Deacetylation Degree Of Chitosan Research Articles

Abstract 3188: Chitosan-glycerol injectable gel for intratumoral retention of immunotherapeutics

Abstract A novel, injectable chitosan-glycerol hydrogel was developed and characterized. Upon injection with co-formulated therapeutics, the gel vastly improved molecule retention at the injection site, as compared to molecule delivery in less viscous media. Methods. The hydrogel was formed through a centrifugation process. 70% deacetylated, medium viscosity chitosan was dissolved in 0.1M HCl. Glycerol was then added, followed by vortexing. Next, 1x PBS and 1M NaOH were added to neutralize the mixture, which induced gelation. After hydrogel centrifugation at 10,000 rpm for 5 minutes, a hydrogel was separated from precipitate. Several formulation parameters were tested, including chitosan:glycerol volume ratio, chitosan concentration, chitosan degree of deacetylation, and chitosan molecular weight. The retention of model therapeutics, formulated in hydrogel or saline vehicles, following injection in agar-based tumor phantoms was quantified via absorbance and fluorescence readings. To assess biocompatibility, a non-contact cell viability assay was performed utilizing 3T3 fibroblasts seeded in the bottom of transmembrane wells with hydrogels added to the upper chamber. After 48 hours, cells were collected and counted utilizing trypan blue. New Data. A hydrogel for intratumoral therapeutic delivery was constructed with several desirable qualities, including biocompatibility and injectability through a 25-gauge needle. Different relative glycerol to chitosan volumes, from 5 to 95 w/v % glycerol, were tested to determine a range of gelation conditions. Glycerol volume most significantly impacted gelation conditions independent of chitosan concentration, with gelation occurring between 70-85% relative volume glycerol. Increasing chitosan solution concentration and chitosan molecular weight increased the range of chitosan:glycerol ratios resulting in gelation. The hydrogel improved load retention at the agar tumor phantom injection site for various sizes of model therapeutics compared to less viscous solutions. Cytotoxicity testing of the hydrogel showed a statistically insignificant difference between the live:dead cell ratios of the experimental and negative control groups. Conclusion. An injectable, biocompatible hydrogel was created through the neutralization and centrifugation of a chitosan-glycerol solution. The hydrogel displays physiological pH, injectability through a 25-gauge needle, biocompatibility, and vastly improved therapeutic load retention at the injection site compared to less-viscous delivery media. Chitosan-glycerol hydrogels may be useful for intratumoral delivery and retention of immunomodulators within the tumor microenvironment. Citation Format: Robert L. Kobrin, Siena M. Mantooth, David A. Zaharoff. Chitosan-glycerol injectable gel for intratumoral retention of immunotherapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3188.

Soy conglycinin amyloid fibril and chitosan complex scaffold for cultivated meat application

This study addresses the critical need in cultivated meat production for suitable scaffolds that support the growth and differentiation of muscle cells. We explore the synergy of soy conglycinin (7S) amyloid protein fibrils and chitosan to create three-dimensional (3D) porous scaffolds, specifically designed for this application. By varying the molecular weight and deacetylation degrees of chitosan, we employed a controlled temperature water annealing method to produce these complex scaffolds. The formation mechanism of the 7S-chitosan scaffolds was elucidated through molecular simulation and Fourier-transform infrared (FTIR) analysis. Characterization of the scaffolds revealed pore sizes within the 50–250 μm range, porosities from 71% to 78%, and compressive moduli varying between 4.8 and 15.3 kPa, dependent on the chitosan's deacetylation degree and molecular weight. Notably, these scaffolds maintained structural integrity in refrigerated Phosphate Buffered Saline (PBS) for up to three months and effectively supported the growth and differentiation of C2C12 mouse skeletal muscle cells without necessitating additional cell adhesion enhancements. Their mechanical properties, comparable to natural muscle tissue, and compatibility with high-temperature sterilization processes, underscore their potential as innovative solutions in the field of cultivated meat production.

