Different Molecular Weights Of Chitosan Research Articles

Characterization of insect chitosan films from Tenebrio molitor and Brachystola magna and its comparison with commercial chitosan of different molecular weights

Insects are considered as alternative sources of chitosan; however, studies about the functional film-forming properties of insect chitosan are scarce. Insect chitosan films were made from Tenebrio molitor and Brachystola magna and were compared with commercial chitosan of different molecular weights (Mw). Mechanical properties (tensile strength, TS; elastic modulus, EM; elongation at break, %E), water vapor permeability (WVP) and physicochemical properties were characterized. The film properties of both commercial and insect chitosan were affected by Mw. Commercial chitosan films showed that at lower Mw, the TS (from 59 to 48 MPa) and EM (from 1471 to 1286 MPa) decreased; whereas WVP (from 2.9 × 10−11 to 3.4 × 10−11 g m−1s−1Pa−1), % E (from 38 to 41%) and solubility (from 30 to 33%) increased. Chitosan insect films showed lower TS and EM, and higher WPV, %E and solubility than commercial films. SEM revealed that chitosan insect films had lower porosity than commercial films. FTIR and X-ray diffraction showed not difference between insect and commercial chitosan films. These results showed that T. molitor and B. magna chitosan films could be used as a packaging material in several food products.

Effects of different molecular weights of chitosan on methane production and bacterial community structure in vitro

As a new feed additive, chitosan has been shown in recent years to have a certain role in reducing methane emissions from the gastrointestinal tracts of ruminants. However, the effects of chitosan with different molecular weights on rumen fermentation, methane production and bacterial community structure are not yet clear. A basal diet without chitosan served as the control (CTL), and the treatment diets were supplemented with chitosan with different molecular weights: 1 000 (1K), 3 000 (3K), 5 000 (5K), 50 000 (5W) and 200 000 (20W) dry matter (DM). Six fermentation units per treatment were established. Gas chromatography was used to measure the concentrations of methane, H2 and volatile fatty acids (VFAs). The bacterial 16S rRNA genes were sequenced with an Illumina MiSeq platform and analysed to reveal the relative abundances of bacterial community taxa. The results showed that the propionate proportion was significantly increased by the addition of chitosan with different molecular weights (P<0.05), while methane production and the acetate proportion were significantly decreased (P<0.05). The relative abundances of Rikenellaceae_RC9_gut_group and Prevotellaceae_UCG_003 were significantly increased in the 3K chitosan group compared with the CTL group, whereas the relative abundance of Ruminococcaceae_NK4A214_group was significantly decreased (P<0.05). Correlation analyses of the relative abundances of the bacterial genera showed that Prevotella was positively related to propionate production (P<0.05). In conclusion, 3K chitosan could reduce methane production by replacing fibrolytic bacteria (Firmicutes and Fibrobacteres) with amylolytic bacteria (Bacteroidetes and Proteobacteria) in the bacterial community structure.

Impact of the molecular weight on the size of chitosan nanoparticles: characterization and its solid-state application

Chitosan nanoparticles (CSNPSs) were prepared from noncommercial chitosan of different molecular weights by the ionic gelation methodology. CSNPSs were applied in solid state (g) to observe the bacterial growth of Bacillus halotolerans MCC1, bacteria that appear in the biofilms of the desalinization membranes. Characterization of CSNPS of high (CSNP2), medium (CSNP3), and low (CSNP4) molecular weight (MW) was studied by TGA, DSC, SEM, EDX, DLS, and XRD. The effect of MW onto the formation of CSNPS was investigated as well as the effect of its application (0.01, 0.03, and 0.03 g at 24, 48, and 72 h) in the growth (%) of B. halotolerans MCC1. The results showed that the average size of CSNPS was in the range of 420–600.3 nm. CSNPS were considered amorphous and less thermally stable than the original chitosan where they were produced. Morphologically when the MW decreases, a reduction in the size of the particle was exhibited. When MW increase a reduction in the zeta potential from 45.7 to 29.9 mV was resulted. The essays to observe the growth (%) of B. halotolerans MCC1 indicated that CSNPS applied in solid state allows the growth of the bacteria; when the MW decreases, the growth of the bacteria increases. The maximum and minimum value of growth was obtained at 72 h, with the use of 0.05 g of CSNP4 (16.86%) and 0.05 g of CSNP2 (2.15%), respectively. The use of CSNPS indicates that the inhibitory effect depends on the MW as well as the doses of application.

