Structure Of Chitosan Research Articles

Active Films and Coatings Based on Propolis Extract and Chitosan: Physicochemical Characterization and Potential Application in Refrigerated Shrimps (Litopenaeus vannamei)

AbstractMelanosis is a bio‐chemical reaction that reduces the acceptability of refrigerated shrimps. The current research aims to produce and characterize chitosan‐based coatings added of propolis extract (PE), as well as to investigate the potential application of these materials to control the melanosis of refrigerated shrimps during storage (9 days). Shrimps are coated with chitosan solutions content different PE concentrations (0%, 5%, 10%, and 20%). Uncoated shrimps and shrimps coated with sodium metabisulfite are also investigated. The incorporation of PE modifies the crystalline structure of chitosan, reducing the water contact angle, and thermal stability of films. Shrimps coated with chitosan‐based solutions containing 20% of PE display lower dark points in the cephalothorax and joints region, as well as better weight retention during storage. These results suggest that chitosan‐based coatings containing PE can be an eco‐friendly alternative to substitute sodium metabisulfite in refrigerated shrimps.

A stable electrochemical chiral interface based on graphene-chitosan composites for tyrosine enantiomers recognition

The effective synthesis of graphene oxide (GO) modified with chitosan (CS) via covalent bond exhibited the properties of a wide surface area and high chiral selectivity. The successful synthesis of composites was characterized by the FTIR, XPS and electrochemical methods. Then a novel chiral electrochemical sensor based on chitosan covalently binding with the graphene (RGO/CS) was fabricated for discrimination of tyrosine (Tyr) enantiomers. The results showed that the chiral selector CS preferably combined with D-Tyr rather than L-Tyr, which was attributed to the favorability of host–guest interactions between CS and Tyr enantiomers. In comparison, recognition efficiency was significantly improved after CS was grafted onto RGO, which might be attributed to the formation of intermolecular forces between Tyr enantiomers and CS. Furthermore, the structure of CS could play an important role in enantioselective discrimination. The as-synthesized material was successfully exploited for the recognition of Tyrosine enantiomers, indicating that the developed sensor has wide application prospects.

Effective Endotoxin Removal from Chitosan That Preserves Chemical Structure and Improves Compatibility with Immune Cells.

Chitosan is one of the most researched biopolymers for healthcare applications, however, being a naturally derived polymer, it is susceptible to endotoxin contamination, which elicits pro-inflammatory responses, skewing chitosan's performance and leading to inaccurate conclusions. It is therefore critical that endotoxins are quantified and removed for in vivo use. Here, heat and mild NaOH treatment are investigated as facile endotoxin removal methods from chitosan. Both treatments effectively removed endotoxin to below the FDA limit for medical devices (<0.5 EU/mL). However, in co-culture with peripheral blood mononuclear cells (PBMCs), only NaOH-treated chitosan prevented TNF-α production. While endotoxin removal is the principal task, the preservation of chitosan's structure is vital for the synthesis and lysozyme degradation of chitosan-based hydrogels. The chemical properties of NaOH-treated chitosan (by FTIR-ATR) were significantly similar to its native composition, whereas the heat-treated chitosan evidenced macroscopic chemical and physical changes associated with the Maillard reaction, deeming this treatment unsuitable for further applications. Degradation studies conducted with lysozyme demonstrated that the degradation rates of native and NaOH-treated chitosan-genipin hydrogels were similar. In vitro co-culture studies showed that NaOH hydrogels did not negatively affect the cell viability of monocyte-derived dendritic cells (moDCs), nor induce phenotypical maturation or pro-inflammatory cytokine release.

Structure and Antibacterial Activity of Chitosan from the American Cockroach, the German Cockroach and the Mealworm Beetle.

