Banca de DEFESA: REGIAMARA RIBEIRO ALMEIDA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : REGIAMARA RIBEIRO ALMEIDA
DATE: 17/11/2023
TIME: 13:30
LOCAL: online
TITLE:
Development of stimulus-responsive modified chitosan hydrogels for controlled delivery of thymol: Potential application in the control of dermatophytosis
KEY WORDS:
Fungal chitosan. Hydrogel. Dermatophytosis
PAGES: 125
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Polímeros e Colóides
SUMMARY:
In order to enable the applicability of chitosan as an antifungal agent, soil fungi were isolated and identified to be used in its production. The results indicate high viability of the isolated strains for the production of fungal chitosan (FCS), obtaining a maximum yield of 40.59 mg chitosan/g of dry biomass. The chitosans obtained were characterized by IR-ATR and 13C NMRSS. They showed high degrees of deacetylation (GD), ranging from 68.8% to 88.5%. Compared to crustacean chitosan, those from R. stolonifer and C. elegans had lower viscosimetric molar masses (26.23 and 22.18 kDa). At the same time, the molar mass of chitosan M. pseudolusitanicus L. presented a value coinciding with that classified as having low molar mass. Regarding the in vitro antifungal potential against the dermatophyte fungus Microsporum canis (CFP 00098), fungal chitosans showed antifungal properties, inhibiting mycelial growth by up to 62.81%. Despite the diversity of properties presented by chitosan, its application in the incorporation of bioactive compounds may be limited. Thus, chemical modifications were made to its structure in order to obtain hydrogels sensitive to pH/temperature to be applied in a release system. Through IR-ATR and 13C NMRSS analysis, the coupling of the polymers PMEO2MA and P(MEO2MA-co-DPA) into the chitosan polymer chain was verified. The hydrogels obtained showed a high degree of swelling of up to 90% in 90 minutes. It was also observed that the degree of PDPA coupling in the material influences its swelling capacity. The more PDPA, the more swollen the material becomes at acidic pH. Furthermore, it was noted that the amount of PMEO2MA can also regulate the performance of the material in terms of its thermosensitivity. It was found that the CS-g-P(MEO2MA-co-DPA) hydrogel showed greater affinity with the compound thymol and response at pH= 8.5 and at temperatures between 30-35 oC. Therefore, this material has characteristics that allow it to be used in applications linked to the release of active compounds in tissues with dermatophytosis. Therefore, we investigated the coupling capacity of FCS R. stolonifer in the P(MEO2MA-co-DPA) copolymer to obtain a hydrogel sensitive to pH/temperature. The synthesized hydrogel was characterized by IV-ATR and 13C RMNES, demonstrating the presence of functional groups and specific signals. Thermogravimetric analysis demonstrated that the FCS-g-P(MEO2MA-co-DPA) hydrogel presents thermal events distinct from FCS. Based on the swelling profile, it was possible to observe the hydrogel's response at pH=8.5 and a temperature close to body temperature with a reduction in its volume. The FCS-g-P(MEO2MA-co-DPA) hydrogel showed affinity for the compound thymol with an incorporation efficiency (IE) of 77%. When carrying out the thymol release kinetics test, behavior controlled by the Korsmeyer-Peppas kinetic model was observed, with high R2 values (R2 > 0.94). The evaluation of the in vitro antifungal potential against the dermatophyte fungus M. canis provided important results, in which inhibition of up to 85% of its mycelial growth was observed. Thus, this study suggests the potential of the FCS-g-P(MEO2MA-co-DPA)thymol hydrogel for applications in the control of dermatophytosis caused by the fungus M. canis.
BANKING MEMBERS:
Presidente - 1727278 - LUIZ GUSTAVO DE LIMA GUIMARAES
Interno - 1677150 - ARNALDO CESAR PEREIRA
Externa ao Programa - 2254152 - MAIRA NICOLAU DE ALMEIDA
Externa à Instituição - SARA SILVEIRA VIEIRA BERTOLI - UFF
Externa à Instituição - RAQUEL SILVA ARAÚJO - UFOP