Polysaccharides, Volume 4, Issue 2 (June 2023) – 7 articles

Xylan is a macromolecule of industrial interest that can be solubilized from lignocellulosic materials, such as sugarcane bagasse, which is a renewable source. However, the solubilization methods of xylan need to be better developed for use in industrial applications. The main objective of this study was to evaluate xylan solubilization methods with higher yields and purity by using biomasses/fractions of sugarcane: leaf and stem, internode, node, and external fraction. Two strategies were evaluated by applying diluted sodium chlorite, sodium sulfite, and hydrogen peroxide: a delignification of the biomass before xylan solubilization; and the delignification of the solubilized xylan for residual lignin removal. The delignification of the biomass before the xylan solubilization enabled to identify material and specific conditions for yields higher than 90%. Residual lignin varied from 3.14 to 18.06%, with hydrogen peroxide in alkaline medium partial delignification shown to be effective. The delignification of xylan presented better results using diluted hydrogen peroxide, with a reduction of 58.44% of the initial lignin content. The solubilized xylans were used as a substrate for xylanase activities, resulting in higher activity than commercial xylan. In the delignification of the biomasses, hydrogen peroxide was the reagent with better results concerning the yield, purity, and solubility of the xylan. This reagent (diluted) was also better in the delignification of the solubilized xylan, resulting in lower residual lignin content. The solubility and purity tests (low salt content) indicated that the solubilized xylan presented characteristics that were similar to or even better than commercial xylan. Full article

The elevation of carbon dioxide (CO₂) levels in the atmosphere is responsible for global warming which in turn causes abrupt climate change and consequently poses a threat to living organisms in the coming years. To reduce CO₂ content in the atmosphere CO₂ capture and separation is highly necessary. Among various methods of CO₂ capture post-combustion capture is very much useful because of its operational simplicity and applicability in many industries and power sectors, such as coal-fired power plants. Polymers with high surface area, high volume and narrow pores are ideal solid sorbents for adsorption-driven post-combustion CO₂ capture. Natural polymers, such as polysaccharides are cheap, abundant, and can be modified by various methods to produce porous materials and thus can be effectively utilized for CO₂ capture while the surface area and the pore size of synthetic porous organic polymers can be tuned precisely for high CO₂ capturing capacity. A significant amount of research activities has already been established in this field, especially in the last ten years and are still in progress. In this review, we have introduced the latest developments to the readers about synthetic techniques, post-synthetic modifications and CO₂ capture capacities of various biopolymer-based materials and synthetic porous organic polymers (POPs) published in the last five years (2018–2022). This review will be beneficial to the researchers to design smart polymer-based materials to overcome the existing challenges in carbon capture and storage/sequestration. Full article

IgE-mediated allergic reaction occurs in response to harmless environmental compounds, such as tree and grass pollen, fragments of household microorganisms, etc. To date, the only way to treat IgE-mediated allergy is allergen-specific immunotherapy (ASIT), which consists of a prolonged subcutaneous administration of allergen extracts or recombinant proteins. The long duration of the treatment, the cost and the risk of life-threatening adverse reactions are the main limiting factors for ASIT. The aim of this work was to develop allergen proteins encapsulated in chitosan-based microparticles that can be safely administered at high doses and in a rash protocol. The egg white allergen, Gal d 1 protein, was used as a model antigen. The protein was packed into core–shell type microparticles (MPs), in which the core was formed with succinyl chitosan conjugated to Gal d 1, subsequently coated with a shell formed by quaternized chitosan. The obtained core–shell MPs containing Gal d 1 in the core (Gal-MPs) were non-toxic to macrophage and fibroblast cell lines. At the same time, Gal-MPs were quickly engulfed by bone marrow-derived dendritic cells or RAW264.7 macrophage cells, as was visualized using flow cytometry and confocal microscopy. Encapsulated Gal d 1 was not recognized by Gal d 1-specific IgE in ELISA. Female BALB/c mice were immunized with Gal-MPs subcutaneously three times a week for 2 weeks. Immunization of mice resulted in IgG titers 1250 ± 200 without IgE production. Allergy in control and vaccinated mice was induced by low-dose Gal d 1 injections in the withers of mice. IgE was induced in control-sensitized but not in the vaccinated mice. Thus, preventive vaccination with the encapsulated allergens is safe and rapid; it significantly reduces the risk of IgE production induced by respiratory and oral allergens. Full article

