Over the past decade, reckless usage of synthetic pesticides and fertilizers in agriculture has made the environment and human health progressively vulnerable. This setting leads to the pursuit of ...other environmentally friendly interventions. Amongst the suggested solutions, the use of chitin and chitosan came about, whether alone or in combination with endophytic bacterial strains. In the framework of this research, we reported an assortment of studies on the physico-chemical properties and potential applications in the agricultural field of two biopolymers extracted from shrimp shells (chitin and chitosan), in addition to their uses as biofertilizers and biostimulators in combination with bacterial strains of the genus
sp. (having biochemical and enzymatic properties).
Chitosan (CS) is a carbohydrate biopolymer, which has been known as a biological material in promoting the healing process of soft and hard connective tissues. It is biocompatible, biodegradable, ...bioactive, non-toxic, non-expensive and non-immunogenic, with antibacterial capability. Additionally, the capacity of forming complexes with other anionic biomaterials and molecules offers CS the characteristics to be used in biomedical applications. Therefore, this natural polysaccharide has widely been used as a wound dressing and in bone and cartilage regeneration because of these considerable properties. However, some studies have showed limited value in application of CS in tissue regeneration. It has been used alone or in combination with other biopolymers, bioceramics, or promotive growth factors to enhance regeneration of the soft and hard connective tissues. This study has reviewed various forms of CS including hydrogels, sponges, films, and nanofiber membranes. The role of CS alone or in combined form with other materials has also been reviewed in healing and regeneration of the cutaneous, cartilage and bone wounds. In addition, the present study has attempted to clarify the controversies and conflicts regarding effectiveness of CS in the healing process.
•O-amine functionalized chitosan has been synthesized and characterized.•Antibacterial and antioxidative properties were significantly improved.•Thermal stability was enhanced with the incorporation ...of cinnamaldehyde.
Cinnamaldehyde was immobilized to O-amine functionalized chitosan via a coupling reaction. Fourier transform infrared spectroscopy confirmed N-cinnamyl substitution. Wetting analyses demonstrate more hydrophobicity in the N-cinnamyl substituted O-amine functionalized chitosan compared to chitosan or unsubstituted O-amine functionalized chitosan. Thermal gravimetric analysis and differential scanning calorimetry demonstrates that the prepared N-cinnamyl substituted O-amine functionalized chitosan exhibits higher thermostability than unmodified chitosan at temperatures in which polysaccharides are commonly stored and utilised. The N-cinnamyl substituted O-amine functionalized chitosan, against four different bacteria strains two gram-positive (Staphylococcus aureus and Bacillus cereus) and two gram-negative (Escherichia coli and Pseudomonas aeruginosa), displays promotion of inhibition activity against these bacterial strains. Finally, the antioxidative activity of the N-cinnamyl substituted O-amine functionalized chitosan was compared with those activities of chitosan and O-amine functionalized chitosan. This was evaluated by uninhibited and inhibited hyaluronan degradation and ABTS assay. The N-cinnamyl substituted O-amine functionalized chitosan shows a lower activity towards donating a hydrogen radical compared to chitosan or O-amine functionalized chitosan. On the other hand, the N-cinnamyl substituted O-amine functionalized chitosan exhibited a higher ability to scavenge the ABTS+ cation radical compared to chitosan and O-amine functionalized chitosan.
In this study, blended films from poly(vinyl alcohol) (PVA) containing chitosan (CS) were prepared via a simple solution casting and electrospraying method. The structures of the PVA-CS films were ...characterized by Fourier-transform infrared spectroscopy. The morphologies of the films were observed by scanning electron microscopy. The thermal properties of the PVA-CS films were examined by thermogravimetry. The effects of CS contents on the mechanical properties, oxygen permeability values, water vapor permeation levels, and antibacterial behaviors against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains were investigated. Compared to the pure PVA film, the PVA-CS films showed greater elongation at break, lower oxygen permeability, higher water barrier properties, and greater antibacterial activity, especially for the PVA:CS weight ratio of 75:25. The obtained results indicate the PVA-CS film may be a promising material for food packaging applications.
