Percorrer por autor "Sousa, Sérgio C."
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- Can growth of nannochloropsis oculata under modulated stress enhance its lipid-associated biological properties?Publication . Sousa, Sérgio C.; Machado, Manuela; Freitas, Ana C.; Gomes, Ana M.; Carvalho, Ana P.Nannochloropsis oculata is well-recognized as a potential microalgal source of valuable compounds such as polyunsaturated fatty acids, particularly, eicosapentaenoic acid (EPA). The content and profile of these lipids is highly dependent on the growth conditions and can, therefore, be tailored through modulation of the growth parameters, specifically, temperature. Moreover, biological activities are composition dependent. In the present work, lipid extracts obtained from N. oculata, grown under constant temperature and under modulated temperature stress (to increase EPA content; Str) were characterized by GC-FID and several bioactivities were evaluated, namely, antioxidant (L-ORACFL), cytotoxic (MTT), adipolytic, anti-hepatic lipid accumulation (steatosis), and anti-inflammatory properties. Both extracts exhibited antioxidant activity (c.a. 49 µmol Troloxequivalent/mgextract) and the absence of toxicity (up to 800 µg/mL) toward colon and hepatic cells, adipocytes, and macrophages. They also induced adipolysis and the inhibition of triglycerides hepatic accumulation, with a higher impact from Str. In addition, anti-inflammatory activity was observed in the lipopolysaccharide-induced inflammation of macrophages in the presence of either extract, since lower levels of pro-inflammatory interleukin-6 and interferon-β were obtained, specifically by Str. The results presented herein revealed that modulated temperature stress may enhance the health effects of N. oculata lipid extracts, which may be safely utilized to formulate novel food products.
- Chitosan nanoparticles as bioactive vehicles for textile dyeing: a proof of conceptPublication . Costa, Eduardo M.; Silva, Sara; Machado, Manuela; Sousa, Sérgio C.; Tavaria, Freni K.; Pintado, ManuelaIn recent years bioactive textiles have risen to the forefront of consumers perception due to their potential protection against virus, fungi and bacteria. However, traditional textile staining is an eco-damaging process that and current methods of textile functionalization are expensive, complicated and with great environmental impact. With that in mind, this work sought to show a possible solution for this problematic through the usage of a novel one step textile dyeing and functionalization method based upon nanoencapsulated textile dyes (NTDs). To do so navy blue everzol NTDs were produced with chitosan, cotton dyed, characterized through FTIR and SEM and biological potential evaluated through biocompatibility screening and antimicrobial activity against skin pathogens. The data obtained showed that NTDs effectively dyed the target textile through a coating of the cotton fibre and that NTDs formed hydrogen bonds with the cellulose fibre via electrostatic interactions of the chitosan amino groups with cotton sulphate groups. From a biocompatibility perspective NTDs dyed cotton had no deleterious effects upon a skin cell line, as it promoted cellular metabolism of HaCat cells, while traditionally died cotton reduced it by 10%. Last but not least, NTDs dyed cotton showed significant antimicrobial activity as it reduced viable counts of MRSA, MSSA and A. baumannii between 1 and 2 log of CFU while traditional dyed cotton had no antimicrobial activity. Considering these results the novel method proposed shows is a viable and ecological alternative for the development of antimicrobial textiles with potential biomedical applications.
