Browsing by Author "Lopretti, Mary"
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- Bio-based composite materials from olive stonePublication . Sibaja, María; Alvarado, P.; Jiménez, L.; Rojas, Orlando J.; Barreiro, M.F.; Cateto, Carolina; Rodrigues, Alírio; Lopretti, MaryThe present work describes the methodology used for the preparation and characterization of composite samples prepared by mixing various percentages of olive stone flour in a polyester resin matrix. A study on the chemical-physical properties of the olive stone is reported, as well as, a set of tests to evaluate the mechanical properties of the manufactured products obtained. Biodegradation studies were carried out on the obtained composite materials.
- Bio-based composite materials from olive stonePublication . Sibaja, María; Alvarado, P.; Jiménez, L.; Rojas, Orlando J.; Barreiro, M.F.; Cateto, Carolina; Rodrigues, Alírio; Lopretti, MaryThe present work describes the methodology used for the preparation and characterization of composite samples prepared by mixing various percentages of olive stone flour in a polyester resin matrix. A study on the chemical-physical properties of the olive stone is reported, as well as, a set of tests to evaluate the mechanical properties of the manufactured products obtained. Biodegradation studies were carried out on the obtained composite materials.
- Biodegradation study of I lignin-based rigid polyrethane foamsPublication . Lopretti, Mary; Cateto, Carolina; Barreiro, M.F.; Ottati, Carolina; Rodrigues, Alírio; Belgacem, Mohamed NaceurPolyurethanes are considered as one of the most versatile polymeric materials offering a wide range of products with applications in diverse sectors. Rigid polyurethane (RPU) foams belong to this class of products and represent a commercially important class of expanded materials. In the present work RPU foams have been prepared from lignin-based polyols (LP) obtained by oxypropylation of two technical lignins (Alcell and Indulin AT) and biodegradability evaluated using respirometry tests in liquid and solid media. A RPU foam produced from a commercial polyether polyol (CP) based on sorbitol (Lupranol® 3323) was used as reference. Lignin biodegradation by P. chrysogenum, T. harzianum, T. reesei, T. versicolor and P. chrysosporium fungi was tested. Respirometry tests (in liquid and solid media) were performed and foam’s biodegradation evaluated based on the produced CO2.
- Biorefinery of Lignocellulosic and Marine Resources for Obtaining Active PVA/Chitosan/Phenol Films for Application in Intelligent Food PackagingPublication . Lopretti, Mary; Batista-Menezes, Diego; Rezende, Stephany; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Vega-Baudrit, Jose RobertoThis study focuses on the extraction of phenolic compounds from the fermentation of Phanerochaete chrysosporium and Gloeophyllum trabeum. The main goal was to synthesize phenol/chitosan microspheres and PVA films and characterized using FTIR, TGA, DSC, SEM, and mechanical tests to evaluate their physical, chemical, and mechanical properties for antimicrobial packaging applications. Homogeneous chitosan microspheres loaded with lignin-derived phenols were obtained, showing controlled release of antimicrobial compounds. The incorporation of phenolic microspheres into PVA/chitosan films resulted in significant improvements in mechanical properties: the films exhibited an elastic modulus of 36.14 ± 3.73 MPa, tensile strength of 12.01 ± 1.14 MPa, and elongation at break of 65.19 ± 5.96%. Thermal tests revealed that chitosan-containing films had enhanced thermal stability, with decomposition temperatures (T10) reaching 116.77 ◦C, compared to 89.28 ◦C for pure PVA. In terms of antimicrobial activity, PVA/chitosan/phenol films effectively reduced Lactobacillus growth and milk acidity, maintaining quality for up to 96 h at room temperature, outperforming controls with acetic acid and H2O2. The films also inhibit yeast growth for one week. In conclusion, phenols can be effective antimicrobial agents in dairy, but their use should be monitored. Additionally, PVA/chitosan-phenol films offer biodegradability, antimicrobial properties, and sustainability for diverse applications.
- Chitin and chitosan as sources of biocompatible polymers for microencapsulation and membranes productionPublication . Lopretti, Mary; Damboriarena, A.; Ottati, C.; Oliveira, A.; Sibaja, María; Zamora-Mora, V.; Solano, M.M.; Barreiro, M.F.The microencapsulation process of agents with biological activity such as, DNA, pharmaceuticals, proteins, probiotics and enzymes could be defined, from the technological point of view, as the coating process of those agents, under a molecular form, as solid particles, or as liquid globules, with materials of different nature, that gives particles of micrometric size. One of the most used natural polymers for the production of microspheres is chitosan (β-1,4-glucosamine). This polycationic biopolymer, is the chitin soluble form (deacetylated form), a linear polymer constituted by N-acetylglucosamine residues, obtained from the exoskeleton of crustaceans, for example from shrimps. In this work, different methodologies have been assayed for the production of chitosan microspheres and microcapsules. The morphology of the produced microcapsules was evaluated by optical and scanning electron microscopy. Stability and liberation studies of the encapsulated agent have been also performed. Concerning the membranes, it was evaluated the production of chitosan and chitosan-collagen membranes. Both types were also analysed by SEM.
