Natural Polysaccharide-Based Hydrogels Used for Dye Removal

Removal of contaminants from discharge water is vital and demands urgent assistance with the goal to keep clean water. Adsorption is one of the most common, efficient, and low-priced methods used in water treatment. Various polysaccharide-based gels have been used as efficient dye adsorbents from wastewater. This review summarizes cutting-edge research of the last decade of different hydrogels based on natural polysaccharides (chitin, chitosan, cellulose, starch, pullulan, and dextran) concerning their dye adsorption efficiency. Beyond their natural abundance, attributes of polysaccharides such as biocompatibility, biodegradability, and low cost make them not only efficient, but also environmentally sustainable candidates for water purification. The synthesis and dye removal performance together with the effect of diverse factors on gels retaining ability, kinetic, and isotherm models encountered in adsorption studies, are introduced. Thermodynamic parameters, sorbent recycling capacity along with conclusions and future prospects are also presented.

Facile Synthesis of Ni-Doped ZnO Nanoparticles Using Cashew Gum: Investigation of the Structural, Optical, and Photocatalytic Properties

This work adopted a green synthesis route using cashew tree gum as a mediating agent to obtain Ni-doped ZnO nanoparticles through the sol-gel method. Structural analysis confirmed the formation of the hexagonal wurtzite phase and distortions in the crystal lattice due to the inclusion of Ni cations, which increased the average crystallite size from 61.9 nm to 81.6 nm. These distortions resulted in the growth of point defects in the structure, which influenced the samples' optical properties, causing slight reductions in the band gaps and significant increases in the Urbach energy. The fitting of the photoluminescence spectra confirmed an increase in the concentration of zinc vacancy defects (VZn) and monovacancies (Vo) as Zn cations were replaced by Ni cations in the ZnO structure. The percentage of VZn defects for the pure compound was 11%, increasing to 40% and 47% for the samples doped with 1% and 3% of Ni cations, respectively. In contrast, the highest percentage of VO defects is recorded for the material with the lowest Ni ions concentration, comprising about 60%. The influence of dopant concentration was also reflected in the photocatalytic performance. Among the samples tested, the Zn0.99Ni0.01O compound presented the best result in MB degradation, reaching an efficiency of 98.4%. Thus, the recovered material underwent reuse tests, revealing an efficiency of 98.2% in dye degradation, confirming the stability of the photocatalyst. Furthermore, the use of different inhibitors indicated that •OH radicals are the main ones involved in removing the pollutant. This work is valuable because it presents an ecological synthesis using cashew gum, a natural polysaccharide that has been little explored in the literature.

Utilization of Food-Derived β-Glucans to Prevent and Treat Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease nowadays. Currently, there is no officially approved drug to treat NAFLD. In view of the increasing global prevalence of NAFLD and an absence of treatments, the development of effective treatments is of utmost importance. β-glucan, a natural bioactive polysaccharide, has demonstrated hepatoprotective effects in NAFLD prevention and treatment. This review solely focuses on gathering the published preclinical animal studies that demonstrated the anti-liver injury, anti-steatotic, anti-inflammatory, anti-fibrotic, and antioxidant activities of β-glucan. The impact of β-glucan on gut microbiota and its metabolites including short-chain fatty acids and bile acids as the underlying mechanism for its bioactive beneficial effect on NAFLD is also explored. Given the limited knowledge of β-glucan on anti-fibrotic activity, bile acid metabolism, and gut microbiota function, additional relevant research is highly encouraged to lay a solid foundation for the use of food-derived β-glucan as a functional food for NAFLD. It is envisaged that further investigation of food-derived β-glucan in human clinical studies should be carried out for its wider utilization.

Application of chromatography in purification and structural analysis of natural polysaccharides: A review

Polysaccharides are widely distributed in natural sources from monocytic microorganisms to higher animals, and are found in a variety of biological activities in recent decades. Natural polysaccharides have the characteristics of large molecular weight, diverse composition, and complex structure, so their purification and structural analysis are difficult issues in research. Chromatography as a powerful separation technique, plays an irreplaceable role in the separation and structural analysis of natural polysaccharides, especially in the purification of polysaccharides, the separation of hydrolysates, and the analysis of monosaccharide composition. The separation mechanisms and application of different chromatographic methods in the studies of polysaccharides were summarized in this review. Moreover, the advantages and drawbacks of various chromatography methods were discussed as well.