Comparative Effects and Mechanisms of Chitosan and Its Derivatives on Hypercholesterolemia in High-Fat Diet-Fed Rats.

The present study investigated and compared the effects of different molecular weights of chitosan (high molecular weight chitosan (HC) and low molecular weight chitosan (LC)) and its derivatives (chitosan oligosaccharide (CO)) on cholesterol regulation in high-fat (HF) diet-fed rats. A diet supplementation of 5% HC, 5% LC, or 5% CO for 8 weeks showed hypocholesterolemic potential in HF diet-fed rats. Unexpectedly, a 5% CO-supplemented diet exerted hepatic damage, producing increased levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and tumor necrosis factor-alpha (TNF-α). The supplementation of HC and LC, unlike CO, significantly decreased the hepatic total cholesterol (TC) levels and increased the fecal TC levels in HF diet-fed rats. The hepatic protein expression of the peroxisome proliferator-activated receptor-α (PPARα) in the HF diet-fed rats was markedly decreased, which could be significantly reversed by both HC and LC, but not CO, supplementation. Unlike the supplementation of CO, both HC and LC supplementation could effectively reverse the HF-inhibited/induced gene expressions of the low-density lipoprotein receptor (LDLR) and cholesterol 7α-hydroxylase (CYP7A1), respectively. The upregulated intestinal acyl-CoA cholesterol acyltransferase 2 (ACAT2) protein expression in HF diet-fed rats could be reversed by HC and LC, but not CO, supplementation. Taken together, a supplementation of 5% CO in HF diet-fed rats may exert liver damage via a higher hepatic cholesterol accumulation and a higher intestinal cholesterol uptake. Both HC and LC effectively ameliorated the hypercholesterolemia and regulated cholesterol homeostasis via the activation and inhibition of hepatic (AMPKα and PPARα) and intestinal (ACAT2) cholesterol-modulators, respectively, as well as the modulation of downstream signals (LDLR and CYP7A1).

PERFORMANCE OF QUERCETIN-CHITOSAN GELS AS TOPICAL DELIVERY SYSTEMS

This study was designed to evaluate suitability of chitosan polymer as a vehicle for topical delivery system. Quercetin (QUT) is a natural flavonoid, was incorporated into the gel vehicles in a concentration of 0.5% w/v. Gels were prepared with three different concentrations and different molecular weights of chitosan. Viscosity, drug release from prepared gels, permeation of drug through skin rat and anti-inflammatory activity of the drug using carrageenan induced rat paw edema method were studied. In-vitro release characteristics of the drug from different gels were carried out using dialysis membrane in phosphate buffer, pH 5.5. The release data were treated with various kinetic principles to assess the relevant parameters. The general rank order of QUT release was F1 > F4 > F2 > F3 > F5. The results also showed that, the release of drug from the prepared gels obeyed the diffusion model (Higuchi’s equation). The results revealed an inverse correlation between the drug release percent and the polymer concentration used. The permeation of drug through skin rat was carried out. The flux of drug is independent on the viscosity of the formulae. The results also showed a significant anti-inflammatory activity on rat paw edema

Effect of different molecular weights of chitosan on the removal efficiencies of heavy metals from contaminated water

Effect of different molecular weights of chitosan on the removal efficiencies of heavy metals from contaminated water

Modification of different molecular weights of chitosan by p-Coumaric acid: Preparation, characterization and effect of molecular weight on its water solubility and antioxidant property

In this study, we modified three different molecular weights of chitosan by using p-Coumaric acid (p-CA) for enhancing their water solubility and antioxidant property. The chemical and physical properties of all native chitosan and its modified products were determined by Fourier transform spectroscopy (FTIR), ninhydrin assay, Folin-Ciocalteu reagent procedure, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), high performance of liquid chromatography (HPLC), X-ray diffraction (XRD), water solubility and antioxidant property (both DPPH assay and reducing power assay). Results showed that the water solubility and antioxidant property of modified product decreases, when molecular weight of corresponding native chitosan increases. The obtained modified product had good solubility over a wide range of pH. Thermal analysis (TGA and DSC) showed the lower thermal stability of the modified product than that of corresponding native chitosan. XRD pattern revealed that the crystallinity was less in modified product than that of respective chitosan. The enhanced partially water solubility and antioxidant property of all modified chitosan products might be a great advantage, while applied in a wide range of applications in the form antioxidant property in food, biomedical and cosmetic industry.

