Banca de QUALIFICAÇÃO: LILIAN MARTINS NASCIMENTO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LILIAN MARTINS NASCIMENTO
DATE: 15/08/2024
TIME: 14:00
LOCAL: Remoto
TITLE:

Incorporation of Thiazine Compounds in Fabrics for Light-Activated Microbicidal Action

PAGES: 60
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SPECIALTY: Superfícies e Interfaces; Películas e Filamentos
SUMMARY:

Considering the increasing appearance of resistant bacteria and the potential for the emergence of new pandemics, it is important to have preventive strategies for contamination and infection. Developing microbicidal materials constitutes an efficient strategy for preventing bacterial and viral infections. In this study, we investigated the microbicidal potential of dyes containing the phenothiazine nucleus capable of generating stable free radicals that could be repopulated upon exposure to UV and visible light. The effectiveness of cation radicals adsorption was demonstrated by advanced analytical techniques, including electron paramagnetic resonance (EPR), UV-visible, and FT-Raman spectroscopies that confirmed the presence of cation radicals in the fabrics, even after washing and re-exposure to light. Fabrics stained with the commercial phenothiazine dye sulfur black, 10H-phenothiazine, and fluphenazine, models of phenothiazinic compound, were tested. EPR measurements showed that all fabrics had the formation of stable free radicals when subjected to irradiation with visible and UV light. However, only the fabric treated with 10H-phenothiazine and fluphenazine exhibited efficient microbicidal action against bacteria and viruses. Exposure of these fabrics to phosphatidylcholine liposomes, a biological membrane model, promoted complete quenching of the 10H-phenothiazine and fluphenazine radical cation and only partial reduction of the sulfur black radical cation. The analysis of monomol emission of singlet oxygen by fabrics treated with the phenothiazines showed that only the fabric treated with sulfur Black did not exhibit the monomol singlet oxygen spectrum. Considering that damage to the lipid fraction of membranes is crucial for the microbicidal action of fabrics treated with phenothiazines, the present study suggests that the ability to generate singlet oxygen that can travel from the photosensitizing source to the membranes of microorganisms has an important contribution to the microbicidal action of these compounds in fabrics. This study paves the way for the design of new fabric dyes that conciliate colors with microbicide action.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1671688 - ANDRE SARTO POLO
Membro Titular - Examinador(a) Externo ao Programa - 2605420 - MARIA CRISTINA CARLAN DA SILVA
Membro Titular - Examinador(a) Externo ao Programa - 1939561 - FERNANDO HEERING BARTOLONI
Membro Titular - Examinador(a) Externo à Instituição - SILGIA APARECIDA DA COSTA - USP
Membro Suplente - Examinador(a) Externo ao Programa - 1623774 - KARINA PASSALACQUA MORELLI FRIN
Membro Suplente - Examinador(a) Externo ao Programa - 1674592 - TIAGO RODRIGUES
Membro Suplente - Examinador(a) Externo à Instituição - SIRLENE MARIA DA COSTA - USP