Synthesis and comprehensive characterization with anticancer activity assessment of salicylaldehyde and 2-acetylphenol based chitosan thiosemicarbazones and their copper(II) complexes

Functionalization of chitosan as salicylaldehyde and 2-acetylphenol-based chitosan thiosemicarbazone involving amino group at C2 position of pyranose ring was confirmed by comprehensive characterization by spectroscopic and analytical ways. Both the low molecular weight (Mw) chitosan oligosaccharide (CS) (Mw < 3000 Da, degree of deacetylation (DDA) = 87 %) and the crab shell chitosan (CCS) (Mw = 350 kDa, DDA = 67 %) functionalized thiosemicarbazones behaved as ONS tridentate ligand to form the square planar copper(II) complexes with a chloride ion as an additional ligand to satisfy the co-ordination sphere. All the derivatives were found thermally stable till the commencement of chitosan backbone disruption at 200 °C. The MTT assay profiles showed a conspicuous enhancement in the in vitro antitumorigenic and anticancer activity of native chitosan upon its functionalization as phenolic carbaldehyde chitosan thiosemicarbazones. Further, the assays more often revealed a further lowering of cell viability with chitosan oligosaccharide derivatives in comparison to high molecular weight chitosan derivatives, and a lower viability of the MCF-7 cancer cells than the tumorigenic MDCK cells. Both the low Mw chitosan with high DDA and high Mw chitosan with low DDA, the chitosan-functionalized salicylaldehyde based thiosemicarbazones, and their copper(II) chitosan thiosemicarbazone complexes were found to have minimal toxicity with IC50 >600 μgmL−1 against the mouse embryonic normal fibroblast NIH3T3 cells. These results were indicatives of more protonation and enhanced anticancer activity of chitosan oligosaccharide derivatives, and preferential cytotoxicity of chitosan biomaterials against the tumorigenic and cancer cells with more negatively charged cell surfaces.

Synthesis and characterization of chitosan-copper nanocomposites and their catalytic properties for 4-nitrophenol reduction

Biopolymer-based copper nanoparticles (CuNPs) have become an area of significant interest due to their wide-ranging applications in a variety of fields. However, there remains a challenge in tailoring their morphologies and improving their properties. In this study, CuNPs were synthesized via wet chemical reduction using sodium hypophosphite monohydrate (NaH2PO2·H2O), l-ascorbic acid and chitosan. The effect of different synthesis conditions, including reaction pH, temperature, time, concentration of NaH2PO2·H2O, l-ascorbic acid and chitosan, as well as the deacetylation degree (DD) of chitosan, on the synthesis of CuNPs was investigated. The synthesized CuNPs were characterized by various analytical techniques. The catalytic properties of synthesized CuNPs were investigated for the reduction of 4-nitrophenol (4-NP) in the presence of sodium borohydride. The synthesis-morphology-catalytic activity relationship of CuNPs was discussed. The results suggested that the morphology of CuNPs could be adjusted by controlling the synthesis conditions. Chitosan DD significantly impacts the morphology of the synthesized CuNPs. As the chitosan DD decreased from 91.8 % to 52.3 %, the average particle size of synthesized CuNPs decreased from 43.9 ± 10.6 to 17.7 ± 5.9 nm and the shape changed from anisotropy to near-sphere. CuNPs synthesized using low DD (53.2 %) chitosan (CuNPs-N3) demonstrated the highest 4-NP conversion rate of 99.1 % and reaction rate constant of 0.3540 min−1. CuNPs-N3 was thermodynamically and kinetically more feasible than CuNPs synthesized with high DD chitosan. These findings provide important insights for further designing and developing hierarchical nanostructured CuNPs catalysts for broader applications.

