Physicochemical Characteristics Of Chitosan Research Articles

Physicochemical characteristics of chitosan from swimming crab (Portunus trituberculatus) shells prepared by subcritical water pretreatment

The physicochemical properties of chitosan obtained from the shells of swimming crab (Portunus trituberculatus) and prepared via subcritical water pretreatment were examined. At the deacetylation temperature of 90 °C, the yield, ash content, and molecular weight of chitosan in the shells prepared via subcritical water pretreatment were 12.2%, 0.6%, and 1187.2 kDa, respectively. These values were lower than those of shells prepared via sodium hydroxide pretreatment. At the deacetylation temperature of 120 °C, a similar trend was observed in chitosan molecular weight, but differences in chitosan yield and ash content were not remarkable. At the same deacetylation temperature, the structures of chitosan prepared via sodium hydroxide and subcritical water pretreatments were not substantially different. However, the compactness and thermal stability of chitosan prepared via sodium hydroxide pretreatment was lower than those of chitosan prepared via subcritical water pretreatment. Compared with the chitosan prepared by sodium hydroxide pretreatment, the chitosan prepared by subcritical water pretreatment was easier to use in preparing oligosaccharides, including (GlcN)2, via enzymatic hydrolysis with chitosanase. Results suggested that subcritical water pretreatment can be potentially used for the pretreatment of crustacean shells. The residues obtained via this method can be utilized to prepare chitosan.

Optimization and Physicochemical Characterization of Chitosan and Chitosan Nanoparticles Extracted from the Crayfish Procambarus clarkii Wastes

The main objective of this study was to allocate and evaluate the most optimum condition to prepare the chitosan and chitosan nanoparticles that will, subsequently, give the best physicochemical characterization regarding the nanoparticles' size and surface morphology. Chitosan from the exoskeleton wastes of Procambarus clarkii with degree of deacetylation 87% was extracted. Viscometry indicated that the obtained chitosan had a low molecular weight that can be useful in many applications. Chitosan nanoparticles were prepared by using different concentrations of chitosan and the polyanion sodium tripolyphosphate (TPP). For the determination of the optimum condition for the prepared chitosan nanoparticles, three different ratios of chitosan to the polyanion TPP were used, 1:1, 3:1, and 1:3. A novel nanoparticle system composed of low molecular weight chitosan was successfully prepared by the ionotropic gelation technique under an aqueous-based condition. The physicochemical characteristics of chitosan and chitosan nanoparticles were elucidated by Fourier-transform IR spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis, scanning electron microscopy, transmission electron microscopy, and zeta potential. The best physicochemical characteristics were obtained by adding chitosan to TPP in a ratio of 1:1. The small particle size and narrow range distribution of the obtained chitosan nanoparticles may increase their chance for easy and efficient manipulation for several applications in various fields. In addition, the obtained positively charged chitosan nanoparticles can be used for the delivery of negatively charged compounds.

Chitosan in Biology, Microbiology, Medicine, and Agriculture

The mini-review deals with the recent developments in investigation and application of chitosan and its derivatives within a broad range of human activities. A short historical note on discovery of chitin and chitosan is provided. Special attention is paid to chitosan occurrence and structure, as well as to antimicrobial properties of this biopolymer and their dependence upon the physicochemical characteristics of chitosan: its molecular mass and deacetylation degree, and the conditions of derivative formation. The possible mechanisms of chitosan biological activity are briefly considered.

Effect of physical and physicochemical characteristics of chitosan on fat-binding capacities under in vitro gastrointestinal conditions

The correlation of physical and physicochemical characteristics of five different chitosan on their fat-binding capacities was studied using in vitro model of gastrointestinal conditions. Increasing molecular weight (Mw) and tap density of chitosan could significantly increase their fat-binding ability. Higher Mw chitosan (2100 and 890 kDa) show significantly higher fat binding capacity than 30 kDa. When tested at chitosan to fat 1:40, the ratio often used as dietary supplement, higher tap density chitosan showed an improved fat-binding capacity at around 2-fold increase. Interestingly, 2100 kDa high density (HD1P) could maintain the highest oil entrapment, ranging between 0.77 and 27.50 g oil/g chitosan depending on the interaction ratios. In addition, HD1P already maximized its fat-binding capacity since 30 min under in vitro gastric condition. In vitro cholesterol- and bile acids-binding experiments were also performed with HD1P and found to bind cholesterol at 820.9 ± 21.43 mg/g chitosan, deoxycholic acid at 17.50 ± 0.18 mg/g chitosan, and cholic acid at 5.28 ± 0.57 mg/g chitosan. Therefore, this study shows that the ability of HD1P for binding high amount of fat at short dissolution time might be due to the combination characteristics of having high Mw and being in a high density form.