Owing to chitosan properties such as biocompatibility and antimicrobial activities, and several applications in biomedical field, some physicochemical and anti-bacterial properties, and the level of chitosan from three species of American cockroach, Periplaneta americana (Dictyoptera: Blattidae), the German cockroach, Blattella germanica (Dictyoptera: Ectobiidae) and the Mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae) were investigated. The cuticle of adults derived from specimens was dried and grounded. The powders were demineralized as well as deproteinized after deacetylation via NaOH. At last, the chitosan yields from insects were studied for antibacterial activity on Gram-positive bacteria (Proteus mirabilis, Klebsiella pneumoniae), and Gram-negative bacteria (Enterococcus faecalis and Staphylococcus epidermidis). The Fourier transform infrared spectroscopy (FTIR) was used to analyze the chitosan composition. The chitosan ratios of the American and German cockroaches and the mealworm beetle were 5.80, 2.95, and 1.70% per 3 g of the dried bodies respectively. The chitin DD's for the American cockroach, the German cockroach and the mealworm beetle were 36.8%, 31.5% and 27.3%, respectively. The bactericidal activity of chitosan obtained from the American cockroach at a concentration of 1% had the greatest effect on P. mirabilis compared to other concentrations, while chitosan obtained from the German cockroach at a concentration of 0.01% had the greatest effect on K. pneumoniae compared to other concentrations. According to the results, the anti-bacterial influence of the chitosan is based upon the insect species and chitosan concentration. Probably, the variation relates to the changes in the chitin structure among the three insect species.

Chitosan-Bead-Encapsulated Polystyrene Sulfonate for Adsorption of Methylene Blue and Regeneration Studies: Batch and Continuous Approaches.

Textile industrialization causes water pollution due to the discharge of industrial effluents into the environment. To reduce the impact of industrial effluent, it must be treated in wastewater treatment plants before discharge into rivers. Among all wastewater treatment approaches, the adsorption process is one method to remove pollutants from wastewater, but it has some limitations in term of reusability and ionic selective adsorption properties. In this study, we prepared cationic poly (styrene sulfonate) (PSS)-incorporated anionic chitosan beads synthesized using the oil-water emulsion coagulation method. The produced beads were characterized using FESEM and FTIR analysis. In batch adsorption studies, the PSS-incorporated chitosan beads exhibited monolayer adsorption processes, that is, exothermic processes that occur spontaneously at low temperatures, which were analyzed based on the adsorption isotherms, adsorption kinetics, and thermodynamics model fittings. The presence of PSS enables cationic methylene blue dye to adsorb to the anionic chitosan structure via electrostatic interaction between the sulfonic group and the dye molecule. The maximum adsorption capacity of PSS-incorporated chitosan beads achieved 42.21 mg/g, as calculated from the Langmuir adsorption isotherm. Finally, the PSS-incorporated chitosan beads demonstrated good regeneration with different types of reagents, especially using sodium hydroxide as a regeneration reagent. With the use of sodium hydroxide regeneration of this adsorbent material, a continuous adsorption setup also demonstrated that PSS-incorporated chitosan beads can be reused for methylene blue adsorption for up to three cycle processes.

Chitosan-Based Biomaterials for Tissue Regeneration.

Chitosan is a chitin-derived biopolymer that has shown great potential for tissue regeneration and controlled drug delivery. It has numerous qualities that make it attractive for biomedical applications such as biocompatibility, low toxicity, broad-spectrum antimicrobial activity, and many others. Importantly, chitosan can be fabricated into a variety of structures including nanoparticles, scaffolds, hydrogels, and membranes, which can be tailored to deliver a desirable outcome. Composite chitosan-based biomaterials have been demonstrated to stimulate in vivo regeneration and the repair of various tissues and organs, including but not limited to, bone, cartilage, dental, skin, nerve, cardiac, and other tissues. Specifically, de novo tissue formation, resident stem cell differentiation, and extracellular matrix reconstruction were observed in multiple preclinical models of different tissue injuries upon treatment with chitosan-based formulations. Moreover, chitosan structures have been proven to be efficient carriers for medications, genes, and bioactive compounds since they can maintain the sustained release of these therapeutics. In this review, we discuss the most recently published applications of chitosan-based biomaterials for different tissue and organ regeneration as well as the delivery of various therapeutics.