- Lignin-based rigid polyurethane foams with improved biodegradationPublication . Cateto, Carolina; Barreiro, M.F.; Ottati, Carolina; Lopretti, Mary; Rodrigues, Alírio; Belgacem, Mohamed NaceurRigid polyurethane (RPU) foams have been synthesized using lignin-based polyols obtained by oxypropylation of four distinct lignins (Alcell, Indulin AT, Curan 27-11P, and Sarkanda). Polyol formulations with two lignin/propylene oxide/catalyst content (L/PO/C) ratios were chosen (30/70/2 and 20/80/5). RPU foams have been prepared with a polyol component that incorporates the lignin-based one at contents ranging from 25 to 100%. A 100% commercial polyol-based (Lupranol! 3323) RPU foam was also prepared and used as the reference. RPU foams were characterized in terms of density, compressive modulus, and conductivity. Cell morphology and size estimation were accessed by scanning electron microscopy. Moreover, biodegradation of the Alcell- and Indulin AT-based foams was evaluated using respirometry tests in liquid and solid media. The Alcell- and Indulin AT-based polyols together with the 20/80/5 Curan 27-11P-based one led to RPU foams with properties quite similar to those of the reference homolog. Biodegradation seems to be, particularly, favored if using Indulin AT-based polyols mixed with Lupranol! 3323.
- Microencapsulación de compuestos de actividad biologicaPublication . Lopretti, Mary; Barreiro, M.F.; Fernandes, Isabel P.; Damboriarena, A.; Ottati, C.; Oliveira, A.La microencapsulación de compuestos de actividad biológica (ADN, fármacos, proteínas, probióticos, enzimas, etc.), desde el punto de vista tecnológico podría definirse como el proceso de recubrimiento de dichos compuestos, bajo la forma de moléculas, partículas sólidas o glóbulos líquidos, con materiales de distinta naturaleza, para dar lugar a partículas de tamaño micrométrico. Uno de los polímeros naturales más utilizados para la producción de microesferas es el quitosano. Diversos métodos han sido propuestos para la producción de microcápsulas divididos en tres grupos: procesos físicos, procesos químicos y procesos físico-químicos. En el presente trabajo se ensayaron distintas metodologías para la producción de microesferas y micropartículas de quitosano. Según la metodología empleada se obtuvieron distintos tipos de esferas en lo que respecta a tamaño y densidad. Las micropartículas obtenidas se evaluaron mediante microscopía óptica, electrónica de barrido, así como se realizó la evaluación de su estabilidad y liberación del agente encapsulado.
- Microesferas de quitosano como potenciales transportadores de ácidos nucleicos y otros bioactivosPublication . Olivera, A.; Barreiro, M.F.; Lopretti, MaryEn este trabajo se prepararon microesferas de quitosano cargadas con ADN comercial como prototipo de sistemas de liberación de ácidos nucleicos. Para preparar las microesferas se utilizó una metodología basada en la preparación de una emulsión agua en aceite (w/o) seguida de entrecruzamiento con glutaraldehído. Las microesferas producidas fueron caracterizadas desde un punto de vista morfológico (HRSEM), evaluadas en cuanto al tamaño (SEM y citometría de flujo) y utilizadas para determinar el perfil de descarga de ADN. Se obtuvieron microesferas con una estructura porosa y con tamaño entre 1 y 20 μm de diámetro (SEM), destacándose una población de partículas individualizadas alrededor de 45% (en número) entre las 6 y 12 μm, según los datos aportados por la citometría de flujo. En cuanto al perfil de liberación en medio a valor de pH fisiológico se observó una liberación rápida, siendo que durante la primera hora 85% del principio activo había sido liberado alcanzándose 100% al final de dos horas.
- Obtención de un material compuesto termorrígido utilizando broza de semilla de aceitunaPublication . Jiménez, L.; Barreiro, M.F.; Cateto, Carolina; Rodrigues, Alírio; Sibaja, María; Lopretti, MaryEl presente trabajo describe la metodología de preparación de materiales compuestos utilizando diferentes porcentajes de broza de semilla de aceituna con resina poliéster insaturada comercial. Se trabajó con el desecho en forma de harina para mejorar la dispersión y se evalúo el efecto de la adición del mismo mediante análisis mecánicos y densidad aparente.
- Produccion de “CARRIERS” biocompatibles para aplicaciones en la industria farmacêuticaPublication . Olivera, A.; Lopretti, Mary; Barreiro, M.F.El quitosano, β-1-4 2-amino-2-deoxi-D-glucosa o D-glucosamina es un polisacárido con excelentes propiedades biológicas. La carga positiva que se produce en medio ácido como resultado de la protonación del grupo amino presente en cada unidad glucosamina, le confiere solubilidad en medio acuoso y es motivo de su actividad biocida. Este polímero biocompatible y biodegradable encuentra diversas aplicaciones en el área biomédica como vehículo para la entrega y descarga controlada de fármacos. El objetivo de este trabajo se centró en estudiar la compatibilidad y el comportamiento de proteínas y ADN con este tipo de matriz, con la meta de lograr la inserción de estos sistemas en el sector productivo. La metodología y técnicas de análisis empleadas, nos permitieron estudiar la distribución del componente microencapsulado en el volumen completo de estos sistemas, calcular el porcentaje de liberación y determinar la cinética de descarga.