Viscosity Of Chitosan Research Articles

An ultrasensitive electrochemical sensor for detecting Cd(II) in aquatic products based on CS/COFs/PEDOT: PSS modified acupuncture needle electrode

The use of low-cost working electrodes is of great importance for the development of sensor industrialization. Acupuncture needles electrode (ANE) was selected as working microelectrode, a sensor was designed based on poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT: PSS) and chitosan (CS) modified covalent organic frameworks (COFs) (CS/COFs) for detection of cadmium (Cd(II)). First, a mixture of PEDOT and PSS was electrodeposited on the surface of the acupuncture needles to synthesize a PEDOT: PSS as conductive polymeric film to support the electron transfer capability and enhance the conductive efficiency of the sensor. Then, CS/COFs was self-assembled and attached to the PEDOT: PSS/ANE surface by π-π stacking intermolecular interaction forces and the viscosity of CS, thus increasing the specific surface area of the electrode. Differential pulse anodic stripping voltammetry (DPASV) was used as the electrochemical method for detection of Cd(II). And the results indicated that the CS/COFs/PEDOT: PSS/ANE was linearly responsive in the range of 400 μg/L to 2400 μg/L, and the LOD was 13.8 ng/L for Cd(II). The constructed sensor also showed great selectivity, reproducibility, and stability. Additionally, the sensor demonstrated outstanding recovery in the detection of Cd(II) in real sample scallops. This sensing construction method based on acupuncture needles as working electrodes is of great significance to the development of sensor industrialization and aquatic product safety detection.

Improving the technology for obtaining of low molecular weight chitosan under conditions of controlled enzymatic cleavage

Relevance. Annotation. Experimental data on improving the production technology of regulated enzymatic cleavage of chitosan to obtain its low-molecular derivatives are presented. Experimental studies were carried out in the conditions of the Department of Disease Diagnostics, Therapy, Obstetrics and Animal Reproduction of the Moscow State Academy of Veterinary Medicine and Biotechnology — MVA named after K.I. Skryabin and on the basis of the All-Russian Research and Technological Institute of the Biological Industry.Methods. Acid-soluble chitosan from king crab shell (MM 700 kDa, SDA 85%), chitosan succinate (MM 330 kDa, SZ 75.2%), low-molecular food chitosan (hydrochloride) (MM 50 kDa) were used as raw materials for obtaining new modifications of chitosan, gel chitosan (2% solution in 2% acetic acid) manufactured by Bioprogress LLC.Results. As a result of the experiment, the technological parameters of obtaining low-molecular chitosan by enzymatic hydrolysis were selected. The greatest decrease in the dynamic viscosity of chitosan was reliably observed in the pilot-industrial series II (by 29.3 times), and the pilot-industrial series I and III — by 6.9 and 10.6 times, respectively. As a result of enzymatic hydrolysis of chitosan in the pilot series II, it was possible to reduce the molecular weight from 700 to 24 kDa, and in series I and III — to 102 and 66 kDa. Based on the research results, a technological scheme for obtaining low-molecular-weight chitosan derivatives by enzymatic hydrolysis has been developed, tested and proposed for industrial use, technical conditions have been developed.

Pickering Emulsions Stabilized by Chitosan/Natural Acacia Gum Biopolymers: Effects of pH and Salt Concentrations

In this study, chitosan (CT) and naturally occurring acacia gum (AG) blends were employed as emulsifiers to form a series of emulsions developed from diesel and water. Effects of pH level (3, 5, 10, and 12) and various NaCl salt concentrations (0.25-1%) on the stability, viscosity, and interfacial properties of CT-(1%)/AG-(4%) stabilized Pickering emulsions were evaluated. Bottle test experiment results showed that the stability indexes of the CT/AG emulsions were similar under acidic (3 and 5) and alkaline (10 and 12) pH media. On the other hand, the effects of various NaCl concentrations on the stability of CT-(1%)/AG-(4%) emulsion demonstrated analogous behavior throughout. From all the NaCl concentrations and pH levels examined, viscosities of this emulsion decreased drastically with the increasing shear rate, indicating pseudoplastic fluid with shear thinning characteristics of these emulsions. The viscosity of CT-(1%)/AG-(4%) emulsion increased at a low shear rate and decreased with an increasing shear rate. The presence of NaCl salt and pH change in CT/AG solutions induced a transformation in the interfacial tension (IFT) at the diesel/water interface. Accordingly, the IFT values of diesel/water in the absence of NaCl/CT/AG (without emulsifier and salt) remained fairly constant for a period of 500 s, and its average IFT value was 26.16 mN/m. In the absence of salt, the addition of an emulsifier (CT-(1%)/AG-(4%)) reduced the IFT to 16.69 mN/m. When the salt was added, the IFT values were further reduced to 12.04 mN/m. At low pH, the IFT was higher (17.1 mN/M) compared to the value of the IFT (10.8 mN/M) at high pH. The results obtained will help understand the preparation and performance of such emulsions under different conditions especially relevant to oil field applications.

