Untitled

Funder

Organizational Unit

Publications

Preparation and Characterization of Films Based on a Natural P(3HB)/mcl-PHA Blend Obtained through the Co-culture of Cupriavidus Necator and Pseudomonas Citronellolis in Apple Pulp Waste

Publication . Rebocho, Ana Teresa; Pereira, João R.; Neves, Luísa A.; Delgado Alves, Vitor; Sevrin, Chantal; Grandfils, Christian; Freitas, Filomena; Reis, Maria A.M.

The co-culture of Cupriavidus necator DSM 428 and Pseudomonas citronellolis NRRL B-2504 was performed using apple pulp waste from the fruit processing industry as the sole carbon source to produce poly(3-hydroxybutyrate), P(3HB) and medium-chain length PHA, mcl-PHA, respectively. The polymers accumulated by both strains were extracted from the co-culture’s biomass, resulting in a natural blend that was composed of around 48 wt% P(3HB) and 52 wt% mcl-PHA, with an average molecular weight of 4.3 x 10 5 Da and a polydispersity index of 2.2. Two melting temperatures (Tm) were observed for the blend, 52 and 174 ºC, which correspond to the Tm of the mcl-PHA and P(3HB), respectively. P(3HB)/mcl-PHA blend films prepared by the solvent evaporation method had permeabilities to oxygen and carbon dioxide of 2.6 and 32 Barrer, respectively. The films were flexible and easily deformed, as demonstrated by their tensile strength at break of 1.47 +- 0.07 MPa, with a deformation of 338 +- 19% until breaking, associated with a Young modulus of 5.42 +- 1.02 MPa. This study demonstrates for the first time the feasibility of using the co-culture of C. necator and P. citronellolis strains to obtain a natural blend of P(3HB)/mcl-PHA that can be processed into films suitable for applications ranging from commodity packaging products to high-value biomaterials

2020Journal article

Open access

Chitin-glucan complex – Based biopolymeric structures using biocompatible ionic liquids

Publication . Ferreira, Inês C.; Araújo, Diana; Voisin, Pierre; Delgado Alves, Vitor; Rosatella, Andreia A.; Afonso, Carlos A.M.; Freitas, Filomena; Neves, Luísa A.

This work explores the novelty of dissolving chitin-glucan complex (CGC), from two fungal strains, Komagataella pastoris (CGCP) and Aspergillus niger (CGCKZ) (KiOnutrime-CG™), using biocompatible ionic liquids (ILs). Three cholinium-based ILs were tested, choline acetate, choline propionate and choline hexanoate. Although all tested ILs resulted in the dissolution of the co-polymer at a concentration of 5 % (w/w), distinct polymeric structures, films or gels, were obtained from CGCP and CGCKZ, respectively. CGCP films were dense, flexible and elastic, with high swelling capacity (> 200 %). The IL anion alkyl chain length influenced the polymeric structures’ properties, namely, the CGCP films elongation at break and swelling degree. CGCKZ resulted in weak gels. For both polymeric structures, exposure to the ILs under the dissolution conditions caused significant changes in the co-polymers’ chemical structure, namely, reduction of their glucan moiety and reduction of the degree of acetylation, thus yielding chitosan-glucan complexes (ChGC) enriched in glucosamine (53.4 ± 0.3–60.8 ± 0.3 %)

2020Journal article

Open access

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

2020Journal article

Open access

Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer

Publication . Araújo, Diana; Delgado Alves, Vitor; Marques, Ana C.; Fortunato, Elvira; Reis, Maria A.M.; Freitas, Filomena

Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Di erent NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9–50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials

2020Journal article

Open access

Characterization and biotechnological potential of extracellular polysaccharides synthesized by Alteromonas strains isolated from French Polynesia marine environments

Publication . Concórdio-Reis, Patrícia; Delgado Alves, Vitor; Moppert, Xavier; Guezennec, Jean; Freitas, Filomena; Reis, Maria A.M.

Marine environments comprise almost three quarters of Earth’s surface, representing the largest ecosystem of our planet. The vast ecological and metabolic diversity found in marine microorganisms suggest that these marine resources have a huge potential as sources of novel commercially appealing biomolecules, such as exopolysaccharides (EPS). Six Alteromonas strains from different marine environments in French Polynesia atolls were selected for EPS extraction. All the EPS were heteropolysaccharides composed of different monomers, including neutral monosaccharides (glucose, galactose, and mannose, rhamnose and fucose), and uronic acids (glucuronic acid and galacturonic acid), which accounted for up to 45.5 mol% of the EPS compositions. Non-carbohydrate substituents, such as acetyl (0.5–2.1 wt%), pyruvyl (0.2–4.9 wt%), succinyl (1–1.8 wt%), and sulfate (1.98–3.43 wt%); and few peptides (1.72–6.77 wt%) were also detected. Thermal analysis demonstrated that the EPS had a degradation temperature above 260 C, and high char yields (32–53%). Studies on EPS functional properties revealed that they produce viscous aqueous solutions with a shear thinning behavior and could form strong gels in two distinct ways: by the addition of Fe2+, or in the presence of Mg2+, Cu2+, or Ca2+ under alkaline conditions. Thus, these EPS could be versatile materials for different applications

2021Journal article

Open access