Microbiota-sensitive drug delivery systems based on natural polysaccharides for colon targeting

Colon targeting is an ongoing challenge, particularly for the oral administration of biological drugs or local treatment of inflammatory bowel disease (IBD). In both cases, drugs are known to be sensitive to the harsh conditions of the upper gastrointestinal tract (GIT) and, thus, must be protected. Here, we provide an overview of recently developed colonic site-specific drug delivery systems based on microbiota sensitivity of natural polysaccharides. Polysaccharides act as a substrate for enzymes secreted by the microbiota located in the distal part of GIT. The dosage form is adapted to the pathophysiology of the patient and, thus, a combination of bacteria-sensitive and time-controlled release or pH-dependent systems can be used for delivery.

Advances in health-promoting effects of natural polysaccharides: Regulation on Nrf2 antioxidant pathway

Natural polysaccharides (NPs) possess numerous health-promoting effects, such as liver protection, kidney protection, lung protection, neuroprotection, cardioprotection, gastrointestinal protection, anti-oxidation, anti-diabetic, and anti-aging. Nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway is an important endogenous antioxidant pathway, which plays crucial roles in maintaining human health as its protection against oxidative stress. Accumulating evidence suggested that Nrf2 antioxidant pathway might be one of key regulatory targets for the health-promoting effects of NPs. However, the information concerning regulation of NPs on Nrf2 antioxidant pathway is scattered, and NPs show different regulatory behaviors in their different health-promoting processes. Therefore, in this article, structural features of NPs having regulation on Nrf2 antioxidant pathway are overviewed. Moreover, regulatory effects of NPs on this pathway for health-promoting effects are summarized. Furthermore, structure-activity relationship of NPs for health-promoting effects by regulating the pathway is preliminarily discussed. Otherwise, the prospects on future work for regulation of NPs on this pathway are proposed. This review is beneficial to well-understanding of underlying mechanisms for health-promoting effects of NPs from the view angle of Nrf2 antioxidant pathway, and provides a theoretical basis for the development and utilization of NPs in promoting human health.

Antioxidant Activities of Natural Polysaccharides and Their Derivatives for Biomedical and Medicinal Applications

Many chronic diseases such as Alzheimer's disease, diabetes, and cardiovascular diseases are closely related to in vivo oxidative stress caused by excessive reactive oxygen species (ROS). Natural polysaccharides, as a kind of biomacromolecule with good biocompatibility, have been widely used in biomedical and medicinal applications due to their superior antioxidant properties. In this review, scientometric analysis of the highly cited papers in the Web of Science (WOS) database finds that antioxidant activity is the most widely studied and popular among pharmacological effects of natural polysaccharides. The antioxidant mechanisms of natural polysaccharides mainly contain the regulation of signal transduction pathways, the activation of enzymes, and the scavenging of free radicals. We continuously discuss the antioxidant activities of natural polysaccharides and their derivatives. At the same time, we summarize their applications in the field of pharmaceutics/drug delivery, tissue engineering, and antimicrobial food additives/packaging materials. Overall, this review provides up-to-date information for the further development and application of natural polysaccharides with antioxidant activities.

Natural Polysaccharide-Based Nanodrug Delivery Systems for Treatment of Diabetes

In recent years, natural polysaccharides have been considered as the ideal candidates for novel drug delivery systems because of their good biocompatibility, biodegradation, low immunogenicity, renewable source and easy modification. These natural polymers are widely used in the designing of nanocarriers, which possess wide applications in therapeutics, diagnostics, delivery and protection of bioactive compounds or drugs. A great deal of studies could be focused on developing polysaccharide nanoparticles and promoting their application in various fields, especially in biomedicine. In this review, a variety of polysaccharide-based nanocarriers were introduced, including nanoliposomes, nanoparticles, nanomicelles, nanoemulsions and nanohydrogels, focusing on the latest research progress of these nanocarriers in the treatment of diabetes and the possible strategies for further study of polysaccharide nanocarriers.

