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Antioxidant Migration Studies in Chitosan Films Incorporated with Plant Extracts
Publication . Souza, Victor Gomes Lauriano de; Rodrigues, Patricia Freitas; Duarte, Maria Paula; Fernando, Ana Luisa; MEtRICS - Centro de Engenharia Mecânica e Sustentabilidade de Recursos; DCTB - Departamento de Ciências e Tecnologia da Biomassa (ex-GDEH); CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Tech Science Press
The aim of this work was to develop an active biopolymer based on chitosan by incorporating natural antioxidants. Five essential oils (ginger, rosemary, sage, tea tree and thyme) and six hydro-alcoholic extracts (from ginger, green and black tea, kenaf leaves, rosemary and sage plants) were tested. Migration assays were carried out to evaluate the films’ activity, and total phenolic content and antioxidant activity were monitored in the simulant during storage. Interaction between natural compounds and polymeric matrix was evaluated by FTIR spectroscopy. The diffusion of the phenolic compounds was not detected in the films incorporated with hydro-alcoholic extracts (HAEs), indicating their entrapment in the chitosan. Migration was observed in the films with essential oils (EOs), and biobased films incorporated with ginger, sage or rosemary essential oils, presented the highest diffusion and antioxidant activity in the simulant, highlighting their functionality and potential to be used as food active packaging material
Paper-based nanoplatforms for multifunctional applications
Publication . Matias, M. L.; Nunes, D.; Pimentel, A.; Ferreira, S. H.; Borda D’Agua, R.; Duarte, M. P.; Fortunato, E.; Martins, R.; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MEtRICS - Centro de Engenharia Mecânica e Sustentabilidade de Recursos; DCTB - Departamento de Ciências e Tecnologia da Biomassa (ex-GDEH); John Wiley and Sons Ltd
In this work, zinc oxide (ZnO) and titanium dioxide (TiO2) nanostructures were grown on different cellulose paper substrates, namely, Whatman, office, and commercial hospital papers, using a hydrothermal method assisted by microwave irradiation. Pure ZnO and TiO2 nanostructures were synthesized; however, the growth of TiO2 above ZnO was also investigated to produce a uniform heterostructure. Continuous ZnO nanorod arrays were grown on Whatman and hospital papers; however, on office paper, the formation of nanoplates originating nanoflower structures could be observed. TiO2 nanoparticles homogeneously covered all the substrates, in some conditions forming uniform TiO2 films. Structural characterization was carried out by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy. The optical characterization of all the materials was carried out. The produced materials were investigated for multifunctional applications, like photocatalyst agents, bacterial inactivators, and ultraviolet (UV) sensors. To evaluate the photocatalytic activity under UV and solar radiations, rhodamine B was the model-test contaminant indicator and the best photocatalytic activity was achieved with Whatman paper. Hospital paper with TiO2 nanoparticles showed significant antibacterial properties against Staphylococcus aureus. ZnO-based UV sensors demonstrated a responsivity of 0.61 μA W-1.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/EMS/04077/2013