Abstract |
The present Doctoral Thesis describes the synthesis of new chromophores, and
their utilization in photocatalytic and medical applications. Particularly, several water-
soluble porphyrins and carbon dots are examined as photosensitizers, combined either
with catalysts for hydrogen (H2) production or Fmoc-protected dipeptides for
antimicrobial and wound healing applications.
More specifically, the simple synthetic approaches, attractive photophysical
properties, and solubilization in the water of the prepared chromophores are the key
parameters for the presented applications. The characteristic Pyridyl groups in the
meso-position of the synthesized porphyrins offer water-solubility upon methylation.
Different central metal ions, such as zinc, tin, cobalt, and nickel transform the
properties of the resulting porphyrin derivatives. On the other hand, carbon dots as light
harvesters offer distinctive properties and low-cost preparation. Moreover, the
passivation of the surface of these materials with Nitrogen sources can modify their
properties.
This dissertation is divided into two main sections. The first section was
inspired by natural photosynthesis. More specific, water-soluble chromophores were
combined with molecular Cobalt and Nickel catalysts to transform protons into Η2.
Various factors that determine the efficiency of the photocatalytic system are
evaluated, in order to maximize H2 production. Namely, some representative
parameters that were explored are: the charge of the porphyrin derivatives, the buffer
solution, the light source, the ratio between the photosensitizer and the catalyst.
Furthermore, extensive photophysical and electrochemical investigation was
conducted in order to determine the mechanism of the phorocatalytic H2 production.
Interestingly, except for utilizing only commercial light sources, actual solar irradiation
uner sunlight was applied targeting to obtain important observations for future uses.
The next section deals with the incorporation of the water-soluble
chromophores in hydrogel networks formed by Fmoc-protected dipeptides, through
intermolecular interactions. The formatted hydrogels are used in advanced
antimicrobial applications in bacteria and worms such as C. elegance. Numerous
studies are carried out, such as cytotoxicity and visible light affection in the resulting
hydrogels.
Finally, the wound healing application of the formatted hydrogels on the Wistar
rat's skin is examined. The wound healing process is studied both in young and old
animals for a comprehensive results analysis. Controlling the effectiveness of the
resulting hydrogels will provide valuable results for future clinical studies.
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