- Development of probiotic tablets using microparticles: viability studies and stability studiesPublication . Sousa e Silva, J. P.; Sousa, Sérgio C.; Costa, Paulo; Cerdeira, Emília; Amaral, Maria H.; Lobo, José Sousa; Gomes, Ana M. P.; Pintado, Maria M.; Rodrigues, Dina; Rocha-Santos, Teresa; Freitas, A. C.Alternative vectors to deliver viable cells of probiotics, to those conferring limited resistance to gastrointestinal conditions, still need to be sought. Therefore the main goal of the study was to develop tablets able to protect entrapped probiotic bacteria from gastric acidity, thus providing an easily manufacturing scale-up dosage form to deliver probiotics to the vicinity of the human colon. Whey protein concentrate microparticles with Lactobacillus paracasei L26 were produced by spray-drying and incorporated in tablets with cellulose acetate phthalate and sodium croscarmellose. The viability of L. paracasei L. 26 throughout tableting as well as its gastric resistance and release from the tablets were evaluated. Storage stability of L. paracasei L26 tablets was also performed by evaluation of viable cells throughout 60 days at 23 degrees C and 33% relative humidity. A decrease of approximately one logarithmic cycle was observed after the acid stage and the release of L. paracasei L26 from the tablets occurred only after 4 h in the conditions tested. Microencapsulated L. paracasei L26 in tablets revealed some susceptibility to the storage conditions tested since the number of viable cells decreased 2 log cycles after 60 days of storage. However, the viability of L. paracasei L26 after 45 days of storage did not reveal significant susceptibility upon exposure to simulated gastrointestinal conditions. The developed probiotic tablets revealed to be potential vectors for delivering viable cells of L. paracasei L26 and probably other probiotics to persons/patients who might benefit from probiotic therapy.
- Enhancing medium-chain fatty acid delivery through bigel technologyPublication . Machado, Manuela; Costa, Eduardo M.; Silva, Sara; Sousa, Sérgio C.; Gomes, Ana Maria; Pintado, ManuelaThis study presents the development and characterization of medium-chain fatty acid (MCFA)-loaded bigels, using coconut oil as the MCFA source. The bigels exhibited high oil binding capacity, ranging from 87% to 98%, effectively retaining MCFAs within the matrix, with lauric acid (C12) being the main component detected within the bigels at 178.32 ± 0.10 mg/g. Physicochemical analysis, including FTIR and scanning electron microscopy, confirmed stable fatty acid incorporation and a cohesive, smooth structure. The FTIR spectra displayed O-H and C=O stretching vibrations, indicating hydrogen bonding within the matrix, while the SEM images showed uniform lipid droplet distribution with stable phase separation. Thermal stability tests showed that the bigels were stable for 5 days at 50 °C, with oil retention and structural integrity unchanged. Rheological testing indicated a solid-like behavior, with a high elastic modulus (G′) that consistently exceeded the viscous modulus (G″), which is indicative of a strong internal structure. In simulated gastrointestinal digestion, the bigels achieved significantly higher MCFA retention than the pure oil, particularly in the gastric phase, with recovery percentages of 38.1% for the bigels and 1.7% for the oil (p < 0.05), suggesting enhanced bioavailability. Cell-based cytotoxicity assays showed low cytotoxicity, and permeability testing in a co-culture Caco-2/HT29-MTX model revealed a controlled, gradual MCFA release, with approximately 10% reaching the basolateral side over 6 h. These findings highlight MCFA-loaded bigels as a promising platform for nutraceutical applications; they provided stability, safety, and controlled MCFA release, with significant potential for functional foods aimed at enhancing fatty acid bioavailability.
- Films of chitosan and natural modified hydroxyapatite as effective UV-protecting, biocompatible and antibacterial wound dressingsPublication . Cunha, Carla S.; Castro, Pedro J.; Sousa, Sérgio C.; Pullar, Robert C.; Tobaldi, David M.; Piccirillo, Clara; Pintado, Maria M.Chitosan is a natural polysaccharide widely used in biomedicine, for instance for wound dressing. Hydroxyapatite is a very bioactive calcium phosphate which, if modified with an appropriate element (iron Fe), can also have UV-absorbing properties. In this work, we report the study of films of chitosan incorporated with iron-modified hydroxyapatite of natural origin (from cod fish bones); this combination led to an innovative chitosan-based material with excellent and advanced functional properties. The films showed very high UV absorption (Ultraviolet Protection Factor (UPF) value higher than 50). This is the first time that a chitosan-based material has shown such high UV protection properties. The films also showed to be non-cytotoxic, and possessed antimicrobial activity towards both Gram-positive and negative strains. Their mechanical properties, optimised with an experimental design approach, confirmed their potential use as multifunctional wound dressing, capable of reducing bacterial infections and, at the same time, protecting from UV light.