Insect residues as an alternative and promising source for the extraction of chitin and chitosan

This work aimed to obtain and characterize chitin and chitosan extracted from the rearing residues of Tenebrio molitor, Zophobas morio, and Blaptica dubia insects in different growth stages in the same rearing cycles chitin and chitosan yielded 11.21 %–20.89 % and 6.26 %–7.07 %, respectively. The deacetylation degrees of chitosan ranged from 75.75 %–89.21 %, and the solubilities from 69.88 %–94.39 %. Infrared spectroscopy corroborated the acquisition of chitin and chitosan and can be used as a semi-quantitative technique for determining the degree of chitosan deacetylation. The X-ray diffraction profiles revealed the presence of α-chitin, and the relative crystalline indices ranged from 65.9 %–89.2 %. Typical TG profiles with two thermal events are observed for chitin and chitosan samples with different residue contents from the extraction procedure. The chitosan solutions exhibited pseudoplastic behavior, with apparent viscosities ranging from 195.96 to 249.86 mPa.s. The characterization results of the biopolymers extracted from insect residues were similar to those obtained from conventional sources. The growth stage influenced the chitin yield and crystallinity index. The results of this study reinforce the feasibility of using alternative sources of chitin and chitosan, providing the use of waste from insect farms and contributing to sustainability and a circular economy.

Creation of Chemically Tri-Layered Collagen Crosslinked Membranes and Their Comparison with Ionically Tri-Layered Chitosan Crosslinked Membranes to Study Human Skin Properties.

In 2009, a new European regulation came into force that forbade the use of animals in the cosmetics industry. As a result, new alternatives were sought, taking into account the new ethical considerations. The main objective of this article is to continue a line of research that aims to build a physical model of skin from a biomaterial scaffold composed of collagen, chitosan or a combination to investigate whether they offer similar behavior to human skin. Collagen, the major component in the dermis, was crosslinked with glutaraldehyde (GTA) to develop three formulations for studying some properties of the skin through rheological tests like swelling index, elasticity or water loss. In addition, this article makes a comparison with the results obtained in the previous article where the membranes were made of chitosan and tripolyphosphate (TPP). The results obtained highlight that the tri-layered membranes scaffold better than the mono-layered ones to increase the elastic modulus (G') and the permeability. Furthermore, they offer a protective effect against water loss compared to mono-layered membranes. As regards chitosan membranes, these have a higher G' modulus than collagen membranes when the degree of deacetylation (DDA) is 85%. However, collagen membranes are more elastic when the DDA of chitosan is 76%, and their linear viscoelastic limit (LVL) doubles that of chitosan membranes, both for the degree of acetylation of 76 and 85%.

Effects of deacetylation degree of chitosan on the structure of aerogels

Chitosan aerogels, obtained by (supercritical) CO2 drying of hydrogels, are novel adsorbents because of their large surface area and high porosity. Intrinsic properties of chitosan such as molecular weight (MW) and degree of deacetylation (DDA) had large impacts on the characteristics of chitosan aerogels. Although there are a few studies about the effects of solely DDA or MW on aerogel structure, none of them has focused on the mutual effects. The study aims to investigate the combined effects of MW and DDA of chitosan on aerogel properties. Hydrogels were produced in beads form by physical gelation of the chitosan solutions (2 % w/v in acetic acid of 1 %, v/v) in an alkaline environment (NaOH, 4 N). Supercritical CO2 dried aerogels were examined with respect to the bulk density, diameter as well as pore characteristics, and surface area by Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) methods, respectively. Morphologies of aerogels were also examined by Scanning Electron Microscopy (SEM) images and structural changes of aerogels were observed by Fourier Transform Infrared (FTIR) Spectroscopy. Additional to BET-BJH analysis, proton relaxation dispersion was measured by Fast Field Cycling NMR (FFC-NMR) to determine the pore volume of the aerogels. Compact structures were obtained for higher MW chitosan and lower MW chitosans with higher DDA increasing the aerogel diameters. All types of aerogels obtained by different chitosan characteristics (MW and DDA) showed a porous structure and the highest DDA with the lowest MW caused the minimum bulk density with the highest water absorption rate. Although different N2 adsorption-desorption profiles were obtained in terms of pore volumes; all aerogels had Type IV isotherms with Type H1 hysteresis curve. FFC-NMR experiments showed that the coherence length values were associated with the pore volumes and FFC-NMR experiments were found to be meaningful as supportive experiments for the characterization of aerogels.