Nanoparticle-based seed priming has opened new avenues in crop science due to their plant growth promoting potential. Similarly, biopolymers such as chitosan (CS) are widely studied as seed priming agents due to the biodegradable and biocompatible nature, ability to enhance germination percentage and overall seedling health. Therefore, priming with chitosan nanoparticles (CNPs) is a promising tool to enhance overall plant health. Here, we studied the effect of nanopriming with CNPs or CS (50 µg/mL) on morphological, physiological, and biochemical parameters of rice seedlings, grown in salinity stress conditions NaCl (0–250 mM). CNPs were synthesized using an ionic gelation method and characterized by scanning electron microscopy (50–100 nm), zeta potential analyser (Particle size distribution–373.5 ± 3.7 nm; polydispersity index- > 0.4; zeta potential–45.3 ± 2.5 mV) and profilometry (300–1500 nm hydrodynamic height). Morphological, physiological, and biochemical responses of rice seedlings grown from seeds primed with either CNPs or CS showed a positive effect on germination, seedling vigour, biochemical and antioxidant responses. Seeds primed with CNPs and CS demonstrated significantly higher germination potential and seedling vigour compared to control hydro-primed seeds when grown under increasing NaCl concentrations. These outcomes highlight that CNPs and CS can be used as potential seed priming agents to alleviate salinity stress in rice seedlings. However, further studies are warranted to understand the effect of CNPs and CS seed priming on the overall growth and development of rice plants as well as rice yield. Full article

The consumption of insects as an alternative protein source is acceptable as a sustainable alternative to mainstream protein sources. Apart from containing a high protein content, insects also have dietary fiber in the form of chitin, which helps to enrich gut microbiota. The importance of the gut microbiome in general health has recently been underlined for humans, farm animals, pets, poultry, and fish. The advances in 16S RNA techniques have enabled the examination of complex microbial communities in the gastrointestinal tract, shedding more light on the role of diet in disease and immunity. The gut microbiome generates signals influencing the normal nutritional status, immune functions, metabolism, disease, and well-being. The gut microbiome depends on dietary fiber; hence, their diversity is modulated by diet, a relevant factor in defining the composition of gut microbiota. Small shifts in diet have demonstrated an enormous shift in gut microbiota. Edible insects are an excellent source of protein, fat, and chitin that could influence the gut microbiota as a prebiotic. Chitin from insects, when consumed, contributes to a healthy gut microbiome by increasing diversity in fecal microbiota. Moreover, a high fiber intake has been associated with a reduced risk of breast cancer, diverticular disease, coronary heart disease, and metabolic syndrome. This review presents edible insects with a focus on fiber found in the insect as a beneficial food component. Full article

Most foods derived from plant origin are very nutritious but highly perishable products. Nowadays, the food industry is focusing on the development of efficient preservation strategies as viable alternatives to traditional packaging and chemical treatments. Hence, polysaccharide-based edible coatings have been proposed because of their properties of controlled release of food additives and the protection of sensitive compounds in coated foods. Thus, this technology has allowed for improving the quality parameters and extends the shelf life of fruits and vegetables through positive effects on enzyme activities, physicochemical characteristics (e.g., color, pH, firmness, weight, soluble solids), microbial load, and nutritional and sensory properties of coated foods. Additionally, some bioactive compounds have been incorporated into polysaccharide-based edible coatings, showing remarkable antioxidant and antimicrobial properties. Thus, polysaccharide-based edible coatings incorporated with bioactive compounds can be used not only as an efficient preservation strategy but also may play a vital role in human health when consumed with the food. The main objective of this review is to provide a comprehensive overview of materials commonly used in the preparation of polysaccharide-based edible coatings, including the main bioactive compounds that can be incorporated into edible coatings, which have shown specific bioactivities. Full article

This work evaluated the hydrodynamic properties of heparin hydrolysed at temperatures ranging from 40 °C to 80 °C in buffered acid and alkaline environments. The correlation between hydrodynamic parameters led to the conclusion that polymer conformational changes appeared to be minimal until chain depolymerisation, initiated at pH 1 and 80 °C. However, the synergy of conformational changes, even if minimal, and sulphate loss observed at pH 1, pH 3 and pH 12 (various temperatures) resulted in a loss of the antifactor Xa activity. Therefore, the ‘contribution’ of conformational changes should be added to the generally recognized effect of desulphation towards the activity of heparin. This is of significance as the processing of medical heparin is complex, and requires adjustment of several physical and chemical factors, including pH and temperature. Full article