Polysaccharides

Insect-derived chitin and chitosan have gained interest as alternative sources to that derived from crustaceans; however, little information is available on chitin from the house cricket (Acheta domesticus) and tropical banded cricket (Gryllodes sigillatus), two cricket species commonly reared in the United States for human consumption. In this study, chitin was successfully isolated and purified from these two cricket species; using FTIR, chitins were found to be in alpha-crystalline form. Cricket chitosan was produced from both species with varying degrees of deacetylation (DDA) by varying alkaline conversion duration. G. sigillatus chitosan was larger (524 kDa) than A. domesticus chitosan (344 kDa). Both cricket chitosans showed similar (p > 0.05) lipid-binding capacity to that of shrimp chitosan. Both chitosans were as effective at inhibiting microbial growth of surrogate foodborne pathogens as the commercial shrimp chitosan. At a concentration of 0.50 mg/mL cricket chitosan, approximately 100% of Listeria innocua growth was inhibited, due to a contribution of both chitosan and the solvent-acetic acid. At the same concentration, growth of Escherichia coli was inhibited 90% by both cricket chitosan samples with ~80% DDA, where a decrease in the DDA led to decreased antimicrobial activity. However, varying the DDA had no effect on chitosan’s lipid-binding capacity. As more edible insects become a normalized protein source in our diet, the use of by-products, such as chitin and chitosan, derived from insect protein processing, show promising applications for the pharmaceutical and food industries. Full article

Exosomes (EXOs) are nano-sized informative shuttles acting as endogenous mediators of cell-to-cell communication. Their innate ability to target specific cells and deliver functional cargo is recently claimed as a promising theranostic strategy. The glycan profile, actively involved in the EXO biogenesis, release, sorting and function, is highly cell type-specific and frequently altered in pathological conditions. Therefore, the modulation of EXO glyco-composition has recently been considered an attractive tool in the design of novel therapeutics. In addition to the available approaches involving conventional glyco-engineering, soft technology is becoming more and more attractive for better exploiting EXO glycan tasks and optimizing EXO delivery platforms. This review, first, explores the main functions of EXO glycans and associates the potential implications of the reported new findings across the nanomedicine applications. The state-of-the-art of the last decade concerning the role of natural polysaccharides—as targeting molecules and in 3D soft structure manufacture matrices—is then analysed and highlighted, as an advancing EXO biofunction toolkit. The promising results, integrating the biopolymers area to the EXO-based bio-nanofabrication and bio-nanotechnology field, lay the foundation for further investigation and offer a new perspective in drug delivery and personalized medicine progress. Full article

Lignocellulosic residues have been receiving growing interest as a promising source of polysaccharides, which can be converted into a variety of compounds, ranging from biofuels to bioplastics. Most of these can replace equivalent products traditionally originated from petroleum, hence representing an important environmental advantage. Lignocellulosic materials are theoretically unlimited, cheaper and may not compete with food crops. However, the conversion of these materials to simpler sugars usually requires cellulolytic enzymes. Being still associated with a high cost of production, cellulases are commonly considered as one of the main obstacles in the economic valorization of lignocellulosics. This work provides a brief overview of some of the most studied strategies that can allow an important reduction of cellulases consumption, hence improving the economy of lignocellulosics conversion. Cellulases recycling is initially discussed regarding the main processes to recover active enzymes and the most important factors that may affect enzyme recyclability. Similarly, the potential of enzyme immobilization is analyzed with a special focus on the contributions that some elements of the process can offer for prolonged times of operation and improved enzyme stability and robustness. Finally, the emergent concept of consolidated bioprocessing (CBP) is also described in the particular context of a potential reduction of cellulases consumption. Full article

New biomimetic micro- and nano-CsU-based fibrous scaffolds electrospun from solution containing high purity-medical grade chitosan (CsU) of fungus origin (CsU1, Mv ~174,000 and CsU2, 205,000, degree of deacetylation (DDA) ~65%) and polyethylene oxide (PEO, Mv ~ 900,000), in the presence of given amounts of Triton X-100 (from 0.01 to 0.5 wt%) as surfactant were fabricated. We demonstrate that by carefully selecting compositions and surfactant levels, porous mats with CsU content up to 90% (at this molecular weight and DDA) were achieved. Remarkable long-term stability in water or phosphate buffer solution storage were obtained by developing post-electrospinning treatment allowing the complete elimination of the PEO from the CsU-fibers as demonstrated by TGA, DSC and ESEM analysis. Subsequent reacetylation procedure was applied to convert 2D biomimetic chitosan mats to chitin (CsE)-based ones while preserving the nanofiber structure. This innovative procedure allows tuning and modifying the thermal, mechanical properties and more importantly the biodegradation abilities (fast enzymatic biodegradation in some cases and slower on the others) of the prepared nanofibrous mats. The established reproducible method offers the unique advantage to modulate the membrane properties leading to stable 2D biomimetic CsU and/or chitin (CsE) scaffolds tailor-made for specific purposes in the field of tissue engineering. Full article