Effect of deacetylation of chitosan on physicochemical properties, antioxidant and antibacterial activities of chitosan-mannose derivatives.

This paper investigates the physical, chemical, and antibacterial properties of water-soluble chitosan derivatives. Preparation of the water-soluble chitosan derivatives was done by the Maillard reaction (MR) between chitosan (the degree of deacetylation (DD) being 50%, 70%, and 90%) and mannose. No organic reagent was used in the process. Systematic evaluations of the effects of chitosan DD on the reaction extent, the structure, the composition, as well as the physicochemical properties, antioxidant properties, and bacterial inhibitory properties of the finished chitosan-mannose Maillard reaction products (Mc-mrps) were carried out. Based on the experimental data obtained from the Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Pyrolysis-gas chromatography-mass analysis (PY-GC-MS), and 1H-NMR, the Mc-mrps formed from chitosan with different DDs had different structures and components. An increase in the DD of chitosan led to a significant increase in the degree of reaction, color difference (△E), and solubility (p<0.05). The zeta potential and particle size of the Mc-mrps were also influenced by the DD of chitosan. Additionally, the antimicrobial action against Gram-positive (S.aureus and Bacillus subtilis) and Gram-negative bacteria (E.coli and Salmonella typhimurium) as well as antioxidant activity were enhanced by the incorporation of mannose. This was also achieved by the increase of the DD of chitosan. The results of the study suggest that chitosan was derived with mannose to yield a novel, water-soluble polysaccharide with better antioxidant and antimicrobial activities. The DD of chitosan had a significant effect on the properties of the Mc-mrp, which can serve as a reference point for the subsequent preparation and application of such derivatives. This article is protected by copyright. All rights reserved.

Impact of molecular weight and deacetylation degree of chitosan on the bioaccessibility of quercetin encapsulated in alginate/chitosan-coated zein nanoparticles

This work aimed at studying the effect of molecular weight (MW) and deacetylation degree (DD) of chitosan on the quercetin bioaccessibility encapsulated in alginate/chitosan-coated zein nanoparticles (alg/chiZN). The chitosan coating layer produced nanoparticulate systems with good stability parameters, high encapsulation efficiency (EE) and a higher bioaccessibilty of quercetin after in-vitro digestion. By increasing the DD of chitosan, the ζ-potential of the colloidal system significantly increased (≥27.1 mV), while low and very low MW chitosans generated systems with smaller particle sizes (≤ 277.8 nm) and polydispersity index [PDI (0.189)]. The best results, in terms of EE (≥84.44) and bioaccessibility (≥76.70), were obtained when the systems were prepared with low MW chitosan and high DD. Thus, the alg/chiZN nanocapsules may be a promising delivery system for improving the quercetin bioaccessibility or other compounds with a similar chemical nature, especially when higher DD and lower MWs are used.

Synergistic depolymerisation of alginate and chitosan by high hydrostatic pressure (HHP) and pulsed electric fields (PEF) treatment in the presence of H2O2

Physically-induced depolymerisation procedures are often preferred for obtaining alginate and chitosan oligosaccharides as they either do not use or make minimal use of additional chemicals; therefore, separation of the final products is facile. In this work, solutions of three types of alginate with different mannuronic and guluronic acid residues ratio (M/G ratio) and molecular weights (Mw) and one type of chitosan were non-thermally processed by applying high hydrostatic pressures (HHP) up to 500 MPa (20 min) or pulsed electric fields (PEF) up to 25 kV cm−1 (4000 μm) in the absence or presence of 3 % hydrogen peroxide (H2O2). The impact on the physicochemical properties of alginate and chitosan was investigated by rheology, GPC, XRD, FTIR, and 1H NMR. In the rheological investigations, the apparent viscosities of all samples decreased with increasing shear rate, indicating a non-Newtonian shear-thinning behaviour. GPC results reported Mw reductions that ranged between 8 and 96 % for all treatments. NMR results revealed that HHP and PEF treatment predominantly reduced the M/G ratio of alginate and the degree of deacetylation (DDA) of chitosan, whilst H2O2 promoted an increase in the M/G ratio in alginate and DDA of chitosan. Overall, the present investigation has demonstrated the feasibility of HHP and PEF for rapidly producing alginate and chitosan oligosaccharides.

