Chitin-glucan complex – Based biopolymeric structures using biocompatible ionic liquids

Unveiling the structural properties and induced resistance activity in rice of Chitin/Chitosan-Glucan Complex of Rhizoctonia solani AG1 IA inner cell wall

Phytopathogen cell wall polysaccharides have important physiological functions. In this study, we isolated and characterized the alkali-insoluble residue on the inner layers of the Rhizoctonia solani AG1 IA cell wall (RsCW-AIR). Through chemical composition and structural analysis, RsCW-AIR was mainly identified as a complex of chitin/chitosan and glucan (ChCsGC), with glucose and glucosamine were present in a molar ratio of 2.7:1.0. The predominant glycosidic bond linkage of glucan in ChCsGC was β-1,3-linked Glcp, both the α and β-polymorphic forms of chitin were presented in it by IR, XRD, and solid-state NMR, and the ChCsGC exhibited a degree of deacetylation measuring 67.08 %. RsCW-AIR pretreatment effectively reduced the incidence of rice sheath blight, and its induced resistance activity in rice was evaluated, such as inducing a reactive oxygen species (ROS) burst, leading to the accumulation of salicylic acid (SA) and the up-regulation of SA-related gene expression. The recognition of RsCW-AIR in rice is partially dependent on CERK1.

Extraction of chitin-glucan complex from shiitake (Lentinula edodes) fruiting bodies using natural deep eutectic solvents and its prebiotic potential

Chitin-glucan complex (CGC) is an emerging novel prebiotic with numerous physiological activities in amelioration of clinical manifestations. In the present work, natural deep eutectic solvent (NADES), ultrasonication, and submerged fermentation using probiotic microorganisms were deployed for the extraction of CGC from Shiitake fruiting bodies. CGC obtained through non-ultrasonication assisted fermentation employing Lactiplantibacillus plantarum exhibited maximum polysaccharide yield (27.86 ± 0.82 % w/w). However, based on antioxidant potential, NADES combination of urea: glycerol (1:1 M ratio) was selected for further characterization. The rheological behavior of CGC under optimized conditions showed shear thinning property in both 0.1 M NaCl and salt-free solution. FTIR, 1H-(1D), and 2D 1H1H Homonuclear NMR spectra displayed distinctive patterns associated with β-glycosidic linkage and β-d-glucopyranose sugar moiety. XRD profiles of CGC exhibited characteristic peaks at 2θ = 23°, 25°, and 28° with corresponding hkl values of (220), (101), and (130) lattice planes, respectively. Enhanced radical scavenging activities were noticed due to the triple helical structure and anionic nature of CGC. CGC exhibited potential prebiotic activity (prebiotic score 118-134 %) and short chain fatty acids liberation (maximum 9.99 ± 0.41 mM by Lactobacillus delbrueckii). Simulated static in-vitro digestion demonstrated that CGC withstands acidic environment of gastric phase, which indicated its suitability for use as a prebiotic in nutraceutical-enriched food products.

Cytotoxicity and Inflammatory Effects of Chitin Nanofibrils Isolated from Fungi

Fungal nanochitin can assist the transition from the linear fossil-based economy to a circular biobased economy given its environmental benefits over conventional crustacean-nanochitin. Its real-world implementation requires carefully assessing its toxicity so that unwanted human health and environmental issues are avoided. Accordingly, the cytotoxicity and inflammatory effects of chitin nanofibrils (ChNFs) from white mushroom is assessed. ChNFs are few nanometers in diameter, with a 75.8% N-acetylation degree, a crystallinity of 59.1%, and present a 44:56 chitin/glucan weight ratio. Studies are conducted for aqueous colloidal ChNF dispersions (0-5 mg·mL-1) and free-standing films having physically entangled ChNFs. Aqueous dispersions of chitin nanocrystals (ChNCs) isolated via hydrochloric acid hydrolysis of α-chitin powder are also evaluated for comparison. Cytotoxicity studies conducted in human fibroblasts (MRC-5 cells) and murine brain microglia (BV-2 cells) reveal a comparatively safer behavior over related biobased nanomaterials. However, a strong inflammatory response was observed when BV-2 cells were cultured in the presence of colloidal ChNFs. These novel cytotoxicity and inflammatory studies shed light on the potential of fungal ChNFs for biomedical applications.