The chemical composition, structural features and bioactivities of chitosan derivatives were studied and reported here. Chitin and chitosan was extracted by chemical methods and yield was recorded ...35% and 41%, moisture and ash has showed 7.4, 0.73, 1.2 and 0.79% and Ca was recorded high level (590 ppm). The IR spectrum has showed NH primary and secondary amines, OH group and several sugar stretching. N-acetyl glucosamine (GlcNAc), H-2 proton of glucosamine (GlcN), Anomeric protons, H-1 GlcN (H-1D), GlcNAc (H-1A) were noticed in 1H NMR and anomeric, methyl carbon atoms in 13C NMR. Rough surface, irregular block, crystalline with cluster and porosity structure was noticed by SEM observation. Antioxidant effect has showed good and concentration depended in four antioxidant assays. The α-amylase and β-glucosidase enzyme inhibition effect of chitosan has showed promising and dose depend also anticoagulant potential. Chitosan could be used in pharmaceutical industry and tissue engineering.
•The structural features of chitosan was studied through FT-IR and NMR spectroscopy•Surface morphology and microstructures were observed by SEM analysis•Chitosan played a potential scavenging effect against major radicals in vitro assay•Chitosan are potential α-amylase and β-glucosidase inhibitors•Chitosan has showed effective anticoagulant action in APPTT and PT assay
The polysaccharide chitosan and the water soluble chitosan derivative N,N,N-trimethyl chitosan (TMC) have been widely investigated as permeation enhancers of mucosal surfaces with numerous papers ...published over the last two decades. Although both chitosan and TMC increase permeation of markers through mucosal membranes, such as the intestinal and airway epithelium as well as in in vivo models, these investigations have not led to their use in marketed drug formulations. In this review, the reported extent of the permeation enhancement and cell viability after chitosan or TMC treatment in intestinal and airway models is critically evaluated and concluded that the apparent discrepancies can be explained by differences in polymer structure, experimental conditions and in vitro models. Additionally, aspects regarding the synthesis of TMC and its structural characterization are described, focusing on new synthetic strategies implemented to reduce O-methylation. Finally recommendations are provided on how studies can be conducted to improve understanding of the structure–activity relationship and elucidate possible mechanism of action.
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•We synthesized a new glycol chitosan based photo-crosslinked thermogelling polymer.•Photo-crosslinked methacrylated hexanoyl glycol chitosan hydrogel shows good stability.•Chondrocyte can be ...encapsulate in to the hydrogel and maintained viability for a week or more.
The major limitations of typical thermogelling polymers for practical applications are low gel stability and weak mechanical properties under physiological conditions. In this study, we have synthesized a new polysaccharide-based thermogelling polymer that can be photo-crosslinked by UV irradiation to form a mechanically resilient and elastic hydrogel. Methacrylated hexanoyl glycol chitosan (M-HGC), was synthesized by a series of chemical modifications, N-hexanoylation and N-methacrylation, of glycol chitosan (GC). Various M-HGC polymers with different methacryl group contents were synthesized and their thermogelling and photo-crosslinkable properties were evaluated. The M-HGCs demonstrated a thermo-reversible sol–gel transition behavior in aqueous solutions. The thermally-induced hydrogels could be chemically crosslinked by UV-triggered photo-crosslinking. From the cytotoxicity studies using MTT and the live/dead assay, the M-HGC hydrogels showed non-cytotoxicity. These photo-crosslinkable thermogelling M-HGC polymers may hold great promises for various biomedical applications, such as an injectable delivery system and 3D cell culture.
•Coating table grapes with chitosan–glucose complex was investigated.•Chitosan–glucose complex coating decreased grapes decay, weight loss and respiration rate.•Chitosan–glucose complex coating ...effectively maintained fruit texture, as manifested by berry hardness, springiness, cohesiveness and chewiness.•CGC can improve the postharvest quality of table grapes and extend its shelf life.
