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| Identifier |
000449063 |
| Title |
Photoactive cyclodextrin derivatives for drug delivery |
| Alternative Title |
Λειτουργικά παράγωγα κυκλοδεξτρινών με φωτοδραστικά μόρια για μεταφορά φαρμάκων |
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Author
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Παναγιωτάκης, Στυλιανός Μ
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Thesis advisor
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Γιαννακοπούλου, Κωνσταντίνα
Κουτσολέλος, Αθανάσιος
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Reviewer
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Μητράκη, Άννα
Σμόνου, Ιουλία
Παυλίδης, Ιωάννης
Σπυρούλιας, Γεώργιος
Χατζηκακού, Σωτήριος
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| Abstract |
In the search for photosensitizers with chemical handles to facilitate their integration into complex drug delivery nanosystems, new, unsymmetrically substituted, water insoluble meso-tetraphenylporphyrin (TPP) and meso-tetra(m-hydroxyphenyl)porphyrin (mTHPP) derivatives bearing one carboxyalkyl side chain of variable length were synthesized (TPPCOOHCx). It was found that permethyl-β-cyclodextrin (pMβCD) is their ideal monomerizing host and highly efficient shuttle to transfer them into water. New assembly modes of the extremely stable (Kbinding 1012M-2) 2:1 supramolecular complexes were identified. Moreover, is was shown that the complexes are photostable and do not disassemble in Fetal Bovine Serum (FBS)-containing cell culture media for 24 h. Incubation of breast cancer MCF-7 cells with the complexes resulted in intense intracellular fluorescence, strongly enhanced in the endoplasmic reticulum (ER). The complexes displayedhigh photokilling efficiency (~90%) and low dark toxicity. Overall, pMβCD stands out as a very capable molecular isolator of mono-carboxyalkyl-arylporphyrinsthat increases uptake and modulates their localization in the cells. The most efficient porphyrins are envisaged as suitable photosensitizers that can be linked to biocompatible drug carriers for photo-and chemo-therapy applicationsand this was pursued, next. Aiming the development of photoactive systems of higher complexity and functionality, the above carboxyalkyl-triphenylporphyrins (TPPCOOHCx) were connected to β-cyclodextrin (βCD) via alkyl chains of variable length (2, 5 and 11 C-atoms) to yield three new conjugates (TPPOCNHbmCx). The aspiration has been to capitalize on the strong amphiphilic character of the conjugates to construct drug-carrying photosensitizers that can be functionally integrated into advanced delivery nanosystems. It was found that all conjugates self-assemble similarly, to form mainly populations of ~60 nm nanoparticles (NPs), as shown by a range of methods. These NPs remain stable for at least 3 days in Phosphate Buffer Siline (PBS) solution. Moreover, the NPs also display similar photophysical properties, regardless of the length of the alkyl linkers, and upon irradiation they produce 1O2 atrates comparable or higher to a reference porphyrin mTHPP, while they exhibit sufficient photostability. Upon loading with selected anticancer drugs tamoxifen citrate (TamCit) and gemcitabine (GEM) the NPs grow in size up to ~150 nm due to un-twisting of the linker chains previously folded over the narrow βCD opening. Incubation of the NPs, alone or loaded with anticancer drugs, with human breast cancer cells MCF-7 resulted in confocal images with abundant, very intense spotted intracellular fluorescence, indicative of localization of the conjugates in membranes of endocytic vesicles and specifically lysosomes. Co-localization experiments and in-cell Förster Resonance Energy Transfer (FRET) with a lysotracker confirm the selective accumulation into these organelles. On the other hand, experiments with liposomes show that the NPs can be incorporated as monomers in artificial membranes with their βCD cavities available for guest inclusion. Photokilling experiments using MCF-7 cells incubated with drug-loaded NPs (TamCit and an N-adamantyl derivative of GEM) showed that the assemblies not only exert high toxicity (> 85 %) but also the cells cease to grow for at least 48 h, indicative of synergistic photo-triggered drug and 1O2 release and a manifestation of Photochemical Internalization (PCI). The most efficient conjugates (C2 and C5 chains) are therefore suitable to enable small molecule chemotherapeutics to be successfully integrated into PCI technology protocols. Supramolecular organization and self-assembly are the pillars of functionality of many nanosystems. The covalent conjugate (6-spirolactam rhodamine B-6-monodeoxy)-β-cyclodextrin (Rho-βCD) is assembled as a self-included, rigid nanostructure, identical in the crystalline state and in aqueous solution, as revealed by detailed X-ray and NMR analyses. Rho-βCDself-assembly is the result of an interesting reaction pathway, which partially de-aggregates Rho and disturbs the zwitterion ↔spirolactone equilibrium. Rho-βCD spirolactam not only is stable at pH 4.6, but also displays controllable photoswitching between the colored, fluorescent, zwitterionic open and the colorless, nonfluorescent closed structures, during several iterative cycles. After an initial drop in absorbance, the on-off process continues without further changes under our irradiation conditions, a consequence of the specific self-locked arrangement of Rho in the cavity. Rho-βCD exemplifies a water soluble photoresponsive nanosystem with improved photostability suggesting promising applications in super resolution bioimaging.
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| Language |
English |
| Subject |
Chemotherapeutics |
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Crystal structure |
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Endoplasmic Reticulum (ER) |
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Inclusion complexes |
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Monocarboxyalkyl-porphyrins |
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NMR |
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Nanoparticles (NPs) |
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Permethyl-β-cyclodextrin(pMβCD) |
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Photochemical Internalization(PCI) |
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Photokilling |
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Photoswitching |
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Porphyrin-cyclodextrin conjugates |
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Rhodamine B |
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Self-assembly |
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Self-inclusion |
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Spirolactam |
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Αυτό-εγκλεισμός |
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Αυτό-οργάνωση |
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Ενδοπλασματικό δίκτυο (ER) |
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Κρυσταλλοδομή |
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Μονοκαρβοξυαλκυλο-πορφυρίνες |
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Νανοσωματίδια (NPs) |
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Περμεθυλ-β-κυκλοδεξτρίνη(pMβCD) |
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Ροδαμίνη B |
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Σπειρολακτάμη |
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Συζεύγματα πορφυρίνης-κυκλοδεξτρίνης |
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Σύμπλοκα εγκλεισμού |
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Φωτοεναλλαγή |
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Φωτοτοξικότητα |
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Φωτοχημική ενσωμάτωση (PCI) |
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Χημειοθεραπευτικά |
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β-cyclodextrin(βCD) |
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β-κυκλοδεξτρίνη(βCD) |
| Issue date |
2022-07-04 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
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Type of Work--Doctoral theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/b/0/metadata-dlib-1655716484-733231-21431.tkl
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| Views |
386 |
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