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Purification of Arabinoxylans from Corn Fiber and Preparation of Bioactive Films for Food Packaging
Publication . Serra, Maria; Weng, Verónica; Coelhoso, Isabel M.; Delgado Alves, Vitor; Brazinha, Carla
Corn fiber, a by-product of the starch industry, is presently incorporated in animal feed.
However, it has arabinoxylans as added-value components (besides ferulic acid) that should be
valorized. In this work, the raw material, a fraction enriched in arabinoxylans from corn fiber,
previously produced by alkaline extraction from corn fiber and pre-concentrated by ultrafiltration,
was further purified. The use of ultrafiltration operated in diafiltration mode (dia-ultrafiltration)
was evaluated for the purification of the arabinoxylans fraction. The objective was to maximize the
removal of the small contaminants from the fraction and to maximize the permeability and/or the
permeate flux, by selecting the relevant operating conditions involved in this process. The removal
of contaminants (%) was estimated when their apparent rejection stabilized. Edible films were
produced, from the resultant purified arabinoxylans fraction, using glycerol as plasticizer (30% dry
basis). Additionally, films with the incorporation of ferulic acid were developed, in order to obtain
barriers with antioxidant activity. The films were characterized in terms of mechanical properties,
antioxidant activity and permeability to water vapor. The films prepared presented a good potential
to be used as packaging for food products with low water content
Natural Multimerization Rules the Performance of Affinity-Based Physical Hydrogels for Stem Cell Encapsulation and Differentiation
Publication . Fernandes, Cláudia S.M.; Rodrigues, André L.; Delgado Alves, Vitor; Fernandes, Tiago G.; Pina, Ana Sofia; Roque, Ana Cecília A.
Tissue engineering and stem cell research greatly benefit from cell encapsulation within hydrogels as it promotes cell expansion and differentiation. Affinity-triggered hydrogels, an appealing solution for mild cell encapsulation, rely on selective interactions between the ligand and target and also on the multivalent presentation of these two components. Although these hydrogels represent a versatile option to generate dynamic, tunable, and highly functional materials, the design of hydrogel properties based on affinity and multivalency remains challenging and unstudied. Here, the avidin–biotin affinity pair, with the highest reported affinity constant, is used to address this challenge. It is demonstrated that the binding between the affinity hydrogel components is influenced by the multivalent display selected. In addition, the natural multivalency of the interaction must be obeyed to yield robust multicomponent synthetic protein hydrogels. The hydrogel’s resistance to erosion depends on the right stoichiometric match between the hydrogel components. The developed affinity-triggered hydrogels are biocompatible and support encapsulation of induced pluripotent stem cells and their successful differentiation into a neural cell line. This principle can be generalized to other affinity pairs using multimeric proteins, yielding biomaterials with controlled performance
Novel hydrogels based on yeast chitin-glucan complex: Characterization and safety assessment
Publication . Araújo, Diana; Delgado Alves, Vitor; Lima, Sofia A.C.; Reis, Salette; Freitas, Filomena; Reis, Maria A.M.
Chitin-glucan complex (CGC) was used for the first time for the preparation of hydrogels. Alkali solvent systems, NaOH and KOH solutions, either at 1 or 5 mol/L, were used for CGC dissolution using a freeze-thaw procedure (freezing at −20 °C and thawing at room temperature; four cycles). The CGC solutions thus obtained were subjected to dialysis that induced the spontaneous gelation of the biopolymer, yielding translucid hydrogels with a yellowish coloration. Although all CGC hydrogels exhibited porous microstructures, high water content (above 97%) and good mechanical properties, their morphology, viscoelastic properties and texture were influenced by the type of solvent system used for CGC dissolution, as well as by their ionic strength. The K-based hydrogels presented a less compact network with larger pores and exhibited lower elastic properties. The Na-based hydrogels, on the other hand, exhibited a denser structure with smaller pores and a stiffer gel structure. These results show that it is possible to prepare CGC hydrogels with differing characteristics that can be suitable for different applications. Furthermore, all hydrogels were non-cytotoxic towards L929 fibroblasts and HaCaT keratinocytes. This study demonstrates CGC can be used to prepare biocompatible hydrogels with properties render them promising biomaterials
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Fundação para a Ciência e a Tecnologia
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6817 - DCRRNI ID
Número da atribuição
154751