Browsing by Author "Freixo, Ricardo"
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- Bio-based superabsorbent hydrogels for nutrient releasePublication . Ribeiro, Alessandra B.; Moreira, Helena; Pereira, Sofia I. A.; Godinho, Mariana; Sousa, Ana Sofia da Silva; Castro, Paula; Pereira, Carla F.; Casanova, Francisca; Freixo, Ricardo; Pintado, Manuela E.; Ramos, Óscar L.Drought is characterized by a low water precipitation rate, with strong impact on crop productivity, threatening global food production. In this context, the use of soil amendments, such as superabsorbent hydrogels constitute a potential technology for better water use efficiency and higher crop yields. In this work, we synthesised cellulose-based hydrogels, characterized their physical and functional properties, evaluated their impact on the environment, and their potential to be used as a soil amendments. The hydrogel showed pH of 6.0 to 7.5 and conductivity below 10.0 µS cm-1. The Fourier-transform infrared spectroscopy (FTIR) showed a low intensity peak in the crystallinity region, which was supported by the low crystallinity index (27.3% ± 0.6) verified by Powder X-ray diffraction (PXRD) analysis. The swelling capacity reached more than 200 g of water, the hydrogel showed good resistance to osmotic pressure and high thermostability, which favours the application in hot and arid areas. In addition, no potentially hazardous compound was detected, nor was there any adverse effect on soil microorganisms. Further, the hydrogel was found to be safe for use during seed sowing and for promoting seedling development. In the greenhouse pot experiment, the hydrogels showed a significant increase in maize shoot and root biomass, demonstrating their ability to contribute to the overall water holding capacity of the soil, thereby influencing nutrient availability for more efficient plant growth. In conclusion, the superabsorbent hydrogel exhibited promising characteristics for use as a soil amendment, scalability potential and constitutes a sustainable alternative for agricultural applications.
- Bio-based superabsorbent hydrogels for nutrient-controlled releasePublication . Ribeiro, Alessandra B.; Moreira, Helena; Pereira, Sofia I. A.; Godinho, Mariana; Castro, Paula; Pereira, Carla F.; Casanova, Francisca; Freixo, Ricardo; Pintado, Manuela E.; Ramos, Óscar L.The drought is characterized by a low water precipitation rate, with strong impact on the crop productivity, threaten global food production. In this context, the use of soil amendments, such as superabsorbent hydrogels constitute a potential technology for water use efficiency and increase crop yields. In this work, it was synthesised a cellulose-based hydrogel, carrying out its characterisation, evaluated its environmental safety and its potential to be used as a soil amendment. The hydrogel was successfully synthesised using a simple process and inexpensive reagents. The hydrogel showed pH of 6.0 to 7.5 and conductivity below 10.0 µS cm-1. The FTIR showed a low intensity peak in the crystallinity region, which was supported by the low crystallinity index (27.3 % ± 0.6) verified by PXRD analysis. The swelling capacity reached more than 200 g of water, the hydrogel showed good resistance to osmotic pressure and high thermostability, which favours the application in hot and arid areas. Regarding the safety evaluation, no potentially hazardous compound was detected, nor was there any adverse effect on soil microrganisms. In addition, the hydrogel was found to be safe for use during sowing and for promoting seedling development. In the green pot experiment, the hydrogel demonstrated a significant increase in maize biomass, root biomass and potential to serve as a reservoir for soil nutrients. In conclusion, the superabsorbent hydrogel exhibited promising characteristics for use as a soil amendment, scalability potential and constitutes a sustainable alternative for agricultural applications.
- Biological potential and bioaccessibility of encapsulated curcumin into cetyltrimethylammonium bromide modified cellulose nanocrystalsPublication . Casanova, Francisca; Pereira, Carla F.; Ribeiro, Alessandra B.; Castro, Pedro M.; Freixo, Ricardo; Martins, Eva; Tavares-Valente, Diana; Fernandes, João C.; Pintado, Manuela E.; Ramos, Óscar L.Curcumin is a natural phenolic compound with important biological functions. Despite its demonstrated efficacy in vitro, curcumin biological activities in vivo are dependent on its bioaccessibility and bioavailability, which have been highlighted as a crucial challenge. Cetyltrimethylammonium bromide-modified cellulose nanocrystals (CNC-CTAB) have been shown to be effective in curcumin encapsulation, as they have the potential to enhance biological outcomes. This study evaluated the biological effects of curcumin encapsulated within CNC-CTAB structures, namely its antioxidant, anti-inflammatory and antimicrobial properties, as well as the release profile under digestion conditions and intestinal permeability. Encapsulated curcumin demonstrated antioxidant and anti-inflammatory properties, effectively reducing reactive oxygen species and cytokine production by intestinal cells. The delivery system exhibited antimicrobial properties against Campylobacter jejuni bacteria, further suggesting its potential in mitigating intestinal inflammation. The system showed the ability to protect curcumin from degradation and facilitate its interaction with the intestinal epithelium, highlighting the potential of CNC-CTAB as carrier to enhance curcumin intestinal biological functions.