Cellulose is the most common biopolymer and widely used in our daily life. Due to its unique properties and biodegradability, it has been attracting increased attention in the recent years and various new applications of cellulose and its derivatives are constantly being found. The development of new materials with improved properties, however, is not always an easy task, and theoretical models and computer simulations can often help in this process. In this review, we give an overview of different coarse-grained models of cellulose and their applications to various systems. Various coarse-grained models with different mapping schemes are presented, which can efficiently simulate systems from the single cellulose fibril/crystal to the assembly of many fibrils/crystals. We also discuss relevant applications of these models with a focus on the mechanical properties, self-assembly, chiral nematic phases, conversion between cellulose allomorphs, composite materials and interactions with other molecules. Full article

Raw wood was subjected to sequential oxidation to produce 2,3,6-tricarboxycellulose (TCC) nanofibers with a high surficial charge of 1.14 mmol/g in the form of carboxylate groups. Three oxidation steps, including nitro-oxidation, periodate, and sodium chlorite oxidation, were successfully applied to generate TCC nanofibers from raw wood. The morphology of extracted TCC nanofibers measured using TEM and AFM indicated the average length, width, and thickness were in the range of 750 ± 110, 4.5 ± 1.8, and 1.23 nm, respectively. Due to high negative surficial charges on TCC, it was studied for its absorption capabilities against Pb²⁺ ions. The remediation results indicated that a low concentration of TCC nanofibers (0.02 wt%) was able to remove a wide range of Pb²⁺ ion impurities from 5–250 ppm with an efficiency between 709–99%, whereby the maximum adsorption capacity (Q_m) was 1569 mg/g with R² 0.69531 calculated from Langmuir fitting. It was observed that the high adsorption capacity of TCC nanofibers was due to the collective effect of adsorption and precipitation confirmed by the FTIR and SEM/EDS analysis. The high carboxylate content and fiber morphology of TCC has enabled it as an excellent substrate to remove Pb²⁺ ions impurities. Full article

This review examines the production of the microbial polysaccharide gellan, synthesized by Sphingomonas elodea, on dairy and plant-based processing coproducts. Gellan is a water-soluble gum that structurally exists as a tetrasaccharide comprised of 20% glucuronic acid, 60% glucose and 20% rhamnose, for which various food, non-food and biomedical applications have been reported. A number of carbon and nitrogen sources have been tested to determine whether they can support bacterial gellan production, with several studies attempting to optimize gellan production by varying the culture conditions. The genetics of the biosynthesis of gellan has been explored in a number of investigations and specific genes have been identified that encode the enzymes responsible for the synthesis of this polysaccharide. Genetic mutants exhibiting overproduction of gellan have also been identified and characterized. Several dairy and plant-based processing coproducts have been screened to learn whether they can support the production of gellan in an attempt to lower the cost of synthesizing the microbial polysaccharide. Of the processing coproducts explored, soluble starch as a carbon source supported the highest gellan production by S. elodea grown at 30 °C. The corn processing coproducts corn steep liquor or condensed distillers solubles appear to be effective nitrogen sources for gellan production. It was concluded that further research on producing gellan using a combination of processing coproducts could be an effective solution in lowering its overall production costs. Full article

