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Identifier

000449678

Title

Σύνθεση, χαρακτηρισμός, και αυτοοργάνωση διπεπτιδίων με δυνητικές περιβαλλοντικές εφαρμογές

Alternative Title

Synthesis, characterisation and self-assembly of dipeptides in depollution applications

Author

Μητροπούλου, Κωνσταντίνα Κ.

Thesis advisor

Κουτσολέλος, Αθανάσιος

Reviewer

Μητράκη, Άννα
Παυλίδης, Ιωάννης

Abstract

Peptide-based hydrogels find recently a plethora of applications in fields such as drugdelivery, as well as groundwater remediation. In the case of drug-delivery in particular, the peptide-based hydrogels encapsulate pharmaceutical products and then release them inside the organism. The release is both targeted and controlled. Such a peptide-based hydrogel was designed and implemented during the presented thesis. Firstly, the dipeptide Fmoc-Phe-IleOH was synthesized through an innovative synthetic process that is both simple and quick, while the product is being isolated and cleaned easily and in high yields. We have subsequently studied the self-assembly of this dipeptide. According to the protocol of good/ bad solvent, which in this case were the solvents ethanol/ water respectively, the dipeptide forms well-structured hydrogels, consisting of fibril structures. We used this hydrogel in a 2 mg/ml peptide concentration and solvent ratio 2.5:7.5 (ethanol:water) to encapsulate the water-soluble porphyrin [H₂- TMePyP(I₄)] and assessed the release of the latter in aqueous environment at 36.6^ο C, in order to simulate the conditions in the human organism. We have, thus, established three key aspects of this release: a) the hydrogel releases approximately 79.36% of the initially absorbed water-soluble porphyrin within a timeframe of 24h; b) the hydrogel is being degraded after approximately 48h, which constitutes a useful property for drug delivery applications; c) the release of the drug reaches a plateau approximately 6h after the initiation of its release. Finally, we have examined the antimicrobial properties of our system, consisted of the hydrogel along with the encapsulated [H₂- TMePyP(I₄)]. The system was checked against bacteria E.coli under different light conditions, including both absence of light and lighting conditions. All the samples were proven to have antibacterial properties against E.Coli in absence of light but with no significant difference between them. On the other hand, under light the sample with the encapsulated porphyrin was proven to have significantly better antibacterial action than the sample of the dipeptide. The second part of the presented master thesis was oriented towards environmental remediation and included the design of a peptide-based hydrogel for the absorption of toxic organic dyes and metal ions in aqueous environments. The first step was the synthesis of the peptide-based hydrogel Fmoc-Phe-Leu-OH, following the same synthetic process as described above for Fmoc-Phe-Ile-OH dipeptide. We have afterwards examined the capacity of the dipeptide to form hydrogels and organogels according to the protocol of good/ bad solvent. It was proven that ethanol and water promote the formation of hydrogels, whereas DCM and hexane/ heptane promote the formation of organogels, both formations consisting of fibril structures. We used this hydrogel in a 2 mg/ml peptide concentration and solvent ratio 3:7 (ethanol:water) to examine its capacity to absorb toxic organic dyes and metal ions from aqueous environments and proved that 1ml of the given hydrogel can absorb within a timeframe of 3 days the 89.38% of 1ml Coomasie Brilliant Blue (20 μΜ), the 82.5% of 1ml Methylene Blue (3.2μΜ), the 85.35 % of 1ml Congo Red (10 μΜ), the 43.33% of 1ml metal ions Co²⁺ (0.1 M) and 58.85 % of 1ml metal ions Ni²⁺ (0.1 Μ). We have further examined the absorption capacity of the hydrogel against metal ions Ni²⁺ and Co²⁺ in cases of re-usage and found that the hydrogel maintains its high capacity for the first four cycles of re-usage. Finally, we have checked and confirmed the capacity of the dipeptide-based organogel to absorb petroleum products.. In conclusion, the dipeptides Fmoc-Phe-Ile-OH and Fmoc-Phe-Leu-OH were proven to form hydrogels offering a broad range of potential applications not only in pharmaceutics, but in environment remediation as well.

Language

Greek

Subject

Depollution hydrogels

Drug-delivery

Peptide hydrogels

Peptide organogels

Peptide synthesis

Porphyrin

Self-assembling peptides

Μεταφορά φαρμάκου

Πεπτιδικά organogels