Proteases and microwave treatment on the quality of chitin and chitosan produced from white shrimp (Penaeus vannamei)

AbstractThe aim of this study was to extract chitin and chitosan from shrimp shells by neutral protease‐assisted microwave multiple heating (one, two, three, and four) treatment. The structure and physicochemical properties of chitosan were characterized by scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FTIR). The dielectric properties of chitosan acetate solution were determined by using a PNA‐L network analyzer, and the correlation between chitosan deacetylation degree and dielectric loss was further analyzed. The results show that the degree of deacetylation of chitosan increased from 84.9% to 90.8% with the increase in the number of microwave heating treatments. Furthermore, the chitosan prepared by multiple microwave heating was smoother. The dielectric constant of chitosan solution gradually decreases with the increase of frequency, and the dielectric loss first decreases and then increases. In addition, the dielectric loss of the chitosan solution increased with the degree of deacetylation of chitosan at 2450 MHz (R2 &gt; 0.99). Therefore, enzyme‐assisted microwave extraction of chitosan can be used to obtain high‐quality chitosan under the condition of increasing the number of heating treatments.

The preparation of a chitosan-based novel fluorescent macromolecular probe and its application in the detection of hypochlorite

In this paper, a novel fluorescent probe with high sensitivity and selectivity to hypochlorite (ClO−) was prepared by an acylation reaction and Suzuki coupling reaction. The probe takes chitosan and 4-bromo-1, 8-naphthalene as raw materials and, a fluorescent test paper for ClO− detection in water was prepared using this new probe. The structure of this new fluorescent chitosan was analyzed by Fourier Transform infrared spectroscopy, nuclear magnetic resonance, an energy dispersive X-ray spectrometer, a scanning electron microscope, and an X-ray diffractometer. The properties of this probe were characterized by a thermogravimetric analyzer, ultraviolet–vis spectrophotometer, and fluorescence spectrophotometer. The results show that the expected probe is successfully synthesized and the probe has good thermal stability. Furthermore, the fluorescence probe can detect ClO− quickly and has a good selectivity and anti-interference. When ClO− was added within 8 min, the test paper showed a noticeable change from yellow to blue.

Chitosan Based Materials in Cosmetic Applications: A Review

This review provides a report on the properties and recent advances in the application of chitosan and chitosan-based materials in cosmetics. Chitosan is a polysaccharide that can be obtained from chitin via the deacetylation process. Chitin most commonly is extracted from cell walls in fungi and the exoskeletons of arthropods, such as crustaceans and insects. Chitosan has attracted significant academic interest, as well as the attention of the cosmetic industry, due to its interesting properties, which include being a natural humectant and moisturizer for the skin and a rheology modifier. This review paper covers the structure of chitosan, the sources of chitosan used in the cosmetic industry, and the role played by this polysaccharide in cosmetics. Future aspects regarding applications of chitosan-based materials in cosmetics are also mentioned.

Performance tuning of chitosan-based membranes by protonated 2-Pyrrolidone-5-carboxylic acid-sulfolane DES for effective water/ethanol separation by pervaporation

Today, the applicability of deep eutectic solvents (DES) in various fields, including membrane science and technology, is extensively investigated. In pioneering works, we have implemented different DES as a component of chitosan (CS)-based flat membranes for pervaporation (PV) separation. Herein, we present a new protonated (by sulphuric acid) 2-Pyrrolidone-5-carboxylic acid: sulfolane DES, as a green additive for its chemical blending and thus study its effect in CS structure. The resultant flat CS-based membranes have been characterized and tested for their ability in separating water molecules from ethanolic mixtures (10 wt% water in ethanol) using PV. Experiments revealed a progressive increase in total permeation along with increase of temperature in the range of 20–50 °C. Simultaneously, the value of separation factor was reduced. The maximum permeation (approximately 0.44 kg m−2 h−1) was observed for the highest experimental temperature, in which water was the main component, while the highest separation factor (approximately 518) was observed for lowest operating temperature. It was confirmed that application of selected DES allowed to improve the permeation rates in comparison with the bare CS membrane. As a perspective, such membranes could be tested for another hydrophilic pervaporation applications for the removal of polar compounds – with high applicability in biorefineries.