Immobilization of Papain in Chitosan Membranes as a Potential Alternative for Skin Wounds

Papain (an enzyme from the latex of Carica papaya) is an interesting natural bioactive macromolecule used as therapeutic alternative for wound healing due to debridement action in devitalized or necrotic tissues. However, its use in high doses can induce potential skin irritation and side effects. In this study, experiments explored the ability of chitosan membrane to immobilize papain, consequently improving enzymatic activity and controlling enzyme release. Papain-loading capacity was tested via experiments of force microscopy (AFM), scanning electron microscopy (SEM-FEG), and X-ray diffraction analyses. Fourier transform infrared spectroscopy and thermal analyses assessed the enzyme interactions with the copolymer. The investigation of the feasibility of membranes included pH on the surface, elasticity, and breaking strength measurements. The surface wettability and swelling capacity of different formulations revealed the best formulation for in vitro papain release experiments. The membranes had a transparent, rough, crystalline characteristic, which was homogeneous with the membrane within the neutrality. The immobilization of papain in the chitosan membrane resulted in a decrease in the vibration band characteristic of pure papain, suggesting a displacement in the vibration bands in the FTIR spectrum. The presence of papain decreased hydrophobicity on the surface of the membrane and disturbed the membrane's ability to swell. Chitosan membranes containing papain 2.5% (0.04 g) and 5.0% (0.08 g) preserved feasible properties and improved the enzymatic activity compared (0.87 ± 0.12 AU/mg and 1.59 ± 0.10 AU/mg) with a free papain sample (0.0042 ± 0.001 AU/mg). Concentrations of over 10% (0.16 g) led to phase separation into membranes. Chitosan membranes exhibited a slow papain release behavior adjusted via the Higushi model. The experimental achievements suggest a novel and promising method for the enhancement of papain. The results indicate the potential for prolonged bioactivity for use on wounds.

Ionic liquids revolutionizing biomedicine: recent advances and emerging opportunities

Ionic liquids (ILs), due to their inherent structural tunability, outstanding miscibility behavior, and excellent electrochemical properties, have attracted significant research attention in the biomedical field. As the application of ILs in biomedicine is a rapidly emerging field, there is still a need for systematic analyses and summaries to further advance their development. This review presents a comprehensive survey on the utilization of ILs in the biomedical field. It specifically emphasizes the diverse structures and properties of ILs with their relevance in various biomedical applications. Subsequently, we summarize the mechanisms of ILs as potential drug candidates, exploring their effects on various organisms ranging from cell membranes to organelles, proteins, and nucleic acids. Furthermore, the application of ILs as extractants and catalysts in pharmaceutical engineering is introduced. In addition, we thoroughly review and analyze the applications of ILs in disease diagnosis and delivery systems. By offering an extensive analysis of recent research, our objective is to inspire new ideas and pathways for the design of innovative biomedical technologies based on ILs.

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.

Structure and Properties of Cellulose/Mycelium Biocomposites

The current environmental problems require the use of low-energy, environmentally friendly methods and nature-like technologies for the creation of materials. In this work, we aim to study the possibility of the direct biotransformation of fibrillar cellulose by fungi through obtaining a cellulose/mycelium-based biocomposite. The cellulose micro- and nanofibrils were used as the main carbon sources in the solid-phase cultivation of basidiomycete Trametes hirsuta. The cellulose fibrils in this process act as a template for growing mycelium with the formation of well-developed net structure. The biotransformation dynamics of cellulose fibrils were studied with the help of scanning electron microscopy. The appearance of nitrogen in the structure of formed fibers was revealed by elemental analysis and FTIR-spectroscopy. The fibers diameters were estimated based on micrograph analysis and the laser diffraction method. It was shown that the diameter of cellulose fibrils can be tuned by fungi through obtaining cellulose-based mycelium fibers with a narrower diameter-size distribution as compared to the pristine cellulose fibrils. The morphology of the resulting mycelium differed when the micro or nanofibrils were used as a substrate.

Synergistic performance of collagen-g-chitosan-glucan fiber biohybrid scaffold with tunable properties

Hybrid biocomposite scaffolds (HBS) that serve as a carrier for cell proliferation and differentiation are increasingly used for tissue regeneration. 3D hybrid scaffold based on collagen-grafted-chitosan-glucan fiber (CO-g-CGF-HBS) was prepared by freeze-drying technique. The swelling percentage, hydrolytic stability, and modulus of elasticity of HBS were enhanced after the chemical modification of CO with CGF. Pore size and porosity of HBS were decreased with an increased CGF ratio. HBS exhibits a higher reduction rate against different types of bacteria compared with a control sample. Thus, chemical modification of CO with different ratios of CGF significantly improved the physicochemical, antibacterial properties of HBS.

Physicochemical characterization, adsorption function and prebiotic effect of chitin-glucan complex from mushroom Coprinus comatus

Chitin-glucan complex (CGC) is a novel insoluble dietary fiber with multiple physiological activities. In this work, CGC was extracted from the fruiting body of Coprinus comatus and its physicochemical properties and prebiotic effects were investigated. The results indicated that CGC consisted of glucosamine and glucose in a molar ratio of 67: 33 with degree of acetylation of 61.91% and crystallinity index of 25.40%. The maximum degradation temperature was determined to be 307.52 °C, and a woven fibrous structure was observed by scanning electron microscopy. CGC exhibited higher oil-holding capacity, water-holding capacity and nitrite ion adsorption capacity than commercial chitin, and showed potential prebiotic effects. Compared with control and commercial chitin, CGC significantly (P < 0.05) increased the concentration of propionic and butyric acids. These results suggested that CGC from C. comatus was promising to be an alternative source of CGC products and used as a bioactive ingredient in functional foods.