Engineering Polysaccharide-Based Hydrogel Photonic Constructs: From Multiscale Detection to the Biofabrication of Living Optical Fibers

Solid-state optics has been the pillar of modern digital age. Integrating soft hydrogel materials with micro/nanooptics could expand the horizons of photonics for bioengineering. Here, wet-spun multilayer hydrogel fibers are engineered through ionic-crosslinked natural polysaccharides that serve as multifunctional platforms. The resulting flexible hydrogel structure and reversible crosslinking provide tunable design properties such as adjustable refractive index and fusion splicing. Modulation of the optical readout via physical stimuli, including shape, compression, and multiple optical inputs/outputs is demonstrated. The unique permeability of the hydrogels is also combined with plasmonic nanoparticles for molecular detection of SARS-CoV-2 in fiber-coupled biomedical swabs. A tricoaxial 3D printing nozzle is then employed for the continuous fabrication of living optical fibers. Light interaction with living cells enables the quantification and digitalization of complex biological phenomena such as 3D cancer progression and drug susceptibility. These fibers pave the way for advances in biomaterial-based photonics and biosensing platforms.

Novel Nanobiocomposites Based on Natural Polysaccharides as Universal Trophic Low-Dose Micronutrients

New promising manganese-containing nanobiocomposites (NCs) based on natural polysaccharides, arabinogalactan (AG), arabinogalactan sulfate (AGS), and κ-carrageenan (κ-CG) were studied to develop novel multi-purpose trophic low-dose organomineral fertilizers. The general toxicological effects of manganese (Mn) on the vegetation of potatoes (Solanum tuberosum L.) was evaluated in this study. The essential physicochemical properties of this trace element in plant tissues, such as its elemental analysis and its spectroscopic parameters in electron paramagnetic resonance (EPR), were determined. Potato plants grown in an NC-containing medium demonstrated better biometric parameters than in the control medium, and no Mn accumulated in plant tissues. In addition, the synthesized NCs demonstrated a pronounced antibacterial effect against the phytopathogenic bacterium Clavibacter sepedonicus (Cms) and were proved to be safe for natural soil microflora.

Natural Glycan Derived Biomaterials for Inflammation Targeted Drug Delivery

Inflammation is closely related to a variety of fatal or chronic diseases. Hence, targeting inflammation provides an alternative approach to improve the therapeutic outcome of diseases such as solid tumors, neurological diseases, and metabolic diseases. Polysaccharides are natural components with immune regulation, anti-virus, anti-cancer, anti-inflammation, and anti-oxidation activities. Herein, this review highlights recent progress in the polysaccharide-based drug delivery systems for achieving inflammation targeting and its related disease treatment. Moreover, the chemical modification and the construction of polysaccharide materials for drug delivery are discussed in detail.

Natural Polysaccharides and Their Derivates: A Promising Natural Adjuvant for Tumor Immunotherapy

The treatment process of tumor is advanced with the development of immunotherapy. In clinical experience, immunotherapy has achieved very significant results. However, the application of immunotherapy is limited by a variety of immune microenvironment. For a long time in the past, polysaccharides such as lentinan and Ganoderma lucidum glycopeptide have been used in clinic as adjuvant drugs to widely improve the immunity of the body. However, their mechanism in tumor immunotherapy has not been deeply discussed. Studies have shown that natural polysaccharides can stimulate innate immunity by activating upstream immune cells so as to regulate adaptive immune pathways such as T cells and improve the effect of immunotherapy, suggesting that polysaccharides also have a promising future in cancer therapy. This review systematically discusses that polysaccharides can directly or indirectly activate macrophages, dendritic cells, natural killer cells etc., binding to their surface receptors, inducing PI3K/Akt, mitogen-activated protein kinase, Notch and other pathways, promote their proliferation and differentiation, increasing the secretion of cytokines, and improve the state of immune suppression. These results provide relevant basis for guiding polysaccharide to be used as adjuvants of cancer immunotherapy.

Bone regeneration in both small and large preclinical bone defect models using an injectable polymer-based substitute containing hydroxyapatite and reconstituted with saline or autologous blood

Microbeads consisting of pullulan and dextran supplemented with hydroxyapatite have recently been developed for bone tissue engineering applications. Here, we evaluate the bone formation in two different preclinical models after injection of microbeads reconstituted with either saline buffer or autologous blood. Addition of saline solution or autologous blood to dried microbeads packaged into syringes allowed an easy injection. In the first rat bone defect model performed in the femoral condyle, microcomputed tomography performed after 30 and 60 days revealed an important mineralization process occurring around and within the core of the microbeads in both conditions. Bone volume/total volume measurements revealed no significant differences between the saline solution and the autologous blood groups. Histologically, osteoid tissue was evidenced around and in contact of the microbeads in both conditions. Using the sinus lift model performed in sheep, cone beam computed tomography revealed an important mineralization inside the sinus cavity for both groups after 3 months of implantation. Representative Masson trichrome staining images showed that bone formation occurs at the periphery and inside the microbeads in both conditions. Quantitative evaluation of the new bone formation displayed no significant differences between groups. In conclusion, reconstitution of microbeads with autologous blood did not enhance the regenerative capacity of these microbeads compared to the saline buffer group. This study is of particular interest for clinical applications in oral and maxillofacial surgery.