King crab gills as a new source of chitin/chitosan and protein hydrolysates

This is the first report on the physicochemical properties of chitin obtained from gills of the king crab Paralithodes camtschaticus. In the present study, we investigated the chemical composition of red king crab gills and considered methods of its complex processing to obtain chitin and enzymatic protein hydrolysates. The gills contained approximately 21 % chitin in terms of dry matter. For the first time, the gills of the king crab were investigated as a source of chitin and chitosan.Chitin was isolated from crab gills using chemical and enzymatic methods. The physicochemical properties of chitin and chitosan from the gills were investigated. By performing infrared spectroscopy and X-ray phase analyses, the chitin present in the gills was established to be α-chitin. The physical and chemical properties (degree of deacetylation, molecular weight and crystal structure) of gill chitin and chitosan were absolutely similar to those of crab shell.Crab gills can be used as an additional source of chitin in the integrated processing of king crabs. The yield of chitin from the gills is up to 45 % of the yield of chitin from the crab carapace.

Copper nanoparticles embedded fungal chitosan as a rational and sustainable bionanozyme with robust laccase activity for catalytic oxidation of phenolic pollutants.

Despite their potential for oxidation of persistent environmental pollutants, the development of rational and sustainable laccase nanozymes with efficient catalytic performance remains a challenge. Herein, fungal-produced chitosan-copper (CsCu) is proposed as a rational and sustainable bionanozyme with intrinsic laccase activity. The CsCu nanozyme was prepared by in situ reduction of copper on chitosan extracted from Irpex sp. isolate AWK2 a native fungus, from traditional fermented foods, yielding a low molecular weight chitosan with a 70% degree of deacetylation. Characterizations of the nanozyme using SEM-EDX, XRD, and XPS confirmed the presence of a multi-oxidation state copper on the chitosan matrix which is consistent with the composition of natural laccase. The laccase memetic activity was investigated using 2,4-DP as a substrate which oxidized to form a reddish-pink color with 4-AP (λmax = 510 nm). The CsCu nanozyme showed 38% higher laccase activity than the pristine Cu NPs at pH 9, indicating enhanced activity in the presence of chitosan structure. Further, CsCu showed significant stability in harsh conditions and exhibited a lower Km (0.26 mM) which is competitive with that reported for natural laccase. Notably, the nanozyme converted 92% of different phenolic substrates in 5 h, signifying a robust performance for environmental remediation purposes.

The effect of different molecular weight chitosan on the physical and mechanical properties of plasticized films

Packaging materials based on biodegradable polymers are a viable alternative to replacing conventional plastic packaging of fossil origin. The main two factors affecting functionality and performance are the molecular weight and the type of plasticizer used in these materials. The goal of this research was to modify unfractionated plasticized chitosan films to improve the physical and mechanical characteristics of the original unfractionated chitosan films. Chitosan extracted from local shrimp shells was zone-refined to produce five distinct chitosan fractions with molecular weights ranging from 1.089×105 to 5.605×105 g/mole. The unfractionated and fractionated chitosan films plasticized with 1:3 poly(vinyl alcohol) and 2:1 maleic acid were prepared by casting from their 2% acetic acid solutions. They were examined by FT-IR and were found to be comparable to the native chitosan spectrum, indicating that the primary backbone of the chitosan structure was unaltered. Therefore, the effects of molecular weight fractions and the type of plasticizer on the physical and mechanical properties were investigated. Examining the films’ surface topography by atomic force microscopy revealed that increasing the molecular weight of chitosan fractions from 2.702×105 to 5.605×105 g/mole affects the surface morphology of the chitosan: poly(vinyl alcohol) (1:3) film. This was accompanied by an increase in the surface roughness of the resulting film from 0.953 to 2.82, and for chitosan: maleic acid from 0.509 to 1.62. It was found that the tensile strength and Young’s modulus of the cast films decreased and the percent elongation at break of the plasticized fractionated chitosan films was increased, implying that less stiff films were obtained with fractionated chitosan. The outcome of this work suggests that the biodegradable fractionated chitosan blend film is a promising packaging material and that poly(vinyl alcohol) is the most suitable plasticizer for this formulation.

Comparative Study of Sonophotocatalytic, Photocatalytic, and Catalytic Activities of Magnesium and Chitosan-Doped Tin Oxide Quantum Dots.