This study aimed to produce modified cellulose extracted from oat hulls by an esterification reaction with citric acid (CA) employing ultrasonication and reactive extrusion assisted processes. Modified samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (DRX), scanning electron microscopy (SEM), wettability, oil and water absorption capacities, water adsorption capacity, and thermal stability. From FTIR results it can be observed a new band for all modified samples at 1735 cm⁻¹, confirming the esterification. The morphology and crystallinity pattern of fibers were not affected by esterification, and crystallinity indexes ranged from 43% (unmodified cellulose) to 44–49% in modified samples. Both groups of samples, obtained by ultrasonication and reactive extrusion, showed decreases in water absorption capacities (1.63–1.71 g/g) compared to unmodified cellulose (9.38 g/g). It was observed an increase in oil retention capacity from 1.80 g/g (unmodified cellulose) to 4.57–7.31 g/g after esterification, and also the modified samples presented higher affinity by a non-polar solvent in the wettability test. The new properties of modified cellulose expand its use in the industry and prove that ultrasonication and reactive extrusion can be used to obtain esterified cellulose, being eco-friendly, simple, and convenient processes with short reaction times. Full article

Macroalgae are the primary source of non-animal sulphated polysaccharides (SPs) in the marine environment with fucoidans derived from brown algae (Phaeophyta) and carrageenans from red algae (Rhodophyta). Much research has been carried out on SP effects on Asian shrimp species (genera Penaeus and Metapenaeus) but their effect on commercially important bivalve mollusc species is limited and in Pacific oyster Crassostrea gigas is unknown. Knowledge of their impact on bivalve pathogens and Palaemon shrimp is unknown. The objectives of this study were to assess the effects of Fucus vesiculosus (Phaeophyta), Mastocarpus stellatus (Rhodophyta) and algal derivatives (fucoidan and κ-carrageenan) on C. gigas performance, and on ostreid herpesvirus-1 microvar (OsHV-1 μVar) and bacteria Vibrio spp. development. Both pathogens have been associated with significant oyster mortalities and economic losses globally. The effects of sulphated galactan from Gracilaria fisheri (Rhodophyta) on European common prawn Palaemon serratus, an important fishery species, was also assessed. Findings indicate a rapid and prolonged increase in total blood cell count, lysozyme (enzyme that destroys pathogens), and a difference in the ratio of blood cell types in treated individuals compared to their control counterparts. A significantly lower OsHV-1 μVar prevalence was observed in treated oysters and κ-carrageenan was found to suppress viral replication (loads), while OsHV-1 μVar was not detected in the fucoidan treated oysters from Day 8 of the 26-day trial. No antibacterial effect was observed however, the oysters did not succumb to vibriosis. These findings contribute further knowledge to macroalgae sulphated polysaccharide biotherapeutic properties, their twofold effect on animal health and viral suppression. Full article

Amylose is well known to be organized helically with six glucose per turn, allowing it to form complexes with various ligands. This interaction can be affected by the type of crystalline structure present in the starch sources. This study evaluated the effect of extrusion on the crystalline structure of starch during RS5 formation. Rice and potato starches were extruded at 100 °C and 15 rpm with 5% and 10% oleic acid (OA), then the physical, thermal, paste properties, and resistant starch content (RS) were evaluated. Potato starch extruded with 10% OA showed granules embedded in a gelatinized starch matrix. The X-ray revealed that rice (orthorhombic) and potato (hexagonal) structures remain unchanged even after extrusion. Differential scanning calorimetry (DSC) evidenced the formation of type IIa amylose-lipid complexes in OA treatments, where potato extruded with 10% OA had the highest enthalpy (0.9 J/g). Moreover, the extruded potato showed the highest pasting temperature (87.19 °C), supporting the complex formation. The RS was reduced from 15.8 (isolated) to 4.14 mg/100 mg (extruded 10% OA) in rice. For potato, RS decreased from 17 to 13 mg/100 mg (isolated and extruded 10% OA). Overall, these findings suggest a tendency in potato starch (ortho-rhombic) to interact with OA during the extrusion process, promoting a crystalline lamellae growth when extruded with 10% OA; therefore, changing their properties. Full article

The nanoreactor concept and its application as a modality to carry out chemical reactions in confined and compartmentalized structures continues to receive increasing attention. Micelle-based nanoreactors derived from various classes of surfactant demonstrate outstanding potential for chemical synthesis. Polysaccharide (glycan-based) surfactants are an emerging class of biodegradable, non-toxic, and sustainable alternatives over conventional surfactant systems. The unique structure of glycan-based surfactants and their micellar structures provide a nanoenvironment that differs from that of the bulk solution, and supported by chemical reactions with uniquely different reaction rates and mechanisms. In this review, the aggregation of glycan-based surfactants to afford micelles and their utility for the synthesis of selected classes of reactions by the nanoreactor technique is discussed. Glycan-based surfactants are ecofriendly and promising surfactants over conventional synthetic analogues. This contribution aims to highlight recent developments in the field of glycan-based surfactants that are relevant to nanoreactors, along with future opportunities for research. In turn, coverage of research for glycan-based surfactants in nanoreactor assemblies with tailored volume and functionality is anticipated to motivate advanced research for the synthesis of diverse chemical species. Full article