Study of the Potential of the Capsule Shell Based on Natural Polysaccharides in Targeted Delivery of the L-Phenylalanine Ammonia-Lyase Enzyme Preparation

The treatment of classical phenylketonuria is currently represented by many new methods of disease management. A promising method is the use of the enzyme L-phenylalanine ammonia-lyase (PAL) in various forms. The widespread use of enzyme preparations in therapy is limited by a lack of understanding of the mechanisms and systems of the targeted transport of PAL into certain organs and tissues as a result of the incorporation of a drug into the carrier. To ensure the stability of enzymes during the delivery process, encapsulation is preferable, which, as a rule, ensures the preservation of the qualitative characteristics of the enzymes orally applied to the environmental effects of the gastrointestinal tract (acidity, temperature, oxidation, etc.). Capsule preparations showed sufficient stability in the model gastric fluids and sustained release of the drug in the simulated intestinal fluid. Currently, there is a wide range of polymers used for encapsulation. The use of natural sources in the production technology of capsule systems improves bioavailability, controls the release, and prolongs the half-life of active substances. The advantage of this method is that the used enzyme is completely protected by the cell membranes of the capsules, which preserve its stability in the aggressive environment of the gastrointestinal tract. Capsules were obtained on the basis of compositions of hydrocolloids of plant origin. The potential of the developed capsules for targeted delivery of the enzyme preparation was studied. The degradation of the encapsulated form of the PAL enzyme preparation was studied in vitro in model bio-relevant media simulating the gastric and intestinal environment. The dynamics of the breakdown of the capsule shell allow us to expect that the release of L-phenylalanine ammonia-lyase from capsules based on plant hydrocolloids will occur no earlier than reaching the upper intestines, where the interaction with the protein components of the consumed food products to neutralize phenylalanine should occur.

Zinc and Calcium Cations Combination in the Production of Floating Alginate Beads as Prednisolone Delivery Systems

The aim of this research was to verify the application of alginate in combination with Ca²⁺ and Zn²⁺ ions to produce a floating and prolonged release system for the oral administration of prednisolone. Hollow and floating gel-beads were designed using prilling/ionotropic gelation as the microencapsulation technique, zinc acetate in the gelling solution as the alginate external crosslinker, and calcium carbonate in the feed as the internal crosslinking agent able to generate gas when in contact with the acidic zinc acetate solution. To achieve this goal, drug/alginate solutions were opportunely combined with different amounts of calcium carbonate. The effect of the addition of calcium carbonate into the feed solution on buoyancy, encapsulation efficiency, morphology, size distribution, as well as in vitro drug release profile of the alginate particles was studied. Moreover, the ability of the floating beads to modulate in vivo the anti-inflammatory response was assayed using the carrageenan-induced acute oedema in rat paw. The proposed strategy allowed obtaining alginate beads with extremely high encapsulation efficiency values (up to 94%) and a very porous inner matrix conferring buoyancy in vitro in simulated gastric fluid up to 5 h. Moreover, in vivo, the best formulation, F4, resulted in the ability to prolong the anti-inflammatory effect up to 15 h compared with raw prednisolone.

Pectin and Zinc Alginate: The Right Inner/Outer Polymer Combination for Core-Shell Drug Delivery Systems

Core-shell beads loaded with betamethasone were developed using co-axial prilling as production technique and pectin plus alginate as polymeric carriers. During this study, many operative conditions were intensively investigated to find the best ones necessary to produce uniform core-shell particle systems in a reproducible way. Particularly, feed solutions' composition, polymers mass ratios and the effect of the main process parameters on particles production, micromeritics, inner structure, drug loading and drug-release/swelling profiles in simulated biological fluids were studied. The optimized core-shell formulation F5 produced with a pectin core concentration of 4.0% w/v and an alginate shell concentration of 2.0% w/v (2:1 core:shell ratio) acted as a sustained drug delivery system. It was able to reduce the early release of the drug in the upper part of the gastro-intestinal tract for the presence of the zinc-alginate gastro-resistant outer layer and to specifically deliver it in the colon, thanks to the selectivity of amidated low methoxy pectin core for this district. Therefore, these particles may be proposed as colon targeted drug delivery systems useful for inflammatory bowel disease (IBD) therapy.

