Daniel Sousa dos Santos

Rutin is a natural flavonoid whose larvicidal activity may be limited by its physicochemical properties. Here, a rutin–Zn material was prepared using a nominal 1:1 precursor molar ratio and evaluated against fourth-instar Aedes aegypti larvae. UV–Vis spectroscopy showed shifts of Band II from 258 to 270 nm and Band I from 361 to 439 nm. FTIR bands assigned to O–H and aromatic/conjugated vibrations shifted from 3391 to 3163 cm–1 and from 1601 to 1560 cm–1, respectively, while a new band at 694 cm–1 was tentatively associated with a Zn–O vibration. NMR revealed perturbations in several ligand environments, including an apparent C-5 shift from 157.5 to 161.6 ppm, supporting interaction between Zn2+ and oxygenated regions of rutin without defining a unique coordination site or stoichiometry. X-ray diffraction indicated limited structural reorganization and residual precursor-related crystalline features. The intensity-weighted hydrodynamic diameter increased from 226 ± 3 nm for free rutin to 1501 ± 19 nm for the rutin–Zn material, indicating the formation of larger solvated aggregates under the measurement conditions rather than an increase in primary particle size. After 48 h, LC50 decreased from 322 to 227 mg L–1 and LC90 from 701 to 420 mg L–1. These findings indicate that reaction with Zn2+ altered the physicochemical characteristics of rutin and was associated with moderately improved larvicidal activity under the tested laboratory conditions.

We explore the development of biodegradable poly(vinyl alcohol) (PVA) films loaded with silk fibroin (SF) functionalized with copaiba oleoresin (SFCO) for potential use in active food packaging. The films were characterized, showing significant improvements in both their physicochemical and nanomorphological properties. Films containing 10% SFCO exhibited superior mechanical strength, with a Young modulus of 145 MPa and an elongation at break of 385%, compared to the control film with 42 MPa and 314%, respectively. The films also demonstrated barrier properties, with water vapor transmission rates (WVTRs) as low as 25.95 g/h·m². Antimicrobial activity against Staphylococcus aureus and Escherichia coli was significantly improved, showing inhibition zones of up to 10 ± 1 mm and a minimum inhibitory concentration (MIC) of 100 µg∙mL⁻¹. Three-dimensional nanomorphological analysis via atomic force microscopy (AFM) showed increased roughness in films with higher SFCO content, with root mean square (RMS) roughness values ranging from 2.70 nm to 11.5 nm. These results highlight the potential of SFCO-loaded PVA films as robust, eco-friendly alternatives to conventional packaging materials. They provide improved mechanical and antimicrobial properties, essential for extending the shelf life of perishable foods and advancing sustainability in the packaging industry.

A análise da morfologia em nanoescala de filmes poliméricos utilizando Microscopia de Força Atômica (AFM) é essencial para entender as propriedades físicas e topográficas desses materiais. Este artigo de revisão tem como objetivo explorar de forma detalhada os principais parâmetros de superfície obtidos por AFM na análise de filmes poliméricos. São discutidas as equações matemáticas associadas a parâmetros importantes como rugosidade média, rugosidade quadrática média, curtose, assimetria, dimensão fractal, lacunaridade fractal, entropia de superfície, sucolaridade fractal e índice de Moran. Essas equações fornecem uma base teórica robusta para a interpretação dos dados obtidos e permitem uma análise minuciosa das características superficiais dos filmes. O artigo também ressalta a importância desses parâmetros como indicadores cruciais para avaliar a qualidade e a funcionalidade dos filmes poliméricos, proporcionando uma visão abrangente sobre como esses parâmetros podem afetar a performance e as propriedades dos materiais analisados. Essa abordagem contribui significativamente para a compreensão e aplicação dos filmes poliméricos em diversas áreas.

Biodegradable films based on poly(vinyl alcohol) (PVA) and bioactive substances have been receiving great attention in the food industry, as they offer an eco-friendly alternative to conventional packaging. In this context, we synthesized PVA (PVAF) films containing silk fibroin (SF) formulations functionalized with copaiba oleoresin (CO) for use as bioactive packaging. Four different formulations were prepared using the casting method, varying the SF-CO concentrations from 0 to 15% (v/v) in the PVA matrix. The samples were characterized regarding morphology, nanotexture, physicochemical, and barrier properties. SEM images revealed the uniform morphology of the films, and AFM data allowed the quantification of surface characteristics such as uniformity and homogeneity, confirming the uniform distribution of SF-OC in the PVA matrix. All films showed high water absorption power (more than twice their mass weight), and the incorporation of SF-CO did not change the water vapor permeability rate of PVAF. In contrast, the solubility of PVAF decreases with SF-CO content. FTIR and UV-vis spectra confirmed the presence of SF-CO in PVAF and indicated possible intermolecular interactions between PVA and SF-CO. Finally, our findings suggest that the incorporation of SF-CO into the PVA matrix is a viable alternative for producing eco-friendly packaging.