The present study demonstrates the hydrothermal synthesis of SnO2 quantum dots (QDs) doped with different concentrations (2, 4 wt %) of magnesium (Mg) and a fixed amount of chitosan (CS). The obtained samples were investigated through a number of characterizations for optical analysis, elemental composition, crystal structure, functional group presence, interlayer spacing, and surface morphology. The XRD spectrum revealed the tetragonal structure of SnO2 with no significant variations occurring upon the addition of CS and Mg. The crystallite size of QDs was reduced by incorporation of dopants. The optical absorption spectra revealed a red shift, assigned to the reduction of the band gap energy upon doping. TEM analysis proved that the few nanorod-like structures of CS overlapped with SnO2 QDs, and agglomeration was observed upon Mg doping. The incorporation of dopants little enhanced the d-spacing of SnO2 QDs. Moreover, the synthesized nanocatalyst was utilized to calculate the degradation percentage of methylene blue (MB) dye. Afterward, a comparative analysis of catalytic activity, photocatalytic activity, and sonophotocatalytic activity was carried out. Notably, 4% Mg/CS-doped QDs showed maximum sonophotocatalytic degradation of MB in basic medium compared to other activities. Lastly, the prepared nanocatalyst was found to be efficient for dye degradation in any environment and inexpensive.

Antioxidant packaging films developed based on chitosan grafted with different catechins: Characterization and application in retarding corn oil oxidation

Four catechins including (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG) were conjugated onto chitosan (CS) molecules via ascorbate radical mediated reaction, producing EC-g-CS, ECG-g-CS, EGC-g-CS and EGCG-g-CS. The four catechin-g-CSs were individually blended with CS to develop food packaging films. The structure, physicochemical properties and antioxidant activity of four catechin-g-CSs as well as their corresponding packaging films were compared. Results showed the total phenol content differed in four catechin-g-CSs, where ECG-g-CS and EGCG-g-CS had higher total phenol contents than EC-g-CS and EGC-g-CS. Four catechin-g-CSs showed the characteristic UV–vis, infrared and nuclear magnetic resonance signals of catechins, revealing the successful conjugation of CS with catechins. Antioxidant activity of CS was elevated by catechins to different degrees, with EGCG-g-CS having the highest antioxidant activity. The developed CS/catechin-g-CSs films showed larger thickness, water solubility, tensile strength, elongation at break, thermal stability and antioxidant activity but lower light transmittance, water contact angle, water vapor and oxygen permeability in comparison with CS film. Meanwhile, CS/catechin-g-CSs films had good anti-permeability against corn oil and effectively retarded the increase of thiobarbituric acid reactive substance and peroxide value levels during oil storage. Findings showed CS/catechin-g-CSs films were ideal antioxidant packaging materials for edible oils. • Four catechins were individually grafted onto chitosan (CS) molecules. • Catechins changed the structure and antioxidant activity of CS. • Catechin-g-CSs increased the barrier, mechanical and antioxidant properties of film. • Film containing catechin-g-CSs retarded the oxidation of corn oil. • Film containing (−)-epicatechin gallate-g-CS had the best functionality.

Structure and thermal properties of chitin and chitosan from various sources

The structural and thermal properties of chitin and chitosan isolated from different sources (Artemia sp.cysts (from the Aral Sea) and Silkworm pupae (Bombyx mori)) were studied by using FTIR, XRD, and DSC. It is shown, that the chitin and chitosan samples from different sources have a similar structure, however, depending on the sources differ in the ratio of the phase composition. Two types of crystalline modification of the structure (α-and β-modifications) are observed for chitin isolated from Artemia sp.cysts. The chitin isolated from Bombyx mori has three polymorphs (α-, β-and γ-modifications) with orthorhombic, monoclinic and triclinic syngonies. The thermal stability of chitin and chitosan samples was also depended on sources.