New bio-based phosphorylated chitosan/alginate protective coatings on aluminum alloy obtained by the LbL technique

Bio-based coatings were obtained by the layer-by-layer (LbL) technique from a native chitosan (Mw ≈ 30,000 g mol−1) or from two synthesized phosphorylated chitosan of different molecular weights (Mw ≈ 30,000 g mol−1 and Mw ≈ 250,000 g mol−1) combined with alginate and used for corrosion protection of an aluminum alloy (AA) 3003. First, the LbL growth was monitored by Fourier transform infrared spectroscopy on silicon wafers. Cross-sections of Si wafers were examined by scanning electron microscopy allowing the films thickness to be measured. With the native chitosan and in the presence of 10 bilayers, the LbL thickness was about 200 nm, whereas it was about 300 nm with the phosphorylated chitosan of low molecular weight and about 500 nm with the phosphorylated chitosan of high molecular weight. Then, the bio-based coatings were deposited on the AA3003 by the LbL technique and their protective properties were evaluated by electrochemical impedance spectroscopy (EIS) during immersion in a 0.1 M Na2SO4 solution. It was shown that the three LbL coatings improved the corrosion resistance of the AA3003. The resistance values, extracted at low frequency on the impedance diagrams were attributed to the resistance of the aluminum oxide layer (Rox). The Rox values were at least two orders of magnitude higher for the coated samples (108 Ω cm2) compared to the uncoated one (5 105 Ω cm2). There was no significant difference between the different LbL coatings, which mainly acted by decreasing the active surface area and have a limited barrier effect.

Polysaccharide-Based Hybrid Self-Healing Hydrogel Supports the Paracrine Response of Mesenchymal Stem Cells

The aim of stem cell therapy is to repair damaged tissues. Some of the challenges facing its success include cell retention and survival at the wound site. While the retention of cells has been addressed by employing scaffolds, the survival of transplanted cells in the repair tissue is however low. It is hypothesized that the observed regeneration is more a result of migration of tissue repairing cells from adjoining tissues in response to paracrine factors secreted by implanted cells than by the implanted cells per se. In this study, we report the synthesis of a self-healing hybrid hydrogel that is injectable. The hybrid hydrogel was developed using the dynamic equilibrium of Schiff base linkage between the aldehyde groups on carboxymethyl cellulose dialdehyde (CMC-D) and amino groups on carboxymethyl chitosan (CMCh). The hydrogel stiffness and kinetics of gelation were observed to be modulated with different molecular weights of chitosan. In vitro studies demonstrated the cytocompatibility, hemocompatibility, and biodegradability of the hydrogel. The chemotactic, proliferative, and wound-healing response of cells to the paracrine factors secreted from the mesenchymal stem cell (MSC)-hydrogel composite confirmed the ability of the hydrogel to support the paracrine response of stem cells. Our results suggest that the synthesized hydrogel-MSC composite could serve as a potential scaffold for studying the in vitro response of cells to the paracrine factors released by the encapsulated cells as well as a cell delivery vehicle for in vivo applications.

Chitosan Cross-Linked Bio-based Antimicrobial Polypropylene Meshes for Hernia Repair Loaded with Levofloxacin HCl via Cold Oxygen Plasma

Polypropylene (PP) large pore size nets have been most widely used implants for hernia repair. Nevertheless, the growth of bacteria within PP mesh pores after operation is a major reason of hernia recurrence. Secondly, pre-operative prophylaxis during mesh implantation has failed due to the hydrophobic nature of PP meshes. Herein, chitosan cross-linked and levofloxacin HCl incorporated, antimicrobial PP mesh devices were prepared using citric acid as a bio-based and green cross-linking agent. The inert PP mesh fibers were surface activated using O2 plasma treatment at low pressure. Then, chitosan of different molecular weights (low and medium weight) were cross-linked with O2 plasma activated surfaces using citric acid. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy confirmed that chitosan was cross-linked with O2 plasma-treated PP mesh surfaces and formed a thin layer of chitosan and levofloxacin HCl on the PP mesh surfaces. Moreover, antimicrobial properties of chitosan and levofloxacin HCl-coated PP meshes were investigated using an agar plate release method. The coated PP meshes demonstrated excellent antimicrobial inhibition zone up to 10 mm. Thus, modified PP meshes demonstrated sustained antimicrobial properties for six continuous days against Staphylococcus aureus (SA) and Escherichia coli (EC) bacteria.

Stability improvement and characterization of bioprinted pectin-based scaffold.