For the creation of tissue-engineered structures based on natural biopolymers with the necessary chemical, physical, adhesive, morphological, and regenerative properties, biocompatible materials based on polysaccharides and proteins are used. This work is devoted to a problem of the technology of polymeric materials for biomedical purposes: the creation of biopolymer tissue engineering matrix and the development of a methodology for studying morphology and functional properties of their surface to establish the prospects for using the material for contact with living objects. The conditions for the formation of scaffolds based on composite materials of chitosan and fibroin determine the structure of the material, the thickness and orientation of molecular layers, the surface morphology, and other parameters that affect cell adhesion and growth. The analysis of studies of the morphology and properties of the surface of biopolymer matrices obtained using different methods of molding from solutions of chitosan and fibroin is carried out. Full article

The recycling of cellulose from cotton textiles would minimize the use of virgin crop fibers, but recycled polymers are generally inferior in mechanical performance to those made from virgin resins. This challenge prompted the investigation of biobased additives that were capable of improving the mechanical properties of fibers by means of antiplasticizing additives. In this study, regenerated cellulose (RC) fibers were spun from cellulose found in cotton T-shirts, and fibers were mechanically strengthened with glucaric acid (GA), a nontoxic product of fermentation. The recycled pulp was activated using aqueous sodium hydroxide and then followed by acid neutralization, prior to the direct dissolution in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) at 3 wt.% cellulose. At 10% (w/w) GA, the tensile modulus and strength of regenerated cellulose from recycled cotton fibers increased five-fold in contrast to neat fibers without GA. The highest modulus and tenacity values of 664 cN/dtex and of 9.7 cN/dtex were reported for RC fibers containing GA. Full article

In recent years there has been a significant effort from food, nutraceutical, cosmeceutical, pharmaceutical, and biomedical industries to discover and develop new natural ingredients. Microalgae have been recognised as potential sources of high value chemicals, with most attention focused upon antioxidants, pigments, and specialty oils. An under-exploited group of biochemicals produced by microalgae are extracellular polymeric substances (EPS). Lobochlamys segnis (formerly called Chlamydomonas segnis) was previously reported to produce a large amount of capsular polysaccharide (CPS) closely related to hyaluronan (HA) under stress conditions. In this work, the purified CPS was characterised and shown to have an average molecular mass (Mn) of about 3.7 MDa, and displayed a highly branched random coil structure unlike the simple repeating linear HA polysaccharide. Chemical analysis showed the presence of galactose, glucuronic acid, and glucose sugars confirming that the product has a different composition to that of HA. Mixotrophic growth and stress conditions were identified and improved upon with a pH control system using acetic acid solution to induce efficient production of CPS. Extraction and purification conditions were also identified exploiting the high Mn of the product. The CPS showed thickening properties and both significant antioxidant capacity and reducing power, which could have commercial applications. This is the first report on the characterization of this novel polysaccharide with non-Newtonian properties similar to HA. Full article

Commercial adhesives present a high bond strength and water resistance, but they are considered non-healthier products. Chitosan can be considered as an interesting biosourced and biodegradable alternative, despite its low water resistance. Here, its wood bonding implementation and its tensile shear strength in dry and wet conditions were investigated depending on its structural characteristics. Firstly, the spread rate, open assembly time, drying pressure, drying temperature, and drying time have been determined for two chitosans of European pine double lap specimens. An adhesive solution spread rate of 1000 g·m⁻², an open assembly time of 10 min, and a pressure temperature of 55 °C for 105 min led to a bond strength of 2.82 MPa. Secondly, a comparison between a high molecular weight/low deacetylation degree chitosan and a lower molecular weight/higher deacetylation degree chitosan was conducted. Tests were conducted with beech simple lap specimens in accordance with the implementation conditions and the conditioning treatments in wet and dry environments required for thermoplastic wood adhesive standards used in non-structural applications (EN 204 and EN 205). The results clearly revealed the dependence of adhesive properties and water resistance on the structural features of chitosans (molecular weight and deacetylation degree), explaining the heterogeneity of results published notably in this field. Full article