AuNP/Chitosan Nanocomposites Synthesized through Plasma Induced Liquid Chemistry and Their Applications in Photothermal Induced Bacteria Eradication.

In this work, a facile direct current atmospheric pressure micro-plasma (APM) technology was deployed for the synthesis of functional gold nanoparticle/chitosan (AuNP/CS) nanocomposites for the first time. Different experimental parameters, such as metal salt precursor concentration and chitosan viscosity, have been investigated to understand their effects on the resulting nanocomposite structures and properties. The nanocomposites were fully characterized using a wide range of material characterization techniques such as UV–vis, transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS) analyses. Potential reaction pathways have been proposed for the nanocomposite synthesis process. Finally, potential of the synthesized nanocomposites towards photothermal conversion and bacteria eradiation applications has been demonstrated. The results show that APM is a facile, rapid and versatile technique for the synthesis of AuNP/CS functional nanocomposites. Through this work, a more in-depth understanding of the multi-phase system (consisting of gas, plasma, liquid and solid) has been established and such understanding could shine a light on the future design and fabrication of new functional nanocomposites deploying the APM technique.

Characterization and Optimization of Chitosan-Coated Polybutylcyanoacrylate Nanoparticles for the Transfection-Guided Neural Differentiation of Mouse Induced Pluripotent Stem Cells.

Gene transfection is a valuable tool for analyzing gene regulation and function, and providing an avenue for the genetic engineering of cells for therapeutic purposes. Though efficient, the potential concerns over viral vectors for gene transfection has led to research in non-viral alternatives. Cationic polyplexes such as those synthesized from chitosan offer distinct advantages such as enhanced polyplex stability, cellular uptake, endo-lysosomal escape, and release, but are limited by the poor solubility and viscosity of chitosan. In this study, the easily synthesized biocompatible and biodegradable polymeric polysorbate 80 polybutylcyanoacrylate nanoparticles (PS80 PBCA NP) are utilized as the backbone for surface modification with chitosan, in order to address the synthetic issues faced when using chitosan alone as a carrier. Plasmid DNA (pDNA) containing the brain-derived neurotrophic factor (BDNF) gene coupled to a hypoxia-responsive element and the cytomegalovirus promotor gene was selected as the genetic cargo for the in vitro transfection-guided neural-lineage specification of mouse induced pluripotent stem cells (iPSCs), which were assessed by immunofluorescence staining. The chitosan-coated PS80 PBCA NP/BDNF pDNA polyplex measured 163.8 ± 1.8 nm and zeta potential measured −34.8 ± 1.8 mV with 0.01% (w/v) high molecular weight chitosan (HMWC); the pDNA loading efficiency reached 90% at a nanoparticle to pDNA weight ratio of 15, which also corresponded to enhanced polyplex stability on the DNA stability assay. The HMWC-PS80 PBCA NP/BDNF pDNA polyplex was non-toxic to mouse iPSCs for up to 80 μg/mL (weight ratio = 40) and enhanced the expression of BDNF when compared with PS80 PBCA NP/BDNF pDNA polyplex. Evidence for neural-lineage specification of mouse iPSCs was observed by an increased expression of nestin, neurofilament heavy polypeptide, and beta III tubulin, and the effects appeared superior when transfection was performed with the chitosan-coated formulation. This study illustrates the versatility of the PS80 PBCA NP and that surface decoration with chitosan enabled this delivery platform to be used for the transfection-guided differentiation of mouse iPSCs.

Equipment-free quantitative determination of urea based on paper-based sensor via urease-mediated chitosan viscosity change

In this study, a paper-based sensor combined with visual distance-readout technique for point of-care testing (POCT) of urea was developed by urease-mediated chitosan viscosity change. A series of factors that affect the performance of the sensor were investigated, including the type of filter paper, chitosan concentration, acetic acid concentration and enzymatic reaction conditions. Under optimal conditions, the proposed method for urea determination has good linearity between 3.8–15.1 mM. The limit of quantitation is 3.8 mM. Finally, the paper-based sensor was successfully applied to the determination of urea in two diesel exhaust fluid (DEF) samples. The recoveries of urea were 91.4 % and 109.9 % in DEF-1 and DEF-2, respectively. The present study provides a novel approach, which integrates paper-based sensor and visual distance-readout technique, for monitoring urea in POCT application, especially in remote or resource-limited regions.

