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1.
4-Deoxy-l-erythro-5-hexoseulose Uronate (DEH) and DEH Reductase: Key Molecule and Enzyme for the Metabolism and Utilization of Alginate.
Kawai, S, Hashimoto, W
Molecules (Basel, Switzerland). 2022;(2)
Abstract
4-Deoxy-l-erythro-5-hexoseulose uronate (DEH), DEH reductase, and alginate lyase have key roles in the metabolism of alginate, a promising carbon source in brown macroalgae for biorefinery. In contrast to the widely reviewed alginate lyase, DEH and DEH reductase have not been previously reviewed. Here, we summarize the current understanding of DEH and DEH reductase, with emphasis on (i) the non-enzymatic and enzymatic formation and structure of DEH and its reactivity to specific amino groups, (ii) the molecular identification, classification, function, and structure, as well as the structural determinants for coenzyme specificity of DEH reductase, and (iii) the significance of DEH for biorefinery. Improved understanding of this and related fields should lead to the practical utilization of alginate for biorefinery.
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2.
Alginate modification via click chemistry for biomedical applications.
Deng, Y, Shavandi, A, Okoro, OV, Nie, L
Carbohydrate polymers. 2021;:118360
Abstract
Alginate biopolymers are characterized by favorable properties, of biocompatibility, degradability, and non-toxicity. However, the poor stability properties of alginate have limited its suitability for diverse applications. Recently, click chemistry has generated significant research interest due to its high reaction efficiency, high selectivity for a single product, harmless byproducts, and processing simplicity. Alginate modified using click chemistry enables the production of alginate derivatives with enhanced physical and chemical properties. Herein, we review the employment of click chemistry in the development of alginate-based materials or systems. Various click chemistries were highlighted, including azide and alkyne cycloaddition (e.g. Copper-(I)-catalyzed azide-alkyne cycloaddition (CuAAC), Strain-promoted alkyne-azide cycloaddition (SPAAC)), Diels-Alder reaction (Inverse electron demand Diels-Alder (IEDDA) cycloaddition, Tetrazine-norbornene Diels-Alder reactions), Thiol-ene/yne addition (Free-radical thiol-ene addition click reactions, Thiol-Michael addition click reactions, Thiol-yne addition click reaction), Oxime based click reactions, and other click reactions. Alginate functionalized with click chemistry and its properties were also discussed. The present study shows that click chemistry may be employed in modifying the mechanical strength, biochemical/biological properties of alginate-based materials. Finally, the applications of alginate-based materials in wound dressing, drug delivery, protein delivery, tissue regeneration, and 3D bioprinting were described and the future perspectives of alginates modified with click chemistry, are subsequently presented. This review provides new insights for readers to design structures and expand applications of alginate using click chemistry reactions in a detailed and more rational manner.
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3.
Adsorption of heavy metal ions by sodium alginate based adsorbent-a review and new perspectives.
Gao, X, Guo, C, Hao, J, Zhao, Z, Long, H, Li, M
International journal of biological macromolecules. 2020;:4423-4434
Abstract
With the development of modern industry, heavy metal pollution is one of the most important environmental issues. Due to its simplicity and low-cost, adsorption is considered as a green and environmental friendly method to remove heavy metals from industrial effluents. Sodium alginate is a natural polysaccharide, which consists of abundant hydroxyl and carboxyl groups, has been widely reported as the raw material for the adsorption of heavy metals from aqueous solutions. By surface grafting and cross-linking, adsorbents synthesized from sodium alginate have exhibited large uptake capacities as well as high removal rates for heavy metal ions. However, the poor physical strength and plain thermostability have significantly limited the utilization of sodium alginate based materials in industrial applications. Moreover, reductions of specific metal ions were observed in some studies, of which the reduction mechanism is not clearly clarified. In this work, the development of sodium alginate based adsorbents was summarized, including the physicochemical properties of the polymer, the modification of sodium alginate, sodium alginate based composite materials, and the adsorption behaviors as well as the mechanism. Chelation, electrostatic interaction, ion exchange, reduction and photocatalytic reduction were involved in the adsorption process, which can be determined by chemical characterization with further elucidation by density functional theory calculation. Finally, the limitations of sodium alginate based adsorbents were revealed with suggestions for future research.
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4.
Alginate as Promising Natural Polymer for Pharmaceutical, Food, and Biomedical Applications.