Bioprinting is an alternative method for constructing tissues/organs for transplantation. This study investigated the cross-linker influence and post-printing modification using oligochitosan and chitosan for stability improvement. Oligochitosan was tested as a novel cross-linker to replace Ca2+ for pectin-based bio-ink. Oligochitosan (2 kD) and different molecular weight of chitosan were used to modify the bioprinted scaffold. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to characterize the scaffolds. Oligochitosan failed to serve as a viable cross-linker. Successful post-printing modification was confirmed by FTIR and SEM analyses. Regarding post-modification, chitosan-treated scaffolds showed enhanced stability compared to untreated scaffolds. In particular, scaffolds modified with 150 kD chitosan exhibited the highest stability.

Influence of Molecular Weight of Chitosan on Interaction with Casein

The process of complex formation of casein from skimmed milk and purified casein with chitosan of different molecular weights was studied. It was shown that at pH 6.3 casein micelles and parts of whey proteins coagulated with positively charged chitosan molecules with molecular weights of 45.3, 25.4, 7.7 and 1.5 kDa. As a result of ionic interaction of chitosan with skimmed milk proteins the yield of target product reached 90–92%. It consisted of all forms of casein: α-casein, β-casein, κ-casein and small amount of whey proteins.

Effects of Molecular Weight of Chitosan on the Biodegradability and Thermal Properties of Polybutylene Succinate/Chitosan Composites

In this study, the biodegradability and thermal properties the composites of polybutylene succinate (PBS) and chitosan of different molecular weights (Mn = 104,105, and 106 Da) were prepared at chitosan contents of 0-10 wt%. After 10 days of microbial degradation, the results show that the amount of holes from degradation was increased with either decreasing Mn or increasing chitosan contents. However, the size of holes was increased with increasing Mn and chitosan contents. The results from Differential Scanning Calorimeter (DSC) present that the melting temperature (Tm) of PBS was decreased with increasing chitosan contents. Moreover, there was no significant difference between Tm of the composites with different Mn of chitosan. From the TGA thermograms, the decomposition temperature at 10% weight loss (Td10) was decreased with increasing chitosan contents. Moreover, the water absorption of PBS/chitosan composites was increased with increasing Mn and content of chitosan.

Electrochemical Characterization of Chitosan Films As Proton-Conducting Layers for Bioprotonic Devices

We describe the lithographic fabrication, electrochemical characterization, and modeling of bioprotonic conduction channels, using a proof-of-concept material, chitosan, as a proton-conducting film deposited onto palladium electrodes. Linear sweep voltammetry (LSV) has been used to probe both the electrochemical generation of protons from H2 feed gas and the conduction of those protons through channels fabricated with different molecular weights of chitosan. Higher MW chitosan produces channels with significantly higher proton conductivity. Additionally, rigorous evaluation of the LSV data by both standard electroanalytical expressions and by digital simulation reveal that proton generation at the PdHx electrodes varies substantially between devices of different geometries. Multiple hydrogen oxidation reaction (HOR) pathways are operational at some devices, while at others a single pathway dominates. The analyses reveal the sensitivity of proton-generation kinetics on the chitosan/PdHxinterface, and furthermore, to the geometry of the device itself. Simulations of the proton conductivity in the chitosan membrane, however, yields excellent agreement between devices. Direct measurement of proton conductivity using electrochemical impedance spectroscopy further corroborates this agreement, yielding proton conductivity values nearly identical to those determined by analysis of the LSV results. This work is supported by the Office of Naval Research.

Influence of molecular weight of chitosan on the microstructures and photocatalytic property of ZrO2 prepared by chitosan templates method

ZrO2 particles with different microstructure have been fabricated through an easy method with chitosan of different molecular weights as template. The chitosan of different molecular weights was obtained through synergistic degradation of raw chitosan by α-amylase and H2O2 using microwave hydrothermal method in low concentration acetic acid (1% V/V). The as-synthesized ZrO2 particles were characterized by wide-angle powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and N2 adsorption⿿desorption. The possible formation mechanism of ZrO2 particles with different microstructure has been proposed, and the photocatalytic activity of the as-synthesized products was assessed by monitoring the photodegradation of Rhodamine B (Rh B) under UV irradiation. Morphologies of as-synthesized ZrO2 particles changed significantly with the different molecular weight of chitosan. As the molecular weight of chitosan decreased, the morphologies of as-synthesized ZrO2 particles showed aggregate, nano-cubes, and nano-sheets, respectively. The ZrO2 particles prepared with lower molecular weight chitosan as the template showed higher photocatalytic activity. The degradation efficiency of ZrO2 with 3.1ÿ107 and 2.4ÿ104Da chitosan as template was 64.4% and 86.2%, respectively.

