Percorrer por autor "Vitorino, Carla"
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- Lignin extraction from waste pine sawdust using a biomass derived binary solvent systemPublication . Magalhães, Solange; Filipe, Alexandra; Melro, Elodie; Fernandes, Catarina; Vitorino, Carla; Alves, Luís; Romano, Anabela; Rasteiro, Maria G.; Medronho, Bruno; MDPILignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.
- Repurposing bacterial lysates: Engineering inhalable locust bean gum microparticles for respiratory infection preventionPublication . da Silva, Joana Pinto; Berzosa, Melibea; Chiarentin, Lucas; Delgado-López, Alberto; Almeida, Maria Patricia; Vitorino, Carla; Figueiras, Ana; Rosa da Costa, Ana M; Gamazo, Carlos; Grenha, AnaThis study explores the development of inhalable microparticles containing bacterial lysates (BL) from multiple relevant bacterial species that include Staphylococcus aureus, Streptococcus pyogenes and Klebsiella pneumoniae, and locust bean gum (LBG) for pulmonary immunization against respiratory infections. LBG, a galactomannan, was chosen for its mucoadhesive properties and affinity for antigen-presenting cells. Microparticles were prepared by spray-drying, testing different LBG:BL ratios. The morphological analysis revealed convoluted microparticles, and BL association efficiency up to 81 % was determined. Antigenic assays confirmed that bacterial antigens of S. pyogenes, used as reference, remained preserved on the microparticles despite the applied processing conditions. The aerodynamic analysis showed that lower BL content (LBG:BL = 10:0.2, w/w) produced more suitable particles for pulmonary delivery, with 4.6 μm mass median aerodynamic diameter (MMAD) and 29 % fine particle fraction (FPF). Fluorescence microscopy confirmed uniform distribution of BL within the LBG matrix and LBG microparticles demonstrated superior adhesive properties compared to controls. Sustained release of BL from microparticles was observed in vitro, reaching around 80 % after 6 h, which increased to around 85 % after 24 h. Cytotoxicity studies showed appropriate cell viability at physiologically relevant concentrations (around 70 % or more). These findings suggest that LBG-based microparticles loaded with BL have potential to be explored as inhalable formulation for prevention of respiratory infections, offering targeted delivery and prolonged antigen presentation to enhance immune responses.
- Rheological and microstructural features of plant culture media doped with biopolymers: Influence on the growth and physiological responses of in Vitro-Grown Shoots of Thymus lotocephalusPublication . Coelho, Natacha; Filipe, Alexandra; Medronho, Bruno; Magalhães, Solange; Vitorino, Carla; Alves, Luís; Gonçalves, Sandra; Romano, AnabelaIn vitro culture is an important biotechnological tool in plant research and an appropriate culture media is a key for a successful plant development under in vitro conditions. The use of natural compounds to improve culture media has been growing and biopolymers are interesting alternatives to synthetic compounds due to their low toxicity, biodegradability, renewability, and availability. In the present study, different culture media containing one biopolymer (chitosan, gum arabic) or a biopolymer derivative [hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC)], at 100 or 1000 mg L−1, were tested regarding their influence on the growth and physiological responses of Thymus lotocephalus in vitro culture. Cellulose-based biopolymers (HEC and CMC) and gum arabic were used for the first time in plant culture media. The results showed that CMC at 100 mg L−1 significantly improved shoot elongation while chitosan, at the highest concentration, was detrimental to T. lotocephalus. Concerning only the evaluated physiological parameters, all tested biopolymers and biopolymer derivatives are safe to plants as there was no evidence of stress-induced changes on T. lotocephalus. The rheological and microstructural features of the culture media were assessed to understand how the biopolymers and biopolymer derivatives added to the culture medium could influence shoot growth. As expected, all media presented a gel-like behaviour with minor differences in the complex viscosity at the beginning of the culture period. Most media showed increased viscosity overtime. The surface area increased with the addition of biopolymers and biopolymer derivatives to the culture media and the average pore size was considerably lower for CMC at 100 mg L−1. The smaller pores of this medium might be related to a more efficient nutrients and water uptake by T. lotocephalus shoots, leading to a significant improvement in shoot elongation. In short, this study demonstrated that the different types of biopolymers and biopolymer derivatives added to culture medium can modify their microstructure and at the right concentrations, are harmless to T. lotocephalus shoots growing in vitro, and that CMC improves shoot length.