Screening acetylcholinesterase inhibitors from traditional Chinese medicines by paper-immobilized enzyme combined with capillary electrophoresis analysis

Discovering acetylcholinesterase (AChE) inhibitors is one of the important ways to develop new drugs for the treatment of Alzheimer's disease. In this work, a simple strategy was developed for screening AChE inhibitors from traditional Chinese medicines (TCMs) by capillary electrophoresis (CE) analysis combined with enzymatic assay, in which immobilized AChE was employed. For AChE immobilization, cellulose filter paper (CFP) was used as the carrier material and physically coated with chitosan owing to moderate viscosity of chitosan to be introduced into amino groups, and then AChE was covalently bonded to the amino-functionalized CFP through a Schiff base reaction using glutaraldehyde (GA) as a cross-linking agent. The CFP-immobilized AChE exhibited enhanced endurance to pH and temperature, improved storage stability, excellent repeatability and reusability. More remarkably, CFP-immobilized AChE can be instantly separated from enzyme reaction mixture thus greatly simplifying the operational process. For immobilized AChE, the Michaelis-Menten constant, inhibition constant and IC50 were determined using huperzine A as a model inhibitor. Finally, CFP-immobilized AChE was applied to inhibitor screening from 17 TCMs, among which Chebulae Fructus (ripe fruits of Terminalia chebula) exhibited the strongest inhibitory effect on AChE. The positive results indicated that such a screening strategy may open up a new avenue to discover active components from TCMs.

Effective gamma irradiation dose on viscosity and molecular weight reduction of chitosan

Chitosan is a potential natural blood lead chelating agent. In order to improve its chelating capability, the solubility of chitosan must be enhanced. It is an essential property which is also closely related to molecular weight and viscosity. One of the most renowned and effective methods to reduce the molecular weight and viscosity of a certain particle is irradiation. This research aims to examine the effect of Gamma 60Co irradiation upon molecular weight and viscosity of chitosan. 80 mesh chitosan was irradiated using Gamma 60Co with different doses (0, 50, 100, and 150 kGy). This process was carried out using gamma irradiator in the Centre of Isotopes and Radiation Application at BATAN (National Nuclear Energy Agency). Viscosity and molecular weight measurements were conducted using the viscosimetric method in the chemistry laboratory of FMIPA UNNES, while molecular weight was calculated using the Mark-Houwink equation. Results showed that the specific viscosity of chitosan decreased after the irradiation process from the initial specific viscosity of 4.98 η (0 kGy dose) to 3.28 η (50 kGy), 2.87 η (100 kGy), and 2.09 η (150 kGy). A similar trend was also found in the molecular weight of chitosan from the initial molecular weight of 2.10×105 kDa (0 kGy dose) to 1.25×105 kDa (50 kGy), 1.04×105 kDa (100 kGy), and 5.72 × 104 kDa (150 kGy). It was concluded that Gamma Co60 irradiation decreases the viscosity and molecular weight of chitosan by the effective dose of 150 kGy.

Effect of deacetylation degree of chitosan on rheological properties and physical chemical characteristics of genipin-crosslinked chitosan beads

The effect of the degree of deacetylation (DD) on the characteristics of the support matrix formed through chitosan (CH) and genipin (GE) crosslinking was investigated by using CH with DD of 83, 94 and 96%. The rheological properties of CH dispersions were determined in order to study the influence of DD on the CH viscosity, gel network structures and gelation temperature (Tgel). The CH exhibited the shear-thinning behavior of pseudoplastic fluids. Tgel decreased with the increase of DD and the sol-gel transition temperature of CH-83, CH-94 and CH-96 were 75, 30 and 25 °C, respectively. The magnitude of viscous modulus (G’’) was higher than the elastic modulus (G’), revealing the formation of a weak gel structure. The CH dispersions have been used in the preparation of beads and then crosslinked with GE to form support matrices. Besides, to verify how it influences in a practical application, an enzymatic immobilization was carried out using a β-d-galactosidase (BG) as a model, which could be advantageously employed to promote hydrolysis of lactose. Scanning Electron Microscope images showed biocatalysts with multiple porous compartments. Fourier Transform Infrared Spectroscopy (FTIR) analyses confirmed chemical and physical interactions between CH, GE and BG. Thermogravimetric analysis (TGA) demonstrated that the DD of CH had a positive influence in the thermal degradation behavior of the biocatalysts up to 200 °C, which represents the temperature range used in most enzymatic reactions (up to 100 °C) in the industrial scale applications.