Production and Properties of Different Molecular Weights of Chitosan from Marine Shrimp Shells

Production and Properties of Different Molecular Weights of Chitosan from Marine Shrimp Shells

Production of the low-molecular-weight chitin and chitosan forms in electron-beam plasma

The degradation of chitin and chitosans of different molecular weights stimulated by electronbeam plasmas of different gases has been experimentally studied. Biologically active water-soluble lowmolecular-weight chitooligosaccharides are formed as a result of plasma-beam treatment. It has been found that the degradation is a controlled process and products with a necessary molecular weight can be obtained by appropriately choosing plasma-beam treatment parameters (chemical composition of the plasma gas and treatment time and temperature).

Effect of chitosan molecular weight on the formation of chitosan–pullulanase soluble complexes and their application in the immobilization of pullulanase onto Fe3O4–κ-carrageenan nanoparticles

The interactions between pullulanase and chitosans of different molecular weights (Mw) were comprehensively studied, and their applications in pullulanase immobilization onto Fe3O4–κ-carrageenan nanoparticles upon chitosan–pullulanase complexation were also evaluated. Chitosan (CS) complexation with pullulanase was found to be dependent on pH and chitosan Mw. The critical pH of structure-forming events during complexation shifted significantly (p<0.05) to a lower pH with a low Mw chitosan (50kDa) compared to other chitosan types. Binding constants for the chitosan–pullulanase interaction increased in the following order: CS-500<CS-400<CS-50<CS-200. The binding induced alterations in the protein secondary structure, which may affect the enzymatic properties of immobilized pullulanase. Pullulanase immobilized upon CS-50 complexation exhibited the most desirable enzymatic properties. These results indicated that the complexation behavior was mainly dependent on chitosan Mw. This study presents a technique for the production of immobilized pullulanase upon complexation that exhibits potential for applications in continuous syrup production.

Eco-friendly innovation for nejayote coagulation–flocculation process using chitosan: Evaluation through zeta potential measurements

The main objective of the present paper is to discuss the convenience of using chitosan as a non-hazardous substance to improve the coagulation–flocculation (CF) efficiencies in nejayote (wastewater treatment containing high levels of total organic carbon, TOC=9836mg/L). For first time, two different molecular weight of chitosan in the wastewater treatment of the tortilla industry, were used as study models. The conditions here reported showed that both chitosans can be effectively used as adsorbent at pH 5.5 (mixing at 800rpm for 1min followed by a slow mixing at 200rpm for 5min) and at dosage of chitosan less than 3g/L for colloidal nejayote (without settleable solids). Both chitosan showed the highest performance under these conditions with more than 80% efficiency in turbidity removal, thus accomplishing the Mexican environmental regulation for free urban sewage discharge (NOM-002-SEMARNAT-1996). The zeta potential (ζ) of the nejayote supernatant before and after the CF treatment was used as a guiding parameter to evaluate each procedure. In addition, author suggest that the width of the flocculation window, for both chitosans in nejayote treatment, is attributed to their physical properties as molecular weight, deacetylation degree, dynamic viscosity and chemical properties as hydrogen bond, hydrophobicity and van der Waals interactions, as well as electrostatic forces that traditionally explain CF of colloids.

Synthesis, characterization, and controlled release of selenium nanoparticles stabilized by chitosan of different molecular weights

Chitosan-stabilized selenium nanoparticles (SeNPs) have been reported, but there is no information on the effect of the chitosan molecular weight on the structure, stability, and selenium release properties of the SeNPs. Herein, we compared the uniform Se0 spherical nanoparticles prepared through the reduction of seleninic acid with ascorbic acid in the presence of chitosan with different molecular weights (Mws). We found that both low and high molecular weight chitosan-stabilized selenium nanoparticles exhibited core–shell microstructures with a size of about 103nm after 30 days growing through the “bottom–up approach” and “top–down approach,” respectively. Moreover, both chitosan SeNPs processed excellent stability towards pH and enzyme treatment. In contrast, selenium was easily released to different extents from these two chitosan SeNPs upon treatment with different free radicals. This makes these materials potentially useful as oral antioxidant supplements.