Preparation and Study of Some Physical and Mechanical Properties of Plasticized Chitosan Films

Biodegradable polymer-based packaging materials are a practical replacement for traditional plastic packaging made of fossil fuels. The molecular weight and the kind of plasticizer present in these materials are the two primary variables influencing their usability and performance. This study set out to physically blend chitosan to enhance the physical and mechanical properties of chitosan cast films. A chitosan extract with a molecular weight of 2.702x105 g/mole with an 80% degree of deacetylation level was produced from the shells of local shrimp. Chitosan films plasticized with varied w/w ratios of diethylene glycol and poly(ethylene glycol) with molecular weights of 400 and 1500 g/mole were produced by casting from 2%acetic acid solutions. By using FTIR to analyze them, it was found that their spectra were compared to those of native chitosan, showing that the main backbone of the chitosan structure was unaffected. An examination of the mechanical properties of the films revealed that the results of the tensile strength measurement showed that the combination of diethylene glycol and poly(ethylene glycol) improved the mechanical properties of chitosan as films were obtained with more elasticity than unplasticized chitosan with better solubility.

Biosynthesis and Analytical Characterization of Iron Oxide Nanobiocomposite for In-Depth Adsorption Strategy for the Removal of Toxic Metals from Drinking Water.

The biosynthesis of the iron oxide nanoparticles was done using Ixoro coccinea leaf extract, followed by the fabrication of iron oxide nanobiocomposites (I-Fe3O4-NBC) using chitosan biopolymer. Furthermore, the synthesized I-Fe3O4-NPs and I-Fe3O4-NBC were characterized, and I-Fe3O4-NBC was applied to remove toxic metals (TMs: Cd, Ni, and Pb) from water. The characterization study confirmed that the nanostructure, porous, rough, crystalline structure, and different functional groups of chitosan and I-Fe3O4-NPs in I-Fe3O4-NBCs showed their feasibility for the application as excellent adsorbents for quantitative removal of TMs. The batch mode strategy as feasibility testing was done to optimize different adsorption parameters (pH, concentrations of TMs, dose of I-Fe3O4-NBC, contact time, and temperature) for maximum removal of TMs from water by Fe3O4-NBC. The maximum adsorption capacities using nanocomposites for Cd, Ni, and Pb were 66.0, 60.0, and 66.4mgg-1, respectively. The adsorption process follows the Freundlich isotherm model by I-Fe3O4-NBC to remove Cd and Ni, while the Pb may be adsorption followed by multilayer surface coverage. The proposed adsorption process was best fitted to follow pseudo-second-order kinetics and showed an exothermic, favorable, and spontaneous nature. In addition, the I-Fe3O4-NBC was applied to adsorption TMs from surface water (%recovery > 95%). Thus, it can be concluded that the proposed nanocomposite is most efficient in removing TMs from drinking water up to recommended permissible limit.

Effects of reaction environments on the structure and physicochemical properties of chitosan and its derivatives

The structural transformation of chitosan caused by reaction environment is one of the main factors affecting its functional properties. Herein, the effects of homogeneous and heterogeneous reactions on the structure and properties of chitosan were investigated. The pretreatment of reaction increased the deacetylation degree (DD) of chitosan and resulted in its degradation. In contrast, the effect of alkali dissolution process on the above characteristics was less than 8 %. In addition, the modification of functional groups and alkaline reaction environment leaded to further degradation and deacetylation of chitosan. The alkali swelling increased the specific surface area of chitosan particles, but not completely destroy its internal structure to ensure the uniformity of reaction. Interestingly, the homogeneous modification of dissolved chitosan at lower temperature reduced the degree of substitution (DS) of its derivatives but made them exhibit self-assembly properties. This study provided theoretical basis for precise preparation and application of chitosan derivatives.

Environmentally hazard and toxic exoskeletons of marine crustaceans wastes in synthesizing N-deacetylated chitin

High molecular weight chitosan was synthesized from shrimp shells. Chemical structure of chitosan was confirmed using FT-IR, XRD, TGA, and SEM analyses. Physicochemical properties of chitosan such as molecular weight (800 000 g/mol), deacetylation degree (80%), ash content (1%) indicating effectiveness of demineralization step in removing minerals, water binding capacity (4220%), and fat binding capacity (537%), were determined. FT-IR spectra exhibited characteristic joint band at 3365 cm-1 due to –OH and –NH2 regarding to the conversion of chitin acetyl group to NH2 of chitosan.