Kothale, D, Verma, U, Dewangan, N, Jana, P, Jain, A, Jain, D
Current drug delivery. 2020;(9):755-775
Abstract
Alginates are biopolymers usually obtained from brown seaweed, brown algae (Ochrophyta, Phaeophyceae), and bacteria (Azatobacter vineland and Pseudomonas species) belonging to the family of polycationic copolymers. They are biocompatible, biodegradable, non-antigenic, and non-toxic biopolymer with molecular mass ranges from 32,000-40,000 g/mol in commercial grades. These can be used as edible films or coatings in food industries and also some natural or chemical additives could be incorporated into them to modify their functional, mechanical, nutritional as well as organoleptic properties. Due to their high viscosity and extraordinary shear-thinning effect, they can be used as dietary fibers, thickening, gelling and stabilizing agents. Commercial alginates have vast applications in the fields of biomedical engineering, biotechnology, environmental contaminants treatments, food processing, and pharmaceuticals. Alginates can be used in wound dressings, bone regeneration, neovascularization, protein delivery, cell delivery, theranostic agents, oral drug delivery, controlled release systems, raft formulations, immobilization of biological agents and treatment of environmental contaminants. Various carrier systems can be formulated by the use of alginates like hydrogel, tablets, microcapsules, films, matrices, microspheres, liposomes, nanoparticles, beads, cochleate, floating and supersaturated drug delivery systems. This review presents a broad range of promising applications of alginates, and it can be a great interest to scientists and industries engaged in exploring its hidden potential.
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5.
Alginate Nanoparticles for Drug Delivery and Targeting.
Severino, P, da Silva, CF, Andrade, LN, de Lima Oliveira, D, Campos, J, Souto, EB
Current pharmaceutical design. 2019;(11):1312-1334
Abstract
Nanotechnology refers to the control, manipulation, study and manufacture of structures and devices at the nanometer size range. The small size, customized surface, improved solubility and multi-functionality of nanoparticles will continue to create new biomedical applications, as nanoparticles allow to dominate stability, solubility and bioavailability, as well controlled release of drugs. The type of a nanoparticle, and its related chemical, physical and morphological properties influence its interaction with living cells, as well as determine the route of clearance and possible toxic effects. This field requires cross-disciplinary research and gives opportunities to design and develop multifunctional devices, which allow the diagnosis and treatment of devastating diseases. Over the past few decades, biodegradable polymers have been studied for the fabrication of drug delivery systems. There was extensive development of biodegradable polymeric nanoparticles for drug delivery and tissue engineering, in view of their applications in controlling the release of drugs, stabilizing labile molecules from degradation and site-specific drug targeting. The primary aim is to reduce dosing frequency and prolong the therapeutic outcomes. For this purpose, inert excipients should be selected, being biopolymers, e.g. sodium alginate, commonly used in controlled drug delivery. Nanoparticles composed of alginate (known as anionic polysaccharide widely distributed in the cell walls of brown algae which, when in contact with water, forms a viscous gum) have emerged as one of the most extensively characterized biomaterials used for drug delivery and targeting a set of administration routes. Their advantages include not only the versatile physicochemical properties, which allow chemical modifications for site-specific targeting but also their biocompatibility and biodegradation profiles, as well as mucoadhesiveness. Furthermore, mechanical strength, gelation, and cell affinity can be modulated by combining alginate nanoparticles with other polymers, surface tailoring using specific targeting moieties and by chemical or physical cross-linking. However, for every physicochemical modification in the macromolecule/ nanoparticles, a new toxicological profile may be obtained. In this paper, the different aspects related to the use of alginate nanoparticles for drug delivery and targeting have been revised, as well as how their toxicological profile will determine the therapeutic outcome of the drug delivery system.
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6.
Kinetic investigation of a controlled drug delivery system based on alginate scaffold with embedded voids.
Bhasarkar, J, Bal, D
Journal of applied biomaterials & functional materials. 2019;(2):2280800018817462
Abstract
Alginate scaffold has been used widely for controlled release applications because of its ability to provide three-dimensional supports for formation of a gel matrix. Alginate gel scaffolds for drug delivery matrices were prepared using a fluidic device. N2 gas was used in the fluidic device to generate bubbles in the gel layer. The hydrogel matrices with induced voids were compared with hydrogel matrices without voids. This study attempted to identify the release mechanism of vitamin B12 from the two types of prepared scaffolds, and the data were fitted with different release kinetic models. The results revealed that the alginate scaffold exhibited a controlled release profile and that the corresponding release mechanism followed a first-order kinetic model. Hydrogel scaffolds fabricated with biocompatible polymers using fluidic methods could be promising for controlled drug delivery systems.
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7.
Alginate gel particles-A review of production techniques and physical properties.