The Preparation and Structure Analysis Methods of Natural Polysaccharides of Plants and Fungi: A Review of Recent Development

Polysaccharides are ubiquitous biomolecules found in nature that contain various biological and pharmacological activities that are employed in functional foods and therapeutic agents. Natural polysaccharides are obtained mainly by extraction and purification, which may serve as reliable procedures to enhance the quality and the yield of polysaccharide products. Moreover, structural analysis of polysaccharides proves to be promising and crucial for elucidating structure–activity relationships. Therefore, this report summarizes the recent developments and applications in extraction, separation, purification, and structural analysis of polysaccharides of plants and fungi.

Natural Polysaccharides for siRNA Delivery: Nanocarriers Based on Chitosan, Hyaluronic Acid, and Their Derivatives

Natural polysaccharides are frequently used in the design of drug delivery systems due to their biocompatibility, biodegradability, and low toxicity. Moreover, they are diverse in structure, size, and charge, and their chemical functional groups can be easily modified to match the needs of the final application and mode of administration. This review focuses on polysaccharidic nanocarriers based on chitosan and hyaluronic acid for small interfering RNA (siRNA) delivery, which are highly positively and negatively charged, respectively. The key properties, strengths, and drawbacks of each polysaccharide are discussed. In addition, their use as efficient nanodelivery systems for gene silencing applications is put into context using the most recent examples from the literature. The latest advances in this field illustrate effectively how chitosan and hyaluronic acid can be modified or associated with other molecules in order to overcome their limitations to produce optimized siRNA delivery systems with promising in vitro and in vivo results.

Extraction and Characterization of Tamarind (Tamarind indica L.) Seed Polysaccharides (TSP) from Three Difference Sources

Tamarind seed polysaccharide (TSP), a natural polysaccharide extracted from tamarind seeds is used in the pharmaceutical, textile and food industries as a mucoadhesive polymer. This work aimed to extract TSP from tamarind seeds from three sources with two methods and characterized its physical and chemical properties. Kernel powder of tamarind seeds was slurried into a clear solution, set aside overnight and then centrifuged at 6000 rpm for 20 min to separate all foreign matter. The supernatant was separated and poured into excess 95% ethanol with continuous stirring. The precipitate obtained was collected and dried in the oven and then the dried TSP polymer was stored in a desiccator. The dried TSP was analyzed by ¹H-NMR, FT-IR and XRD. The results showed TSP from tamarind seeds taken from paddy farmland (A), a waste from the export tamarind juice industry (B) and the export tamarind powder industry(C) gave yields of 31.55%, 26.95% and 17.30%, respectively, using method 1 and 11.15%, 53.65% and 54.65%, with method 2, respectively, but method 2 gave purer TSP than method 1. The FT-IR spectra displayed peaks at 3351.95 cm⁻¹, 2920.76 cm⁻¹, 1018.85 cm⁻¹ and 555.16 cm⁻¹. The ¹H-NMR showed polysaccharide peaks between δ 3.50–4.20 ppm and XRD diagrams indicated their amorphous nature. Future works will focus on the quantitative analysis, biological activity and possible use of TSP as a drug delivery system.

Preparation of Fast Dissolving Films for Oral Dosage from Natural Polysaccharides

Fast-dissolving films (FDFs) were prepared from natural polysaccharides, such as pullulan, without heating, controlling the pH, or adding other materials. The release profiles of model drugs from the films were investigated. In the absence of a drug, the casting method and subsequent evaporation of the solvent resulted in the polysaccharide forming a circular film. The presence of drugs (both their type and concentration) affected film formation. The thickness of the film was controllable by adjusting the concentration of the polysaccharide, and regular unevenness was observed on the surface of 2% pullulan film. All films prepared with polysaccharides readily swelled in dissolution medium, released the incorporated compound, and subsequently disintegrated. The release of dexamethasone from the films was complete after 15 min, although this release rate was slightly slower than that of pilocarpine or lidocaine. Therefore, FDFs prepared from polysaccharides could be promising candidates as oral dosage forms containing drugs, and would be expected to show drug dissolution in the oral cavity.