The calcium-dependent regulation of spheroid formation and cardiomyogenic differentiation for MSCs on chitosan membranes

Mesenchymal stem cells (MSCs) were recently found to form three-dimensional (3D) multicellular spheroids on chitosan membranes. The exact mechanism of spheroid formation, however, remains unclear. In this study, the regulation of spheroid formation for adipose derived adult stem cells (ADAS) grown on chitosan membranes was examined. By varying the membrane thickness, calcium concentration in culture medium, and acetylation extent of chitosan, the physico-chemical characteristics of chitosan that modulated spheroid formation was elucidated. The capacity of cardiomyogenic differentiation was further evaluated. Results suggested that the calcium binding capacity of chitosan may affect the cell–substrate and cell–cell interactions and critically influence the dynamics of spheroid formation. The intracellular calcium level was elevated for ADAS spheroids on chitosan. Chitosan-bound calcium was observed to enter the cells. The expression of N-cadherin was upregulated for ADAS spheroids on chitosan, evidenced by quantitative RT-PCR and Western blot. After the induction by 5-aza, the expression levels of cardiac marker genes (Gata4, Nkx2.5, Tnnt2, and Myh6) were remarkably enhanced (about four-fold) for ADAS on chitosan vs. tissue culture polystyrene or polyvinyl alcohol. Immunofluorescence staining confirmed the expression of cardiac-associated tight junction protein ZO-1 for ADAS grown on chitosan membranes. The gene expression of Wnt11 was significantly upregulated for ADAS spheroids on chitosan at 3 days and 12 days. We suggested that Wnt11 may be involved in the spheroid formation and cardiomyogenic differentiation of MSCs on chitosan membranes. Spheroids formed on the acetylated chitosan or polyvinyl alcohol membranes failed to show such behavior. The properties of MSC spheroids were therefore determined by the culture substrate.

Antibacterial activity of products of depolymerization of chitosans with lysozyme and chitosanase against Campylobacter jejuni

Chitosan has several biological properties useful for the food industry, but the most attractive is its potential use as a food preservative of natural origin due to its antimicrobial activity against a wide range of food-borne microorganisms. Among food-borne pathogens, Campylobacter jejuni and related species are recognised as the most common causes of bacterial food-borne diarrhoeal disease throughout the world. Recently, it has been demonstrated that campylobacters are highly sensitive to chitosan. Even though chitosan is known to have important functional activities, poor solubility makes them difficult to use in food and biomedical applications. Unlike chitosan, the low viscosity and good solubility of chitosan oligosaccharides (COS) make them especially attractive in an important number of useful applications. In the present work, the effect of different COS on C. jejuni was investigated. Variables such as the physicochemical characteristics of chitosan and the enzyme used in COS preparation were studied. The COS had been fractioned using ultrafiltration membranes and each fraction was characterized regarding its F A and molecular weight distribution. It has been demonstrated that the biological properties of COS on Campylobacter depend on the composition of the fraction analysed. COS prepared by enzymatic hydrolysis with chitosanase were more active against Campylobacter that lysozyme-derived COS, and this behaviour seems to be related with the acetylation of the chains. On the other hand, the 10–30 kDa fraction was the most active COS fraction, independently of the enzyme used for the hydrolysis. These results have shown that COS could be useful as antimicrobial in the control of C. jejuni.

Investigation of different natural sources of chitin: influence of the source and deacetylation process on the physicochemical characteristics of chitosan

Several sea sources for chitin have been investigated, and the chitin content and crystallographic polymorph of the extracted chitin determined. Deacetylation of the chitin was carried out and the physicochemical characteristics of the resulting chitosan studied. The influence of the reaction parameters (reaction duration, temperature, nature of alkaline reagent, etc) was followed. Thus it became possible to determine adequate reaction conditions for obtaining chitosans with the required properties. The physicochemical characteristics of the obtained chitosan are closely related to the taxonomy of the source. New sea sources for chitin have been investigated and considered for industrial purposes. © 2000 Society of Chemical Industry

On the influence of deacetylation process on the physicochemical characteristics of chitosan from squid chitin

Chitin was extracted from squid pens and the used conditions allow to obtain a completely N-acetylated β-chitin with a molecular weight large enough for the obtention of chitosans of high molecular weight. Deacetylation, leading to the obtention of chitosan, was performed according to two processes (Kurita and Broussignac conditions) and the physicochemical characteristics (degree of acetylation and molecular weight) of the obtained chitosans were compared. The influence of the reaction conditions (temperature, repetition of alkaline steps, etc.) is discussed in relation with the physicochemical characteristics of the chitosan. This will allow one to choose the best process for preparing chitosan so that it is suitable for its end use.