Hydrogel Preparation from Shrimp Shell-Based Chitosan: The Degree of Crosslinking and Swelling Study

Chitosan is a natural polymer derived from different starting materials such as fish scales, crab and shrimp shells. Due to the advantages like biocompatibility and biodegradability, chitosan has been widely used in hydrogel development. This current study aims to make chitosan from shrimp shells, synthesize hydrogel from chitosan, and observe the effect of various chitosan preparation treatments on the properties of the hydrogel. The preparation of chitosan was carried out through demineralization, deproteinization, and deacetylation process. HCl concentration during demineralization and NaOH concentration during deproteinization were varied (1; 1,5; 2) M and (1; 1,5; 2) M, respectively. Chitin deacetylation was conducted using 60% (w/v) of NaOH at the temperature of 90oC for 120 min, and chitosan was resulted. Chitosan based hydrogel was then synthesized with the addition of alginate and glutaraldehyde. The effect of HCl and NaOH concentrations during demineralization and deproteinization on the deacetylation degree of chitosan was observed. The effect of deacetylation degree of chitosan on the degree of crosslinking and swelling property of the hydrogel were also evaluated. Chitosan resulted from this study has the optimum degree of deacetylation at 57.28 %, resulting from demineralization by using HCl 2M and deproteinization with NaOH2 M. Higher deacetilation degree of chitosan causing the increase of the degree of cross-linking and decrease of the swelling capacity of the hydrogel. The highest degree of cross-linking is 78.85 %, and the swelling capacity is 47 %.

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.

Influence of chitosan source and degree of deacetylation on antibacterial activity and adsorption of AZO dye from water

AbstractChitosan is one of the most abundant biopolymers in nature with high economic value due to its biocompatibility, biodegradability, lack of toxicity, and antifungal activity. In this study, chitosan was extracted from three different sources: Blaps lethifera (CSB), Pimelia fernandezlopezi (CSP), and Musca domestica (CSM). The ash content (AC), moisture content (MC), fat binding capacity (FBC), water binding capacity (WBC), and deacetylation degree (DD) were determined for the prepared chitosans. The effect of the DD of chitosan on the antibacterial activity of gram (positive/negative) bacteria and the azo dyes (methylene blue, MB) removal from wastewater was also investigated. Chitosan extracts showed good antibacterial activity against Listeria innocua, Bacillus subtiliis, Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa. The MB dye removal of CSB-chitosan, CSP-chitosan, and CSM-chitosan reached 37%, 87%, and 26%, respectively, at a contact time of 2 h, a low initial dye concentration MB of 13 ppm, a solution temperature of 25 °C, and a pH = 7. Graphical Abstract

Effect of Degree of Deacetylation of Chitosan/Chitin on Human Neural Stem Cell Culture.

Stem cell therapy and research for neural diseases depends on reliable reproduction of neural stem cells. Chitosan-based materials have been proposed as a substrate for culturing human neural stem cells (hNSCs) in the pursuit of clinically compatible culture conditions that are chemically defined and compliant with good manufacturing practices. The physical and biochemical properties of chitosan and chitin are strongly regulated by the degree of deacetylation (DD). However, the effect of DD on hNSC behavior has not been systematically investigated. In this study, films with DD ranging from 93% to 14% are fabricated with chitosan and chitin. Under xeno-free conditions, hNSCs proliferate preferentially on films with a higher DD, exhibiting adherent morphology and retaining multipotency. Lowering the DD leads to formation of neural stem cell spheroids due to unsteady adhesion. The neural spheroids present NSC multipotency protein expression reduction and cytoplasmic translocation. This study provides an insight into the influence of the DD on hNSCs behavior and may serve as a guideline for hNSC research using chitosan-based biomaterials. It demonstrates the capability of controlling hNSC fate by simply tailoring the DD of chitosan.

