Effect Of Deacetylation Degree Research Articles

Chitosan-Based Hemostatic Hydrogels: The Concept, Mechanism, Application, and Prospects.

The design of new hemostatic materials to mitigate uncontrolled bleeding in emergencies is challenging. Chitosan-based hemostatic hydrogels have frequently been used for hemostasis due to their unique biocompatibility, tunable mechanical properties, injectability, and ease of handling. Moreover, chitosan (CS) absorbs red blood cells and activates platelets to promote hemostasis. Benefiting from these desired properties, the hemostatic application of CS hydrogels is attracting ever-increasing research attention. This paper reviews the recent research progress of CS-based hemostatic hydrogels and their advantageous characteristics compared to traditional hemostatic materials. The effects of the hemostatic mechanism, effects of deacetylation degree, relative molecular mass, and chemical modification on the hemostatic performance of CS hydrogels are summarized. Meanwhile, some typical applications of CS hydrogels are introduced to provide references for the preparation of efficient hemostatic hydrogels. Finally, the future perspectives of CS-based hemostatic hydrogels are presented.

Effect of deacetylation degree and molecular weight on surface properties of chitosan obtained from biowastes

A surface characterization of two types of unmodified chitosan properties with different molecular weight (MW) and deacetylation degree (DD) was carried out in terms of polymer concentration (a concentration lower than the saturation, the saturation concentration and a supersaturated concentration). The modification of the production conditions allowed to obtain chitosan samples with different properties (MW and DD), which eventually determined its surface activity. Thus, a kind of tailor-made chitosan may be designed to be adapted to different applications. Surface activity has been analysed by mean of measurements of surface tension, dilatational and shear rheology. The results have demonstrated that chitosan possessed a good surface activity at high ionic strength. Also, the increase in the concentration of chitosan in the solution, and the increase in molecular weight (and, therefore, a decrease in the degree of deacetylation) favoured the formation of aggregates, which improved the adsorption kinetics. The latter allowed adequate elasticity values to be reached more quickly. These properties are reached faster for the higher molecular weight chitosan (lower degree of deacetylation), due to the more hydrophobic character that facilitates the interactions between the adsorbed aggregates. Surface rheology revealed a predominantly elastic behaviour of chitosan film. All of these results strengthen the idea that chitosan behaves as a surface-active hydrophilic Pickering agent.

Utilization of Nanochitosan as Adsorbent of Mercury (Hg) in Gold Ore Processing Waste

Mercury pollution in gold ore processing wastewater can cause environmental and health problems. A large amount of mercury pollution causes neurological disease, paralysis, loss of sense of taste, irregular speech, and death. One effective method to reduce mercury amount in the environment is adsorption. Adsorption performance is affected by several factors such as surface area of material, deacetylation degree (DD), and adsorption condition, which is indicated by contact time and mercury concentration. Nanochitosan is used in this research. Effect of deacetylation degree (85%; 87%; 95%), contact time (30;60;90;120 minutes), and variation of mercury concentration (5;10;15;20;25;30 ppm) on adsorption performance was investigated in this research. Nanochitosan in this research is characterized by FTIR, SEM-EDX, BET-BJH, and pH PZC. AAS measures adsorption performance in this research. The result shows that nanochitosan, which has the best adsorption performance, is nanochitosan with a deacetylation degree of 95%, at a contact time of 60 minutes, and mercury concentration is 15 ppm.

Effects of deacetylation degree, molecular weight, and preparation method on wet‐adhesive and rheological properties of chitosan as food‐grade adhesive

In this study, the impacts of deacetylation degree and molecular weight on the rheological and adhesive properties of chitosan (CS) including shear viscosity, initial viscosity, and peel strength of tobacco leaves have been studied. The effect of different dissolution solvents such as acetic acid (HAC) and lactic acid (HL) on chitosan adhesives was also investigated. The results revealed that the adhesive properties increased first and then decreased with the increase of deacetylation degree, while chitosan with higher molecular weight showed higher initial adhesiveness and peel strength values. Chitosan sample III with a medium deacetylation degree of 80.5% showed the best adhesion properties with an excellent ability to reduce the total mold and yeast on the surface of tobacco leaves. Sample HL-CS-III showed a lower initial adhesiveness value but a higher peel strength value than sample HAC-CS-III due to its more viscous nature. Overall, chitosan showed great potential to be used as adhesives for cigar wrapping and other food applications. Novelty impact statement The adhesive properties of chitosan molecules with different molecular weights and degrees of deacetylation values are compared. Chitosan with a larger molecular weight and medium deacetylation degree shows maximum initial adhesiveness and peel strength to tobacco leaf. Chitosan dissolved in lactic acid had a higher peel strength value and better mechanical resistance than acetic acid-dissolved chitosan adhesive.

