Banca de QUALIFICAÇÃO: AGATHA MARIA PELOSINE

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : AGATHA MARIA PELOSINE
Date: 10/12/2025
TIME: 09:00
LOCAL: https://meet.google.com/nhn-mafd-awa
TITLE:

Bioactives Release and Biointerfaces Interactions: The Journey of Nanostructured Systems Across Biological Barriers

PAGES: 100
BIG AREA: Ciências Biológicas
AREA: Biofísica
SUBÁREA: Biofísica de Processos e Sistemas
SUMMARY:

Despite decades of innovation, drug delivery still faces the challenge of achieving effective bioavailability. Biological barriers, such as skin and mucosa, can modulate drug absorption, distribution, and overall therapeutic efficiency. Based on this premise, the present thesis is organized in two sections: I) a review exploring how biological barriers modulate the release and permeation of bioactive compounds, and II) the development of polymeric films for skin delivery. Sustained and controlled-release formulations are strategies to address bioavailability. While sustained-release systems prolong drug action by slowing absorption, controlled-release design aim to deliver the compound at a predetermined, consistent rate. Current innovations in this field seek to integrate material design with biological interface understanding, advancing systems capable of overcoming or adapting to the complexity of biodynamic barriers. In this context, oxidative stress represents a relevant biological condition. Driven by an excess of reactive oxygen species (ROS), contributes to molecular and cellular damage. Gallic acid (GA), a phenolic antioxidant, is limited by its instability and potential toxicity. The incorporation of GA into polymeric films was proposed to overcome these drawbacks to enhance its protective activity and enable sustained release. Films were prepared by blade coating hydrogels composed of poly(vinyl alcohol) and xanthan gum (PVA:XA) in ratios of 9:1, 8:2, and 7:3, containing 3 or 6 mg mL⁻¹ of GA. SEM analysis revealed one smooth surface and one rough surface, with an average thickness of 40-60 µm. Mechanical analysis showed that increasing XA content enhanced gel strength and viscosity (7:3-a = 51.4 Pa·s-n, while 9:1-b = 1.3 Pa·s-n). FTIR spectra indicated polymer interactions: in the 7:3-a formulation, the O-H region appeared broader and the carboxylate bands of XA were more prominent, whereas in 9:1-b the 1142 cm⁻¹ band was dominant. Dissolution followed Higuchi kinetics (R² = 0.68–0.87) and non-Fickian diffusion, indicating sustained release. Permeation assays using Strat-M® membranes yielded fluxes of 0.13-0.40 µg·cm⁻²·h⁻¹, modulated by the polymer ratio and GA loading. DPPH assays confirmed preserved antioxidant activity, with GA-loaded films achieving 70-80% inhibition within 50 min. Cell viability tests using HaCaT keratinocytes demonstrated high biocompatibility of PVA and XA. GA alone exhibited an IC₅₀ of 47.1 µg mL⁻¹; film extracts caused cytotoxicity only at the highest concentrations. When these results were compared with the permeation data, the amount of GA able to cross the barrier membrane corresponded to the safe concentration (~25% viability threshold). Altogether, this work contributes to advancing polymer-based delivery platforms that adapt to biological complexity, offering promising perspectives for skin delivery and antioxidant therapies.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1623562 - RODRIGO LUIZ OLIVEIRA RODRIGUES CUNHA
Membro Titular - Examinador(a) Externo à Instituição - CARLOTA DE OLIVEIRA RANGEL YAGUI - USP
Membro Titular - Examinador(a) Externo à Instituição - MARLUS CHORILLI - UNESP
Membro Suplente - Examinador(a) Interno ao Programa - 2605490 - SERGIO DAISHI SASAKI
Membro Suplente - Examinador(a) Externo à Instituição - ARYANE ALVES VIGATO