- Microencapsulation of Lactobacillus paracasei LAFTI® L26 by extrusion in an alginate matrixPublication . Sousa, Sérgio C.; Gomes, Ana M.; Pintado, Maria M.; Malcata, F. Xavier; Rodrigues, Dina; Rocha-Santos, Teresa; Silva, José P.; Lobo, José M. Sousa; Costa, Paulo; Amaral, Maria H.; Bahia, Maria F.; Freitas, Ana C.Probiotic bacteria are currently used in the development of functional food products, yet sometimes face technological challenges when incorporated in food matrices with more aggressive environments – salt, acid or oxygen concentrations. Encapsulation is an efficient technique to overcome such difficulties since encapsulation microcapsules help in their protection from both the product intrinsic properties and the gastrointestinal tract. Among the many factors influencing encapsulation efficiency, capsule size is an important issue since it can affect the textural and sensorial properties of the food product to which they are added. In this research work the microencapsulation efficiency and stability throughout storage of calcium alginate capsules (produced by extrusion) of Lactobacillus paracasei LAFTI® L26 was studied. Initially, extrusion by coaxial flow was used for encapsulation. Storage in Ringer solution at 4 ºC in a 1:9 (g/mL) racio – and the effect of a protecting agent – lactose, were assessed (samples collected at 0, 3, 5, 7 and 14d). In order to reduce the capsules’ size, extrusion by aerodynamically assisted flow was also tested and two different rupture solutions (sodium citrate 2 %(w/v) and phosphate buffer (0.5 M; pH 7)) were assessed. The capsules obtained via extrusion by coaxial flow presented dimensions superior to 200 µm. The incorporation method was shown to be effective. Suspension of the L. paracasei LAFTI® L26 alginate capsules in Ringer solution and storage at 4 ºC was shown to be a good preservation method and lactose did not present a protective effect. Such encapsulation increased survival of bacteria under storage at 4 ºC for two months (samples collected at 0, 3, 5, 7, 14, 21, 30 and 60d), reducing the decline of viable cell numbers when in comparison with free cells (3 log cycles versus 4 log cycles). The size of the capsules obtained using extrusion by aerodynamically assisted flow was smaller than 100 µm which allows the capsules to be incorporated in food products without a negative sensorial perception. The encapsulation method was also shown to be effective and no difference between rupture solutions was observed.
- Modification of acorn starch structure and properties by high hydrostatic pressurePublication . Castro, Luís M. G.; Caço, Ana I.; Pereira, Carla F.; Sousa, Sérgio C.; Brassesco, María E.; Machado, Manuela; Ramos, Óscar L.; Alexandre, Elisabete M. C.; Saraiva, Jorge A.; Pintado, ManuelaDespite being rich in starch, over half of acorn production is undervalued. High hydrostatic pressure was used to modify the properties of Q. pyrenaica (0.1 and 460 MPa for 20 min) and Q. robur (0.1 and 333 MPa for 17.4 min) acorn starches to obtain high-valued ingredients. Pressure significantly altered the span distribution and heterogeneity of the acorn starch granules depending on the species, but their morphology was unaffected. Pressurization increased the amylose/amylopectin ratio and damaged starch contents, but the effect was more prominent in Q. pyrenaica than in Q. robur. However, the polymorphism, relative crystallinity, gelatinization temperatures, and enthalpies were preserved. The pressure effect on the starch properties depended on the property and species. The solubility, swelling power, and acorn gels’ resistance towards deformation for both species decreased after pressurization. For Q. pyrenaica starch, the in vitro digestibility increased, but the pseudoplastic behavior decreased after pressurization. No differences were seen for Q. robur. Regarding the commercial starch, acorn starches had lower gelatinization temperatures and enthalpies, lower in vitro digestibility, lower resistance towards deformation, superior pseudoplastic behavior, and overall higher solubility and swelling power until 80 °C. This encourages the usage of acorn starches as a new food ingredient.