- Carboxymethyl cellulose as a food emulsifier: are its days numbered?Publication . Costa, Eduardo M.; Silva, Sara; Pereira, Carla F.; Ribeiro, Alessandra B.; Casanova, Francisca; Freixo, Ricardo; Pintado, Manuela; Ramos, Óscar L.Carboxymethyl cellulose use in industry is ubiquitous. Though it is recognized as safe by the EFSA and FDA, newer works have raised concerns related to its safety, as in vivo studies showed evidence of gut dysbiosis associated with CMC’s presence. Herein lies the question, is CMC a gut pro-inflammatory compound? As no work addressed this question, we sought to understand whether CMC was pro-inflammatory through the immunomodulation of GI tract epithelial cells. The results showed that while CMC was not cytotoxic up to 25 mg/mL towards Caco-2, HT29-MTX and Hep G2 cells, it had an overall pro-inflammatory behavior. In a Caco-2 monolayer, CMC by itself increased IL-6, IL-8 and TNF-α secretion, with the latter increasing by 1924%, and with these increases being 9.7 times superior to the one obtained for the IL-1β pro-inflammation control. In co-culture models, an increase in secretion in the apical side, particularly for IL-6 (692% increase), was observed, and when RAW 264.7 was added, data showed a more complex scenario as stimulation of pro-inflammatory (IL-6, MCP-1 and TNF-α) and anti-inflammatory (IL-10 and IFN-β) cytokines in the basal side was observed. Considering these results, CMC may exert a pro-inflammatory effect in the intestinal lumen, and despite more studies being required, the incorporation of CMC in foodstuffs must be carefully considered in the future to minimize potential GI tract dysbiosis.
- Cello-oligosaccharides from sugarcane bagasse and their emerging potential as prebiotic agentsPublication . Freixo, Ricardo; Ribeiro, Alessandra B.; Costa, Eduardo M.; Bastos, Francisca; Pereira, Carla F.; Pintado, Manuela E.; Ramos, Óscar L.
- Cellulose from sugarcane bagasse as a potential prebiotic agentPublication . Freixo, Ricardo; Bastos, Francisca; Costa, Eduardo; Ribeiro, Alessandra B.; Pereira, Carla F.; Pintado, Manuela E.; Ramos, Oscar L.
- Cellulose from sugarcane bagasse as a potential prebiotic agentPublication . Freixo, Ricardo; Casanova, Francisca; Costa, Eduardo; Ribeiro, Alessandra B.; Pereira, Carla F.; Pintado, Manuela E.; Ramos, Óscar L.Organic farming practices have been slowly replacing intensive agriculture with the use of plant growth promoting bacteria as key factor, as these bacteria interact effectively with plants and increase crop yields. However, despite the potential of bioinoculants, its usage in agriculture is still limited as their efficacy also depends upon other abiotic factors such as the soil type and its nutrients. A novel approach to bypass this limitation is the introduction of prebiotic agents to increase the richness of the soil and thus promote bacterial growth (Arif et., al 2020). Among the possible alternatives for soil supplementation, cellulose constitutes one of the best choices, as it is a renewable carbon source, widely abundant in nature and for which a great number of microorganisms produce enzymes. The aim of this work is to evaluate the prebiotic potential of cellulose, extracted from sugarcane bagasse, as prebiotic agent. To that end, cellulose was firstly extracted from sugarcane bagasse through an optimized procedure comprising an alkaline extraction with sodium hydroxide followed by a bleaching process with hydrogen peroxide. The capacity to promote the growth (prebiotic effect) of three soil representative microorganisms and nitrogen fixators i.e., Rhodococcus sp. EC35, Pseudomonas azotoformans and Chryseobacterium humi was evaluated for two cellulose extracts (i.e., raw cellulose and cellulose pulp) obtained from sugarcane bagasse. The results showed that the extraction process yielded ca. 63% and 42% for raw cellulose and cellulose pulp, respectively, being both extracts effective as prebiotic agents for the target microorganisms. Growth rates of 38 and 68% for Rhodococcus sp., and of 67 and 84% for C. humi was found for cellulose pulp and raw cellulose, respectively. On the other hand, for P. azotoformans, raw cellulose had no impact upon the growth rate, while cellulose pulp lead to a small decrease (ca. 7%). When comparing this data with the obtained for a standard cellulose from Sigma, it was possible to observe that the commercial cellulose was, in general, less effective as an environmental prebiotic as it only exhibited significant effects in the growth of C. humi. These results showed the potential of sugarcane bagasse as source of a natural bioinocula with prebiotic effect, thus potentiating the valorization of an industrial byproduct with low commercial value into a product with biological effect on soils supplementation.