Chitin-Glucan Complex Hydrogels: Optimization of Gel Formation and Demonstration of Drug Loading and Release Ability

Chitin-glucan complex (CGC) hydrogels were fabricated through a freeze–thaw procedure for biopolymer dissolution in NaOH 5 mol/L, followed by a dialysis step to promote gelation. Compared to a previously reported methodology that included four freeze–thaw cycles, reducing the number of cycles to one had no significant impact on the hydrogels’ formation, as well as reducing the total freezing time from 48 to 18 h. The optimized CGC hydrogels exhibited a high and nearly spontaneous swelling ratio (2528 ± 68%) and a water retention capacity of 55 ± 3%, after 2 h incubation in water, at 37 °C. Upon loading with caffeine as a model drug, an enhancement of the mechanical and rheological properties of the hydrogels was achieved. In particular, the compressive modulus was improved from 23.0 ± 0.89 to 120.0 ± 61.64 kPa and the storage modulus increased from 149.9 ± 9.8 to 315.0 ± 76.7 kPa. Although the release profile of caffeine was similar in PBS and NaCl 0.9% solutions, the release rate was influenced by the solutions’ pH and ionic strength, being faster in the NaCl solution. These results highlight the potential of CGC based hydrogels as promising structures to be used as drug delivery devices in biomedical applications.

Analysis of clinical trials on biomaterial and therapeutic applications of chitosan: A review

Chitosan is a modified natural carbohydrate polymer derived from chitin that occurs in many natural sources. It has a diverse range of applications in medical and pharmaceutical sciences. Its primary and permitted use is biomaterial in medical devices. Chitosan and its derivatives also find utility in pharmaceuticals as an excipient, drug carrier, or therapeutic agent. The USFDA has approved chitosan usage as a biomaterial but not for pharmaceutical use, primarily because of the concerns over its source, purity, and immunogenicity. A large number of clinical studies are underway on chitosan-based materials/ products because of their diverse applications. Herein, we analyze clinical studies to understand their clinical usage portfolio. Our analysis shows that >100 clinical studies are underway to investigate the safety/efficacy of chitosan or its biomaterials/ nanoparticles, comprising ~95% interventional and ~ 5% observational studies. The regulatory considerations that limit the use of chitosan in pharmaceuticals are also deliberated. TEASER: Clinical Trials of Chitosan.

Characterization of chitin-glucan complex from Tremella fuciformis fermentation residue and evaluation of its antibacterial performance

Submerged fermentation of fungi is an efficient way to obtain extracellular polysaccharides, however, in this process, excess discarded biomass is produced. In this study, Tremella fuciformis mycelia were reused as the raw material to isolate a novel fungal chitin-glucan complex (CGC-TFM) using alkaline extraction. Characteristic analysis revealed that the CGC-TFM consisted of glucosamine/acetylglucosamine and glucose (GlcN:Glc = 26:74 mol%), indicating a reference to the β polymorphism of chitin-glucan complex, with the molecular weight and crystallinity index of 256 ± 3.0 kDa and 54.25 ± 1.04%, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, nuclear magnetic resonance, and scanning electron microscopy analyses confirmed that the chitin portion of the CGC-TFM exhibited a typical β configuration and N-acetylation degree of 70.52 ± 2.09%. Furthermore, the CGC-TFM exhibited good thermal stability and effective Escherichia coli inhibition ability, indicating that it could be applied as a potential food packaging material.

Recent advances in ionic liquids and nanotechnology for drug delivery

In drug discovery and drug development, it is estimated that around 40% of commercialized and 90% of under-study drugs have inadequate pharmaceutical properties, severely impairing its therapeutic efficacy. Thus, there is a strong demand to find strategies to enhance the delivery of such drugs. Ionic liquids are a novel class of liquids composed of a combination of organic salts that are of particular interest alone or in combination with drug delivery systems. This review is focused on the recent efforts using ionic liquids in drug solubility, formulation and drug delivery with specific emphasis on nanotechnology. The latest developments using hybrid delivery systems obtained upon the combination of drug delivery systems and ionic liquids will also be addressed.

Regeneration behavior of chitosan from ionic liquid using water and alcohols as anti-solvents

While ionic liquids (ILs) have been considered as effective and "green" solvents for biopolymer processing, regeneration of IL-dissolved biopolymers could largely impact biopolymer structure and properties. This study indicates that the reconstitution of chitosan structure during regeneration from 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) depends on anti-solvent (water, methanol or ethanol) largely. Irrespective of anti-solvent, the chitosan chemical structure was not varied by dissolution or regeneration. With water, the regenerated chitosan had the highest crystallinity index of 54.18%, followed by those with methanol (35.07%) and ethanol (25.65%). Water as an anti-solvent could promote chitosan chain rearrangement, leading to the formation of an ordered aggregated structure and crystallites. Density functional theory (DFT) simulation indicates that the number of hydrogen bonds formed between anti-solvents and [Emim][OAc] was in the order of water > methanol > ethanol. With water used for regeneration, the aggregation and rearrangement of chitosan chains occurred more easily.