Surface coatings and films are prospective alternatives for extending the postharvest life of fresh fruits and vegetables. In this study, freshly harvested grapes were treated with chitosan, glucose, chitosan–glucose complex (CGC), or water (control) for up to 60 days at 0°C in 95% relative humidity followed by 3 days in the air at 20°C. The results showed that coated samples were effective in terms of senescence inhibition and postharvest diseases prevention. Chitosan–glucose complex showed better effects on delaying the declines of total soluble solids, ascorbic acid and titratable acidity, decreasing decay and weight loss, suppressing respiration rate, inducing POD and SOD activities, in comparison with pure chitosan or glucose. In addition, CGC coating treatment ensured better berry texture and higher sensory scores, compared with those treated with chitosan or glucose alone. The results indicated that CGC may be a promising strategy for improving the postharvest quality and extending the shelf life of table grapes.
Raw chitin nanofibers (CNF) through an 8-min high-power sonication process were successfully prepared. Well-preserved nanofibers with diameters of 50–100 nm and lengths of 3–10 μm were observed by ...atomic force microscopy. The high aspect ratio induced strong entanglement under high shear rates, leading to a typical nanofiber four-region shear-thinning behavior. These native chitin nanofibers were incorporated into chitosan film-forming solutions at different concentrations. FTIR results indicated intermolecular hydrogen bonds between CS and CNF. Tensile strength was significantly enhanced with the inclusion of CNF, with the highest stress at 30% CNF incorporation. Elongation at break increased up to 35% with 10% CNF concentration, gradually decreasing with higher CNF content. CS with 20% addition of CNF content was chosen for curcumin addition considering the high mechanical performance and low grammage value. Oxygen transmission rate reduced slowly with increasing CNF concentration, and a significant drop by about 90% was observed upon curcumin inclusion. UV blocking performance and antioxidant ability were drastically improved after curcumin inclusion. The utilization of raw CNF as a film reinforcement nanofiller offers several advantages, including ease of preparation, higher aspect ratio, longer length, and superior mechanical performance. CNF-reinforced chitosan films emerge as potent candidates for functional food packaging materials.
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•Raw chitin nanofiber with a high aspect ratio was prepared by ultrasonication.•A typical nanofiber four-region shear thinning behavior was observed on raw chitin nanofiber suspension.•Raw chitin nanofiber significantly improved the elongation at break and tensile strength for chitosan films.•The incorporation of curcumin enhanced the chitosan/chitin nanofiber film antioxidant and oxygen barrier ability.
Chitosan, the N-deacetylated derivative of chitin, is a potential biopolysaccharide owing to its specific structure and properties. In this paper, we report on the synthesis of 24 new chitosan ...derivatives, N-alkyl chitosans (NAC) and N-benzyl chitosans (NBC), that are soluble in dilute aqueous acetic acid. The different derivatives were synthesized by reductive amination and analyzed by 1H NMR spectroscopy. A high degree of substitution (DS) was obtained with N-(butyl)chitosan (DS 0.36) at a 1:1 mole ratio for NAC derivatives and N-(2,4-dichlorobenzyl)chitosan (DS 0.52) for NBC derivatives. Their insecticidal and fungicidal activities were tested against larvae of the cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), the grey mould Botrytis cinerea Pers (Leotiales: Sclerotiniaceae) and the rice leaf blast Pyricularia grisea Cavara (Teleomorph: Magnaporthe grisea (Hebert) Barr). The oral feeding bioassay indicated that all the derivatives had significant insecticidal activity at 5 g kg(-1) in artificial diet. The most active was N-(2-chloro-6-fluorobenzyl)chitosan, which caused 100% mortality at 0.625 g kg(-1), with an estimated LC50 of 0.32 g kg(-1). Treated larvae ceased feeding after 2-3 days; the mechanism of action remains unknown. In a radial hyphal growth bioassay with both plant pathogens, all derivatives showed a higher fungicidal action than chitosan. N-Dodecylchitosan, N-(p-isopropylbenzyl)chitosan and N-(2,6-dichlorobenzyl)chitosan were the most active against B cinerea, with EC50 values of 0.57, 0.57 and 0.52 g litre(-1), respectively. Against P grisea, N-(m-nitrobenzyl)chitosan was the most active, with 77% inhibition at 5 g litre(-1). The effect of different substitutions is discussed in relation to insecticidal and fungicidal activity.
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