- Characterization and evaluation of commercial carboxymethyl cellulose potential as an active ingredient for cosmeticsPublication . Costa, Eduardo M.; Pereira, Carla F.; Ribeiro, Alessandra A.; Casanova, Francisca; Freixo, Ricardo; Pintado, Manuela; Ramos, Óscar L.Carboxymethyl cellulose is the most used water-soluble cellulose with applications in industries such as food, cosmetics, and tissue engineering. However, due to a perceived lack of biological activity, carboxymethyl cellulose is mostly used as a structural element. As such, this work sought to investigate whether CMC possesses relevant biological properties that could grant it added value as a cosmeceutical ingredient in future skincare formulations. To that end, CMC samples (Mw between 471 and 322 kDa) skin cell cytotoxicity, impact upon pro-collagen I α I production, and inflammatory response were evaluated. Results showed that samples were not cytotoxic towards HaCat and HDFa up to 10 mg/mL while simultaneously promoting intracellular production of pro-collagen I α I up by 228% relative to the basal metabolism, which appeared to be related to the highest DS and Mw. Additionally, CMC samples modulated HaCat immune response as they decreased by ca. 1.4-fold IL-8 production and increased IL-6 levels by ca. five fold. Despite this increase, only two samples presented IL-6 levels similar to those of the inflammation control. Considering these results, CMC showed potential to be a more natural alternative to traditional bioactive cosmetic ingredients and, as it is capable of being a bioactive and structural ingredient, it may play a key role in future skincare formulations.
- Comparative study of green and traditional routes for cellulose extraction from a sugarcane by-productPublication . Casanova, Francisca; Freixo, Ricardo; Pereira, Carla F.; Ribeiro, Alessandra B.; Costa, Eduardo M.; Pintado, Manuela E.; Ramos, Óscar L.Sugarcane bagasse (SCB) is the main residue of the sugarcane industry and a promising renewable and sustainable lignocellulosic material. The cellulose component of SCB, present at 40–50%, can be used to produce value-added products for various applications. Herein, we present a comprehensive and comparative study of green and traditional approaches for cellulose extraction from the by-product SCB. Green methods of extraction (deep eutectic solvents, organosolv, and hydrothermal processing) were compared to traditional methods (acid and alkaline hydrolyses). The impact of the treatments was evaluated by considering the extract yield, chemical profile, and structural properties. In addition, an evaluation of the sustainability aspects of the most promising cellulose extraction methods was performed. Among the proposed methods, autohydrolysis was the most promising approach in cellulose extraction, yielding 63.5% of a solid fraction with ca. 70% cellulose. The solid fraction showed a crystallinity index of 60.4% and typical cellulose functional groups. This approach was demonstrated to be environmentally friendly, as indicated by the green metrics assessed (E(nvironmental)-factor = 0.30 and Process Mass Intensity (PMI) = 20.5). Autohydrolysis was shown to be the most cost-effective and sustainable approach for the extraction of a cellulose-rich extract from SCB, which is extremely relevant for aiming the valorization of the most abundant by-product of the sugarcane industry.
- Design of cellulose based micro and nanostructures for encapsulation and release of curcuminPublication . Casanova, Francisca; Pereira, Carla F.; Ribeiro, Alessandra B.; Freixo, Ricardo; Costa, Eduardo; Pintado, Manuela E.; Fernandes, João; Ramos, Óscar L.
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