Chitosan as a Functional Carrier for the Local Delivery Anti-Inflammatory Systems Containing Scutellariae baicalensis radix Extract.

The aim of the study was to establish the influence of chitosan on the preparation of systems containing Scutellariae baicalensis radix extract and to demonstrate the potential of anti-inflammatory action for the treatment of periodontitis. In the first stage, the impact of the variables (extraction mixture composition, temperature, and the number of extraction cycles) on the extracted samples’ biological characteristics was analyzed using the Design of Experiments (DoE) approach. The best conditions for baicalin, baicalein, and wogonin extraction from Scutellariae baicalensis radix were 80% methanol in the extraction mixture, 70 °C, and 4 cycles per 60 min. The DoE approach can be used to choose the best chitosan system parameters with equal success. An increase in the deacetylation degree of chitosan used in the system improved the potential for reducing free radicals and inhibiting the hyaluronidase enzyme. Also, increasing the degree of chitosan deacetylation results in increased resistance of the carrier to biodegradation and an extended baicalin release profile, which is also associated with an increase in the viscosity of the chitosan-based system. In total, the system of a freeze-dried extract with chitosan 90/500 in the ratio of 2:1 (system S9) turns out to be the one with the best physicochemical (high percentage of baicalin release and the highest viscosity conditioning the prolonged stay at the site of administration) and biological properties (the highest antioxidant and anti-inflammatory activities), resulting in the highest potential for use in the treatment of oral inflammatory diseases.

Accurate Determination of the Degree of Deacetylation of Chitosan Using UPLC–MS/MS

The mole fraction of deacetylated monomeric units in chitosan (CS) molecules is referred to as CS’s degree of deacetylation (DD). In this study, 35 characteristic ions of CS were detected using liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI–MS/MS). The relative response intensity of 35 characteristic ion pairs using a single charge in nine CS samples with varying DDs was analyzed using 30 analytical methods. There was a good linear relationship between the relative response intensity of the characteristic ion pairs determined using ultrahigh performance (UP) LC–MS/MS and the DD of CS. The UPLC–MS/MS method for determining the DD of CS was unaffected by the sample concentration. The detection instrument has a wide range of application parameters with different voltages, high temperatures, and gas flow conditions. This study established a detection method for the DD of CS with high sensitivity, fast analysis, accuracy, stability, and durability.

Effects of chitosan molecular weight and deacetylation degree on the properties of collagen‐chitosan composite films for food packaging

AbstractComposite films based on collagen and chitosan with different molecular weights (MWs) and deacetylation degree (DD) are prepared for food packaging. Fourier‐transform infrared analysis indicates that more hydrogen bonds have formed between collagen molecules and chitosan with larger MW or higher DD due to their more reactive groups for interactions. The light barrier capacity, mechanical, and thermal properties of the composite films enhanced with increasing the MW or DD of chitosan. However, composite film with the lowest MW of 50 kDa possesses the best antioxidative and antibacterial activities. Among all the films, composite films containing chitosan with low MW of 50 kDa and high DD of 95% exhibit better preservation effect in pork. The shelf life of pork wrapped with film containing chitosan of 50 kDa has been extended to 3 days with the lowest total volatile basic nitrogen level (12.13 mg/100 g), thiobarbituric acid reactive substance value (0.541 mg malondialdehyde/kg) and total viable count (5.64 log colony forming unit/g). These results indicate that MW and DD of chitosan are two important factors that should be considered when designing collagen‐chitosan composite films for food packaging.

