 000460372
Title Responsive self-assembled peptides biomaterials and applications
Alternative Title Αποκρίσιμα αυτοοργανωμένα πεπτιδικά βιοϋλικά και εφαρμογές
Author Αποστολίδου, Χρυσάνθη-Πηνελόπη
Thesis advisor Μητράκη, Άννα
Reviewer Καλλιόπη, Βελώνια
Χατζηνικολαϊδου, Μαρία
Βαμβακάκη, Μαρία
Κουτσολέλος, Αθανάσιος
Κρετσόβαλη, Ανδρονίκη
Χαραλαμπίδης, Γεώργιος
Abstract This dissertation focuses on a class of materials that have been designed to exhibit a response to external stimuli such as light, pH, and metals. Commonly referred “as "smart materials," these substances present promising opportunities in a myriad of applications, from bioimaging to antimicrobial and anticancer therapies. Chapter I presents a general introduction about the peptides, one prime example of such materials. Due to the complex process of protein self-assembly, peptides play a pivotal role in research, serving as foundational components in the development of these novel materials. Biologically, peptides inherently self-assemble into a diverse array of organized structures using a bottom-up approach. Their inherent biocompatibility, biodegradability, and bio-functionality make them prime candidates for such investigations. This thesis is organized into three primary chapters, each centered on the specific stimulus to which these materials are responsive. Chapter 2 provides a deep dive into the ability of the dipeptide Fmoc-FF to be used as a light-responsive delivery vehicle. This peptide sequence possesses the inherent capacity to assemble into a three-dimensional hydrogel under physiological conditions. By encapsulating a chromophore molecule, this hydrogel gains the ability to respond to light and form antimicrobial structures. Our research specifically revolved around the investigation of such antimicrobial properties for hydrogels encapsulating porphyrins. In particular, we focused on the cationic porphyrins H2T(MePy)P(I4), Zn-T(MePy)P(I4), and Zn-T(MePy)P(Cl4), chosen for their distinct structural properties. Field-emission scanning electron microscopy (FESEM) was employed to analyze the morphology of both the scaffold and the embedded structures, which appeared as fibrillar. Additionally, we conducted mechanical tests to assess how the association with porphyrins affected their structural rigidity, revealing that the encapsulation of H2T(MePy)P(I4) produced the least rigid structure. Finally, the antimicrobial efficacy was assessed against both Gram-positive and Gram-negative bacterial strains. In Chapter 3, we present our work related to the development of fluorescent molecules for bioimaging. The broader target was to design trackers which could enter a cancer cell and hence allow its visual detection. In particular, we adopted peptide sequences containing histidine, which have the potential to coordinate with porphyrin-modified nitrilotriacetic acid (NTA) (chromophores) through metal chelation. This constituted our fluorescent probes tailored for bioimaging applications within cancer cells. Two peptides, namely RDSGAΙTIGH and the protected dipeptide Fmoc-FH, were at the center of our investigations. Both peptides inherently contain histidine residues in their structures. We confirmed the successful formation of the hybrids via FESEM imaging, and observed the peptide-porphyrin coordination generated structures which were morphologically different from those of the peptides or porphyrins alone. Moreover, this was complemented with UV-Vis spectroscopy measurements, which confirmed the successful coordination. Finally, the coordinated systems were studied for their ability to penetrate HeLa cancer cells. Finally, Chapter 4 reports our endeavor of assembling biocompatible nanoparticles carrying metal ions, which could be used for antibacterial or anticancer applications. In particular, we studied a cyclic-HF peptide as a coordinating agent for copper and zinc ions. FESEM imaging combined with EDX showed that the fibrillar structure formed by the peptide alone were modified into flower-like in the presence of copper ions indicating that CuO nanoparticles (NPs) were formed, and into spherical ones in the presence of zinc ions indicating that ZnO NPs were formed, which proved the successful coordination. Testing against Gram-positive and Gram-negative bacterial strains provided indication that the CuO NPs are slightly more efficient than ZnO NPs in terms of antimicrobial effect. Moreover, tests performed in tumoral environments showed an increased antitumor efficiency of both NPs, due to the low pH which favors the release of the metal ions. Synthesis of all porphyrin molecules was carried out by the members of Prof. Coutsolelos group, namely Georgios Charalambidis, Georgios Landrou, Vasilis Nikolaou, Manos Nikoloudakis, Eleni Glymenaki and Maria Kandyli, in the framework of a long term-collaboration of the two groups and part of the research was co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship, and Innovation, under the call RESEARCH – CREATE – INNOVATE (project Acronym : EPHESIAN, project code: T1EDK-01504).
Language English
Subject Hydrogels
Nanoparticles
Αυτοοργάνωση
Νανοσωματίδια
Πεπτίδια
Υδρογέλες
Issue date 2023-11-29
Collection   School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/1/2/c/metadata-dlib-1700130728-174461-20161.tkl Bookmark and Share
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