Effect of Chitosan Deacetylation on Its Affinity to Type III Collagen: A Molecular Dynamics Study

The ability to form strong intermolecular interactions by linear glucosamine polysaccharides with collagen is strictly related to their nonlinear dynamic behavior and hence bio-lubricating features. Type III collagen plays a crucial role in tissue regeneration, and its presence in the articular cartilage affects its bio-technical features. In this study, the molecular dynamics methodology was applied to evaluate the effect of deacetylation degree on the chitosan affinity to type III collagen. The computational procedure employed docking and geometry optimizations of different chitosan structures characterized by randomly distributed deacetylated groups. The eight different degrees of deacetylation from 12.5% to 100% were taken into account. We found an increasing linear trend (R2 = 0.97) between deacetylation degree and the collagen–chitosan interaction energy. This can be explained by replacing weak hydrophobic contacts with more stable hydrogen bonds involving amino groups in N-deacetylated chitosan moieties. In this study, the properties of chitosan were compared with hyaluronic acid, which is a natural component of synovial fluid and cartilage. As we found, when the degree of deacetylation of chitosan was greater than 0.4, it exhibited a higher affinity for collagen than in the case of hyaluronic acid.

Impact of Chitosan on Water Stability and Wettability of Soils

Chitosan has become increasingly applied in agriculture worldwide, thus entering the soil environment. We hypothesized that chitosan should affect the water stability of soil. Since this problem has not been studied to date, we examined, for the first time, the influence of chitosan on the water stability and wettability of soil aggregates. The aggregates were prepared from four soils with various properties amended with different amounts of two kinds of powdered chitosan, and subjected to 1 and/or 10 wetting–drying cycles. The water stability was measured by monitoring air bubbling after aggregate immersion in water, and the wettability was measured by a water drop penetration test. The biopolymer with a lower molecular mass, lower viscosity, and higher degree of deacetylation was more effective in increasing the water stability of the soil than the biopolymer with a higher molecular mass, higher viscosity, and lower deacetylation degree. After a single wetting-drying cycle, the water stability of the soil aggregates containing chitosan with a higher molecular mass was generally lower than that of the soil; after ten wetting–drying cycles, the water stability increased 1.5 to 20 times depending on the soil. The addition of low-molecular-mass chitosan after a single wetting-drying cycle caused the water stability to become one to two hundred times higher than that of the soil. A trial to find out which soil properties (pH, C and N content, bulk density, porosity, and particle size distribution) are responsible for the effectiveness of chitosan action was not successful, and this will be the objective of further studies.

Iron Encapsulation by Deacetylated Glucomannan as an Excipient Using the Gelation Method: Characteristics and Controlled Release

Research background. Deacetylation and the use of CaCl2 as a gelation agent improve the performance of glucomannan as iron encapsulant using the gelation method. This study was conducted to investigate the effects of deacetylation using NaOH and pH gelation on the characteristics of encapsulated iron using the CaCl2 gelation method. Experimental approach. Glucomannan was deacetylated at various NaOH concentrations and was subsequently utilized as an iron excipient using the pipette-dropped gelation method in CaCl2 solution to directly investigate the gelation process of encapsulation. The pH of the gelation solution was also changed. The beads were subsequently vacuum-dried. Results and conclusions. Deacetylation led to lower endothermic peak temperature of the glucomannan than that of the native one. The deacetylation degree (DD) and gelation pH did not significantly affect the diameter of the beads but influenced their appearance and physical characteristics. The backbone of glucomannan was not changed by either the deacetylation degree or the pH of the gelation treatment. The highest encapsulation efficiency (73.27 %) was observed in the encapsulated iron using the glucomannan matrix of the highest deacetylation degree (82.56 %) and gelated in pH=10 solution. The highest deacetylation degree of glucomannan caused the beads to have the highest swelling, which led to the release of a higher amount of iron. Glucomannan deacetylation improved the pH sensitivity of iron encapsulation, in which more iron was released at a pH=6.8 than of pH=1.2. The Weibull model was the best-fitted model to represent the profile of iron release from the deacetylated glucomannan matrix using the gelation method (R2 > 0.93) at pH=6.8 and pH=1.2 solutions. Novelty and scientific contribution. This result supports the application of deacetylated glucomannan using NaOH as a pH-sensitive matrix on iron encapsulation using CaCl2 solution as gelation agent. A higher deacetylation degree leads to the release of a higher amount of iron from the matrix. The encapsulation is not only protecting the iron but also delivering it to the absorption site and controlling the iron release which are useful in supplement formulation. or food fortifications. The results show that the deacetylated glucomannan as the matrix holds more iron in encapsulation process.

