Banca de DEFESA: SANDRA VALÉRIA VASSILIADES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : SANDRA VALÉRIA VASSILIADES
DATA : 12/05/2020
HORA: 09:30
LOCAL: participação remota + https://zoom.us/j/92018111810?pwd=MitPRmNIRXExRWd6VnUxdzEyMExTZz09
TÍTULO:

Monofunctionalized porphyrins with L, L-diphenylalanine for potential application in photodynamic therapy.

PÁGINAS: 55
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Fotoquímica Orgânica
RESUMO:

Photodynamic therapy uses photosensitive organic compounds that, when irradiated by light,
trigger cellular oxidation processes. Thus, obtaining photoactive nanostructures capable of
promoting death in tumor cells is a potential target for the development of smart biomaterials.
In this work, four unpublished porphyrins monofunctionalized with diphenylalanine (FF), with
different substituents in the meso position were prepared and evaluated for their cytotoxicity
by cell viability assay, aiming at the application into co-self-assembly of porphyrin-FF and
Fmoc-FF to obtain a photoresponsive hydrogel. The compounds of interest (1-4) were
prepared with two main steps, the cyclization of the macro ring and the functionalization with
the dipeptide, the structures being confirmed by nuclear magnetic resonance (NMR). The
UV/Vis and fluorescence spectra showed that the 1-4 photophysical profile is compatible with
the literature. A porphyrin-FF/membrane interaction study was performed using DOPC
liposomes (1,2-dioleoyl-sn-glycero-3-phosphocholine), prepared by the extrusion method. The
membranes formed were titrated with a hybrid liposome formed by the 70:30 mixture of
DOPC and DOPE (1,2-dioleoyl-3-phosphatidylethanolamine), and it was observed that the
interaction of liposomes with functionalized porphyrins was more stabilized when compared
its non-functionalized version. Lifetime of porphyrin-FF was increased in the presence of the
membranes. The prepared compounds did not cause cytotoxicity with or without lighting
exposure, and the results obtained indicate that the porphyrins-FF have potential property of
cell proliferation, which was also observed by fluorescence microscopy. Hydrogels formed by
the self-assembly of Fmoc-FF and porphyrin-FF (0.5%, 5%, 10%, 20% and 30%), were prepared
in an H 2 O:DMSO mixture (9.5:0.5) and characterized by UV/Vis, fluorescence, rheology and
scanning electron microscopy (SEM). The photophysical properties of 1 and 2 remained
unchanged after the formation of the gels, the rheological profile also did not change with the
addition of porphyrin-FF, maintaining the hydrogel characteristics. In the SEM images, it was
observed that the Fmoc-FF fibers are elongated, and the addition of 1 and 2 caused the
formation of branches in the threads. The hydrogels were used as a cell adhesion matrix for
HEK293, and by fluorescence microscopy it was possible to observe that the cells were
adhered, and exposure for 10 minutes with a blue LED lamp, indicated the occurrence of cell
proliferation induction. Compounds 1-4 were obtained in average overall yield of 3% and were
characterized by NMR ( 1 H and 13 C), absorbance and emission spectroscopy. The study of the
interaction between porphyrin/membrane demonstrated that the addition of the peptide
portion led to greater stability and the liposome increased the lifetime. No cytotoxicity was
observed in 1-4 for HEK293 cells, and the results are indicative of induction of cell
proliferation. Hydrogels prepared from 1 and 2 self-assembly with Fmoc-FF preserve the
optical properties of porphyrins, and the increase in the concentration of the compounds did
not prevent the hydrogelation of the dipeptide. The hydrogel's rough surface did not hinder
cell adhesion, and with fluorescence microscopy it was possible to notice that after light
exposure, there was an increase in cell growth. These promising results indicate the possibility
of using these biomaterials as photoresponsive dressings, for instance.
In a complementary work, hydrogels of Fmoc-FF and tetraporphyrins were prepared, which
were characterized by UV/Vis, fluorescence, rheology, SEM and electronic paramagnetic
resonance (EPR) was used to evaluate the formation of singlet oxygen. Tetraphenylporphyrin
(TPP), tetracarboxyporphorin (TCP), tetrahydroxyporphine (THP) and tetrapyridylporphyrin
(TPyP) were obtained as a by-product of the cyclization reaction and characterized by 1H-NMR.

The hydrogels were prepared with a solvent mixture of H 2 O:DMSO (9:1). The prepared
hydrogels had their photophysical characteristics preserved and the addition of
tetraporphyrins did not alter the rheological properties or the hydrogel morphology. It was
possible to observe the formation of 1 O 2 for the compounds TFP, TCP and THP (high
concentration). And a comparative study with tetraporphyrins in gel and solution, showed that
the confinement of the compounds causes a modulation in the formation of 1O2.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1544341 - WENDEL ANDRADE ALVES
Membro Titular - Examinador(a) Interno ao Programa - 1939561 - FERNANDO HEERING BARTOLONI
Membro Titular - Examinador(a) Externo ao Programa - 1604147 - LEONARDO JOSE STEIL
Membro Titular - Examinador(a) Externo ao Programa - 1672728 - ANA CAROLINA SANTOS DE SOUZA GALVAO
Membro Titular - Examinador(a) Externo à Instituição - ALESSANDRO RODRIGUES - UNIFESP
Membro Suplente - Examinador(a) Interno ao Programa - 1544365 - GISELLE CERCHIARO
Membro Suplente - Examinador(a) Externo ao Programa - 1676364 - JULIANA MARCHI
Membro Suplente - Examinador(a) Externo à Instituição - DANIEL PEREZ VIEIRA - IPEN