Ching, SH, Bansal, N, Bhandari, B
Critical reviews in food science and nutrition. 2017;(6):1133-1152
Abstract
The application of hydrocolloid gel particles is potentially useful in food, chemical, and pharmaceutical industries. Alginate gel particles are one of the more commonly used hydrocolloid gel particles due to them being biocompatible, nontoxic, biodegradable, cheap, and simple to produce. They are particularly valued for their application in encapsulation. Encapsulation in alginate gel particles confers protective benefits to cells, DNA, nutrients, and microbes. Slow release of flavors, minerals, and drugs can also be achieved by encapsulation in gel particles. The particle size and shape of the gel particles are crucial for specific applications. In this review, current methods of producing alginate gel particles will be discussed, taking into account their advantages, disadvantages, scalability, and impact on particle size. The physical properties of alginate gel particles will determine the effectiveness in different application conditions. This review will cover the current understanding of the alginate biopolymer, gelation mechanisms and factors affecting release properties, gel strength, and rheology of the alginate gel particle systems.
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8.
Use of viscous fibres in beverages for appetite control: a review of studies.
Ho, IH, Matia-Merino, L, Huffman, LM
International journal of food sciences and nutrition. 2015;(5):479-90
Abstract
Dietary fibres, particularly viscous fibres appear to be more effective for appetite control (reduce subjective appetite, energy intake and/or body weight). Three types of viscous fibres, pectin, alginate and cereal beta-glucan, were identified as potential satiety-enhancing ingredients. The aim of this review was to collect evidence from human intervention studies evaluating pectins, alginates and beta-glucans in beverages, liquid preloads and liquid test meals for their satiety effects. Our focused, narrative review of several satiety studies shows an overall consistent result on the effectiveness of pectin, alginate and beta-glucan for appetite control. Beverages or liquid test meals are probably the better delivery mode for these fibres, as their effect on satiety is affected by their physico-chemical properties. Most, if not all, of these reviewed studies gave little or no consideration to the potential effects of common food processing (e.g. pasteurisation, ultra-high temperature process) on the physico-chemical properties of these fibre-containing beverages. This is one of the research gaps we have identified warranting further work, which is likely to be of significance from the industry and consumer perspective.
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9.
Effect of the novel functional fibre, polyglycoplex (PGX), on body weight and metabolic parameters: A systematic review of randomized clinical trials.
Onakpoya, IJ, Heneghan, CJ
Clinical nutrition (Edinburgh, Scotland). 2015;(6):1109-14
Abstract
BACKGROUND & AIMS Hundreds of dietary supplements are marketed as weight loss pills, but the evidence for effectiveness for most is unproven. The objective of this review was to critically appraise and evaluate the evidence from published randomized clinical trials (RCTs) examining the effectiveness of polyglycoplex (PGX), a novel functional fibre, on body weight and metabolic parameters. METHODS We conducted electronic searches in Medline, Embase, Amed, Cinahl and The Cochrane Library. Only double-blinded RCTs were considered for inclusion. The reporting quality of included studies was assessed using the Cochrane criteria. Two reviewers independently determined eligibility, assessed the quality of reporting, and extracted the data. RESULTS We included four RCTs with a total of 217 participants. The RCTs varied in the quality of their reporting. The evidence from the RCTs suggested that PGX has no significant effects on body weight; however, significant reductions were noted for total and LDL cholesterol. Adverse events reported included diarrhea and abdominal bloating. CONCLUSION The evidence from available RCTs does not indicate that PGX intake causes reductions in body weight. PGX may cause reductions in total and LDL cholesterol. Few trials examining the effects of PGX have been conducted; they are characterized by small sample sizes, deficiencies in reporting quality, and are funded by a single manufacturer. Future clinical trials evaluating its effect should be adequately powered and better reported.
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10.
Microenvironment of alginate-based microcapsules for cell culture and tissue engineering.
Huang, X, Zhang, X, Wang, X, Wang, C, Tang, B
Journal of bioscience and bioengineering. 2012;(1):1-8
Abstract
As a type of 3D model, the technology of microencapsulation holds significant promise for tissue engineering and cell therapy due to its unique performance. The microenvironmental factors within microcapsules play an important role in influencing the behaviors of encapsulated cells. The aim of this review article is to give an overview on the construction of the microenvironmental factors, which include 3D space, physicochemical properties of alginate matrix, cell spheroids, nutritional status, and so on. Furthermore, we clarified the effect of microenvironmental factors on the behaviors of encapsulated cells and the methods about improving the microenvironment of microcapsules. This review will help to understand the interaction of the microenvironment and the encapsulated cells and lay a solid foundation for microcapsule-based cell therapy and tissue engineering.