Gelling properties of silver carp surimi incorporated with konjac glucomannan: Effects of deacetylation degree

Effects of konjac glucomannan (KGM) with different deacetylation degrees on silver carp surimi gel properties were studied. As deacetylation degree increased, viscosity, solubility, and water absorption capability of KGM decreased gradually while particle size increased. The gel strength of surimi gel increased with the KGM deacetylation degree up to 50.72% and then significantly decreased. The maximum gel strength was 3.26 times higher than that of surimi gel with native KGM. The relaxation time of immobilized water decreased from 108.22 to 104.70 ms and then increased up to 110.92 ms with the deacetylation degree, while the proportion of the immobilized water increased from 92.74 to 98.59% and then decreased to 97.46%. Water distribution became less uniform as the deacetylation degree exceeded 50.72%. Surimi gel with KGM of a higher deacetylation degree formed a denser microstructure along with a higher dimensional fraction value. However, the microstructure was disrupted and the dimensional fraction value decreased as the deacetylation degree exceeded 50.72%. Chemical interactions including hydrogen bonds, hydrophobic interactions, and cross-linking extent increased with the KGM deacetylation degree up to 50.72% and then gradually decreased. The results suggest that KGM with a deacetylation degree of 50.72% is the most suitable for surimi products.

Effect of deacetylation degree on properties of Chitosan films using electrostatic spraying technique

Chitosan (CH) films at 4.4 kDa with different deacetylation degree (DD, 81.0, 88.1 and 95.2%) and concentration (0.9, 1.2 and 1.5%) were prepared using electrostatic spraying (ES) system. The effects of DD and concentration on film-forming solution properties, ES-atomization effects, and film performances were investigated. Results indicated that surface tension and viscosity of CH solution declined with the increase of DD, while solution conductivity displayed the opposite trend. The spray angles of film-forming solution during ES were in the range of 10.6–14.2°, and the average median diameters of droplet sizes were all ranged from 6.4 to 13.9 μm. The spray angle and droplet size generally reduced with increasing DD, and thus more complete, rougher and more crystalline microstructures of CH films were observed by SEM, AFM and XRD. CH films at 88.1 and 95.2% DD had better water barrier property and tensile strength. In addition, antibacterial capacities of CH films against L.innocua and E. coli were enhanced with DD. The results could provide guidance on the application of ES technology to improve the commercial food safety such as, fruits, vegetables, poultry, meat, and seafood.

Binding efficacy and kinetics of chitosan with DNA duplex: The effects of deacetylation degree and nucleotide sequences

The binding process of DNA duplex with various types of chitosan polymers were studied at atomic level through molecular dynamics simulations. The interaction kinetics and binding strength, complex morphology and DNA structure evolution were systematically accessed. The binding efficacy of chitosan to DNA reduces (both in complexation speed and binding strength) when deacetylation degree is decreased, because protonated amine groups on chitosan backbone are more prone to bind with DNA, especially the phosphate oxygen, through coulomb interaction. The Watson Crick hydrogen bonds of A-T base pairs are more easily to break because chitosan is capable to form competitive hydrogen bonds with them. It is surprising to find that the G-C nucleotides have highly restrained kinetic motion than that of A-T nucleotides, which would be important for DNA-chitosan complexation and condensation to happen at the microscopic level. From our current results, the degree of chitosan deacetylation is found to play a certain role in regulating the DNA-chitosan complexation process, but is not as important as being believed before. Other types of chemical functionalization that can tune the chitosan’s hydrophobicity should deserve more attentions in the experiment.

Use of Chitosan with Different Deacetylation Degrees for the Adsorption of Food Dyes in a Binary System

Chitosan with different deacetylation degrees was applied for the adsorption of food dyes (Acid Blue 9 and Food Yellow 3) in a binary aqueous system. The effects of deacetylation degree (DD) and pH on the food dyes adsorption were evaluated by response surface methodology (RSM). In the more adequate adsorption condition, the equilibrium curves were obtained under different temperatures, and the extended Langmuir model was fitted to the experimental data. RSM results showed that the best conditions for the adsorption of food dyes onto chitosan were DD of 95% and pH 2.5. Under these conditions, the adsorption capacities were 163.6 and 193.4 mg/g for Acid Blue 9 and Food Yellow 3, respectively. The total percentage removal was 90%. The equilibrium curves were of high affinity (H type) and the adsorption was favored by the temperature decrease. The extended Langmuir model presented satisfactory fit with the experimental equilibrium data. These results demonstrated that chitosan is an efficient adsorbent to remove dyes from binary systems.

Effect of Deacetylation Degree in Chitosan Composite Membranes on Pervaporation Performance

ABSTRACT The effect of the degree of deacetylation in chitosan composite membranes on their pervaporation performance for ethanol dehydration was investigated. The degree of deacetylation of chitosans was measured by using an infrared spectroscopic method and elemental analysis. The chitosan composite membranes were prepared by coating a chitosan solution onto a microporous polyethersulfone membrane with 3–7 nm pore sizes. Then the surface of the top layer (chitosan) of well-dried membranes was crosslinked with sulfuric acid, and pervaporation experiments for binary mixtures (water—ethanol) were carried out at various conditions. In the case of a chitosan membrane with a high degree of deacetylation, the flux increases while the separation factor decreases compared with membranes with a low degree of deacetylation.