Synthesis and antibacterial activity of chitosan membrane from shrimp shell waste

Synthesis and antibacterial activity of chitosan membrane was investigated. Chitosan membrane have been successfully by simple method from chitosan extracted from shrimp shell waste. Extraction of chitosan was carried out in four steps: demineralization, deproteinization, decolorization and deacetylation of chitin. The effect of deacetylation temperature on deacetylation process was studied. The results shown that the increase of deacetylation temperature from 30°C to 90°C causes the increase of chitosan deacetylation degree (DD). The increase of deacetylation temperature cause the increment of OH- attack to the amino group thus realizing the effective deacetylation of chitin. The highest chitosan DD was up to 77.99% is achieved under the deacetylation temperature from 90°C and the occurrence of deacetylation structurally demonstrated by the Fourier transform infrared (FTIR) and the XRD characterization. The antimicrobial test results used S. epidermidis and P. acne of chitosan membrane at various deacetylation temperature conditions indicated that no bacterial activity for all variants.

THE EFFECT OF CHITOSAN HYDROLYSATE ON THE FUNGI ALTERNARIA SOLANI, FUSARIUM SOLANI AND RHIZOCTONIA SOLANI IN VITRO

Chitosan hydrolysate was obtained using nitric acid; the prevailing fraction had a molecular weight of 30 kDa and a deacetylation degree of 95%. The effect of chitosan hydrolysate when added to potato dextrose agar (PDA) in different concentrations (0.5, 1, 1.5, 2, 4, 6 and 8 mg/mL) was studied on the growth of the fungi Alternaria solani Sorauer, Fusarium solani (Mart.) Sacc. and Rhizoctonia solani J.G. Kühn. A. solani was the most sensitive to the addition of chitosan hydrolysate to PDA in radial growth experiments. On days 3 and 7 of incubation, the antifungal activity of the phytopathogen growth was 69%-92% and 69%-88%, respectively, in the concentration range of 0.5-2 mg/ml.

LONG-TERM RADIATION-INDUCED EFFECTS ON SOLID STATE CHITOSAN

Treatment of chitosan with ionising radiation is one of the methods by which it is modified for various applications. However, in the case of chitosan irradiated in the solid state, the radicals formed during irradiation can be stabilised in its crystalline phase and subsequently cause post-irradiation changes. It has been observed that further degradation of the polymer occurs during storage of the irradiated polymer, resulting in an increase in oxidation products and a decrease in deacetylation degree. This effect results from the transformation of radicals leading to the formation of stable nitroxyl radicals, a process observed years after irradiation.

Effect of Ultrasonic Assisted on The Degree of Deacetylation of Chitosan Extracted from Portunus Pelagicus

The technology for extracting chitin from shell and other materials needs to be continuously improved, including its conversion to chitosan. Chitosan is a biocompatible polymer, biodegradable, non-toxic, water-soluble at pH below 6.5, and it has protonated amino groups. The benefits of chitosan in industry, food and medicine make it necessary to fully study an efficient chitosan synthesis method and the results can be applied on an industrial scale. This study examined the effect of ultrasonic-assisted in increasing the degree of deacetylation of chitosan produced from Portunus pelagicus shell waste. The production process of chitosan goes through the stages of deproteination, demineralization and deacetylation. All these steps are ultrasound assisted processes with a frequency of 40 kHz through a digital ultrasonic cleaner. Ultrasonic-assisted chitin and chitosan were examined using FTIR spectrometry. The results showed that the ultrasonic method was able to increase the deacetylation degree of chitin with a value of 68.45±0.11% compared to 62.52±0.08% without ultrasonic. Application of ultrasonic assisted deacetylation gave a deacetylation degree of 85.35 ± 0.20%, higher than without ultrasonic 80.24 ± 0.19%. Physically, ultrasonic-assisted chitosan is smoother and brighter in color. The ultrasonic-assisted chitosan manufacturing method could increase the deacetylation degree and produce high grade chitosan.