Characterization, antimicrobial and cytotoxic activity of polymer blends based on chitosan and fish collagen

This study aims to produce, characterize, and assess the antimicrobial activity and cytotoxicity of polymer blends based on chitosan (CT) and fish collagen (COL) produced by different precipitation methods. Polymer blends were obtained in alkaline (NaOH), saline (NaCl), and alkaline/saline (NaOH/NaCl) solutions with different CT:COL concentration ratios (20:80, 50:50, and 80:20). The polymer blends were characterized by various physicochemical methods and subsequently evaluated in terms of their in vitro antimicrobial and cytotoxicity activity. In this study, the degree of chitosan deacetylation was 82%. The total hydroxyproline and collagen content in the fish matrix was 47.56 mg. g−1 and 394.75 mg. g−1, respectively. The highest yield was 44% and was obtained for a CT:COL (80:20) blend prepared by precipitation in NaOH. High concentrations of hydroxyproline and collagen in the blends were observed when NaOH precipitation was used. Microbiological analysis revealed that the strains used in this work were sensitive to the biomaterial; this sensitivity was dose-dependent and increased with increasing chitosan concentration in the products. The biocompatibility test showed that the blends did not reduce the viability of fibroblast cells after 48 h of culture. An analysis of the microbiological activity of the all-polymer blends showed a decrease in the values of minimal inhibitory concentration (MIC) and minimal bactericidal concentrations (MBC) for S. aureus and P. aeruginosa. The blends showed biocompatibility with NIH-3T3 murine fibroblast cells and demonstrated their potential for use in biomedical applications such as wound healing, implants, and scaffolds.

Influence of Deacetylation Degree of Chitosan on the Anticorrosive Properties of Carbon Steel Coatings

AbstractThis study outlines the improvement on anticorrosion behavior of chitosan‐based sol‐gel coatings on carbon steel surface obtained for high deacetylation degree values of this natural biopolymer. Important economic losses in major industries represent a problem due to corrosion of metals in aggressive medium, such as carbon steel, which is widely used due to its hardness, durability, ductility, low cost, handiness. Therefore, non‐toxic, cost‐effective, and eco‐friendly strategies are needed to protect metallic surface of steel. Against this background, the anticorrosion coating performance of chitosan, from three different commercial sources, as a single component, on carbon steel in chloride solutions is investigated using electrochemical impedance spectroscopy technique. The present study is performed to evaluate the corrosion protective abilities of chitosan in order to determine the relationship with its deacetylation degree (DDA), evaluated by potentiometric titration, a simple and reliable method. Depending on the DDA, the experimental results indicate that there is a remarkable difference between different chitosan samples regarding the value of the charge transfer resistance of coating on steel.

Antibacterial Bio-Nanocomposite Textile Material Produced from Natural Resources.

Growing demand for sustainable and green technologies has turned industries and research toward the more efficient utilization of natural and renewable resources. In an effort to tackle this issue, we developed an antibacterial textile nanocomposite material based on cotton and peat fibers with immobilized Cu-based nanostructures. In order to overcome poor wettability and affinity for Cu2+-ions, the substrate was activated by corona discharge and coated with the biopolymer chitosan before the in situ synthesis of nanostructures. Field emission scanning electron microscopy (FESEM) images show that the application of gallic or ascorbic acid as green reducing agents resulted in the formation of Cu-based nanosheets and mostly spherical nanoparticles, respectively. X-ray photoelectron spectroscopy (XPS) analysis revealed that the formed nanostructures consisted of Cu2O and CuO. A higher-concentration precursor solution led to higher copper content in the nanocomposites, independent of the reducing agent and chitosan deacetylation degree. Most of the synthesized nanocomposites provided maximum reduction of the bacteria Escherichia coli and Staphylococcus aureus. A combined modification using chitosan with a higher deacetylation degree, a 1 mM solution of CuSO4 solution, and gallic acid resulted in an optimal textile nanocomposite with strong antibacterial activity and moderate Cu2+-ion release in physiological solutions. Finally, the Cu-based nanostructures partially suppressed the biodegradation of the textile nanocomposite in soil.