- Modification of acorn starch structure and properties by high hydrostatic pressurePublication . Castro, Luís M. G.; Caço, Ana I.; Pereira, Carla F.; Sousa, Sérgio C.; Brassesco, María E.; Machado, Manuela; Ramos, Óscar L.; Alexandre, Elisabete M. C.; Saraiva, Jorge A.; Pintado, ManuelaDespite being rich in starch, over half of acorn production is undervalued. High hydrostatic pressure was used to modify the properties of Q. pyrenaica (0.1 and 460 MPa for 20 min) and Q. robur (0.1 and 333 MPa for 17.4 min) acorn starches to obtain high-valued ingredients. Pressure significantly altered the span distribution and heterogeneity of the acorn starch granules depending on the species, but their morphology was unaffected. Pressurization increased the amylose/amylopectin ratio and damaged starch contents, but the effect was more prominent in Q. pyrenaica than in Q. robur. However, the polymorphism, relative crystallinity, gelatinization temperatures, and enthalpies were preserved. The pressure effect on the starch properties depended on the property and species. The solubility, swelling power, and acorn gels’ resistance towards deformation for both species decreased after pressurization. For Q. pyrenaica starch, the in vitro digestibility increased, but the pseudoplastic behavior decreased after pressurization. No differences were seen for Q. robur. Regarding the commercial starch, acorn starches had lower gelatinization temperatures and enthalpies, lower in vitro digestibility, lower resistance towards deformation, superior pseudoplastic behavior, and overall higher solubility and swelling power until 80 ?C. This encourages the usage of acorn starches as a new food ingredient.
- Obtention and characterization of microcrystalline cellulose from industrial melon residues following a biorefinery approachPublication . Gómez-García, Ricardo; Sousa, Sérgio C.; Ramos, Óscar L.; Campos, Débora A.; Aguilar, Cristóbal N.; Madureira, Ana R.; Pintado, ManuelaResidual melon by-products were explored for the first time as a bioresource of microcrystalline cellulose (MCC) obtention. Two alkaline extraction methods were employed, the traditional (4.5% NaOH, 2 h, 80 °C) and a thermo-alkaline in the autoclave (2% NaOH, 1 h, 100 °C), obtaining a yield of MCC ranging from 4.76 to 9.15% and 2.32 to 3.29%, respectively. The final MCCs were characterized for their chemical groups by Fourier-transform infrared spectroscopy (FTIR), crystallinity with X-ray diffraction, and morphology analyzed by scanning electron microscope (SEM). FTIR spectra showed that the traditional protocol allows for a more effective hemicellulose and lignin removal from the melon residues than the thermo-alkaline process. The degree of crystallinity of MCC ranged from 51.51 to 61.94% and 54.80 to 55.07% for the thermo-alkaline and traditional processes, respectively. The peaks detected in X-ray diffraction patterns indicated the presence of Type I cellulose. SEM analysis revealed microcrystals with rough surfaces and great porosity, which could remark their high-water absorption capacity and drug-carrier capacities. Thus, these findings could respond to the need to valorize industrial melon by-products as raw materials for MCC obtention with potential applications as biodegradable materials.
- Silica microparticles from sugarcane by-products as an encapsulation system for retinoids aimed at topical sustained releasePublication . Costa, Joana R.; Costa, Ana Helena; Azevedo-Silva, João; Tavares-Valente, Diana; Sousa, Sérgio C.; Neto, Tânia; Pintado, Manuela E.; Madureira, Ana RaquelThe encapsulation of retinol within silica microparticles has emerged as a promising opportunity in the realm of cosmetic and pharmaceutical formulations, driven by the need to reinforce the photoprotection and oxidation stability of retinol. This work examines the process of encapsulating retinol into silica microparticles. The association efficiency, microparticle size, molecular structure, morphology, oxidation, and release profile, as well as biocompatibility and skin sensitization, were evaluated. Results showed that 0.03% of retinol and 9% of emulsifier leads to an association efficiency higher than 99% and a particle size with an average of 5.2 µm. FTIR results indicate that there is an association of retinol with the silica microparticles, and some may be on the surface. Microscopy indicates that when association happens, there is less aggregation of the particles. Oxidation occurs in two different phases, the first related to the retinol on the surface and the second to the associated retinol. In addition, a burst release of up to 3 h (30% free retinol, 17% associated retinol) was observed, as well as a sustained release of 44% of retinol up to 24 h. Encapsulation allowed an increase in the minimal skin cytotoxic concentrations of retinol from 0.04 μg/mL to 1.25 mg/mL without skin sensitization. Overall, retinol is protected when associated with silica microparticles, being safe to use in cosmetics and dermatology.