Bacterial transformation and gene transfection can be understood as being the results of introducing specific genetic material into cells, resulting in gene expression, and adding a new genetic trait to the host cell. Many studies have been carried out to investigate different types of lipids and cationic polymers as promising nonviral vectors for DNA transfer. The present study aimed to carry out a systematic review on the use of biopolymeric materials as nonviral vectors. The methodology was carried out based on searches of scientific articles and applications for patents published or deposited from 2006 to 2020 in different databases for patents (EPO, USPTO, and INPI) and articles (Scopus, Web of Science, and Scielo). The results showed that there are some deposits of patents regarding the use of chitosan as a gene carrier. The 16 analyzed articles allowed us to infer that the use of biopolymers as nonviral vectors is limited due to the low diversity of biopolymers used for these purposes. It was also observed that the use of different materials as nonviral vectors is based on chemical structure modifications of the material, mainly by the addition of cationic groups. Thus, the use of biopolymers as nonviral vectors is still limited to only a few polysaccharide types, emphasizing the need for further studies involving the use of different biopolymers in processes of gene transfer. Full article

Surgicel^® (regenerated oxidized cellulose) is a bio-absorbable hemostatic material widely applied to prevent surgery-derived adhesions. Some critical issues have been reported associated with this biomaterial, which we aimed to overcome by producing bacterial nanocellulose (BNC) membranes with hemostatic activity, through electrochemical oxidation using the tetramethylpiperidine-1-oxyl (TEMPO) radical. Samples were characterized by FTIR, NMR, SEM, XRD and their degree of polymerization. The oxidation degree was evaluated by titration of the carboxyl groups and the hemostatic behavior by whole-blood-clotting assays. In vitro and in vivo biodegradability of oxidized BNC membranes were evaluated and compared with that of Surgicel^®. The oxidation degree increased from 4% to 7% and up to 15%, corresponding to an applied charge of 400, 700 and 1200 Coulombs, respectively. The oxidized BNC preserved the crystallinity and the 3D nano-fibrillar network, and demonstrated hemostatic activity, although not as effective as that of Surgicel^®. In vivo assays demonstrated that the oxidized membranes did not induce an inflammatory response, revealing a good biocompatibility. However, non-degraded oxidized BNC was still detected at the implantation site after 56 days. Full article

Didymosphenia geminata diatoms, or Didymo, was first found to be an invasive species that could have negative impacts on the environment due to the aggressive growth of its polysaccharide-based stalks. The stalks’ adhesive properties have prompted park officials to alert the general public to limit further spread and contamination of this algae to other bodies of water. Although the negative effects of Didymo have been studied in the past, recent studies have demonstrated a potential positive side to this alga. One of the potential benefits includes the structural component of the polysaccharide stalks. The origin of the polysaccharides within stalks remains unknown; however, they can be useful in a waste management and agricultural setting. The primary purpose of this study was to describe both the harmful and beneficial nature of Didymo. Important outcomes include findings related to its application in various fields such as medicine and technology. These polysaccharides can be isolated and studied closely to produce efficient solar power cells and batteries. Though they may be harmful while uncontained in nature, they appear to be very useful in the technological and medical advancement of our society. Full article

Toxic metal contamination has serious effects on human health. Crude oil that may contain toxic metals and oil spills can further contaminate the environment and lead to increased exposure. This being the case, we chose to study the bio-production of inexpensive, environmentally safe materials for remediation. Streptomyces sp. MOE6 is a Gram-positive, filamentous bacterium from soil that produces an extracellular polysaccharide (MOE6-EPS). A one-factor-at-a-time experiments showed that the maximum production of MOE6-EPS was achieved at 35 °C, pH 6, after nine days of incubation with soluble starch and yeast extract as carbon sources and the latter as the nitrogen source. We demonstrated that MOE6-EPS has the capacity to remove toxic metals such as Co(II), Cr(VI), Cu(II) and U(VI) and from solution either by chelation and/or reduction. Additionally, the bacterium was found to produce siderophores, which contribute to the removal of metals, specifically Fe(III). Additionally, purified MOE6-EPS showed emulsifying activities against various hydrophobic substances, including olive oil, corn oil, benzene, toluene and engine oil. These results indicate that EPS from Streptomyces sp. MOE6 may be useful to sequester toxic metals and oil in contaminated environments. Full article