Viscosity of chitosan impacts the efficacy of F/Sn containing toothpastes against erosive/abrasive wear in enamel

ObjectivesChitosan (Ch) in F/Sn-toothpastes can increase toothpastes’ anti-erosive efficacy. Whether efficacy can be further increased by changing chitosan’s viscosity was study aim. Methods192 human enamel specimens were assigned to 2 × 6 groups (n = 16 each): Four F/Sn (500 ppm F−, 800 ppm Sn2+) toothpastes with chitosan (0.5 %, viscosity 50, 500, 1000 or 2000 mPas), negative-control (no F/Sn/chitosan), positive-control (F/Sn, no chitosan). The study was conducted in two experiments (E1/E2). Specimens were cyclically demineralised (10 d, 6 × 2 min/d; 0.5 % citric acid); half of groups (E1) was exposed to toothpaste slurries (2 × 2 min/d), the other half was additionally brushed (2 × 15 s/d, E2). Tissue loss (mean ± SD, μm) was quantified profilometrically. Element analysis (EDX, wt%) on specimen surfaces and on toothpastes’ particulate fraction and SEM analysis of specimen surfaces were performed. ResultsTissue loss in negative-controls (E1/E2) was 4.96 ± 1.55/12.76 ± 2.45. Toothpastes with active agents (AA) reduced tissue loss compared to negative-control (p < 0.0001). E1: All AA caused precipitates, being the thickest after Ch500. Chitosan increased carbon retention, not tin retention. E2: Only Ch1000 increased efficacy (-0.97 ± 4.48) compared to positive-control (2.98 ± 1.32; p = 0.05). EDX showed comparable carbon values in all AA; tin content was higher in Ch1000 (6.5 ± 3.4) compared to other AA (range: 3.8 ± 0.3–4.3 ± 1.3). On abrasives, tin adsorption was decreased by all chitosans. SEM revealed minor structural differences. ConclusionsChitosan viscosity has impact on efficacy of F/Sn toothpastes. Under erosive/abrasive conditions Ch1000 showed the best protective effect with higher tin retention on surfaces and lower tin absorption by abrasives. Clinical significanceThe biopolymer chitosan shows protective effect against enamel erosion and erosion/abrasion when used in an F/Sn toothpaste with specific viscosity.

Effect of re-acetylation on the acid hydrolysis of chitosan under an induced electric field

This study explored the impact of re-acetylation on induced electric field (IEF)-assisted hydrolysis of chitosan. Chitosan with different degree of deacetylation (DD) exhibited different charge content but similar electrical conductivity and output voltage of the electrolyte system, thus theoretically resulting in equivalent electro-processing efficiency. However, molecular and rheological measurements suggested that the hydrolysis rate decreased with an increase of DD. Re-acetylation had no significant effect on the molecular weight and viscosity of chitosan but damaged its granular and crystal structure, making chitosan chains more susceptible to the acid. The IEF-assisted hydrolysis of dissolved chitosan confirmed that the structural compactness of chitosan played a more important role on the hydrolysis than the charge content. This study extended current knowledge regarding the effect of charge content and structural compactness on IEF-assisted hydrolysis process, which contributed to the applications of IEF in biopolymer modification.

Chitosan/glyphosate formulation as a potential, environmental friendly herbicide with prolonged activity

Although there are many reports on the dangers posed by glyphosate, this herbicide is still one of the most popular and widely used total weed killers. Therefore, great effort should be made to minimize exposure to this herbicide and limit its losses into the environment. The aim of this study was to prepare a new formulation consisted of various molecular weight chitosans with glyphosate and their evaluation toward active substance release, phytotoxicity, and preliminary herbicidal efficiency. The phytotoxicity study of the obtained chitosan/glyphosate formulations was determined based on the Organisation for Economic Co-operation and Development 208 guideline. Among all tested formulations evaluated for phytotoxicity, that containing the highest molecular weight of chitosan was found to be the least toxic, showing simultaneously the most effective herbicidal activity against selected weeds. The release rate of glyphosate from the obtained formulations was dependent on the molecular weight and viscosity of chitosan.

Perspectives of chitosan nanofiber/film scaffolds with bone marrow stromal cells in tissue engineering and wound dressing

Objective (s): Several methods have been proposed for repairing defects and damages, one of which is cell therapy. Bone marrow stromal cells seem to be suitable for this purpose. On the other hand, many biometric materials are used to improve and correct the defects in the body. Nanofibers are widely used in the medical industry, especially in tissue engineering, as scaffolds in wound healing and wound dressing. Chitosan/polyethylene oxide nanofibers can be a suitable replacement for routine wound coverages. Hence, this study was conducted to present a combination of these methods.Materials and Methods: Chitosan/polyethylene oxide nanofibers and thin films of chitosan were produced and optimized by electron microscopy, on which the bone marrow stromal cells were then cultivated. Interactions between the cells and these biomaterials were investigated through viability, morphology, immunocytochemistry and electron microscopy of cells after 6 days. All data were analyzed using Student’s t-test and one-way ANOVA tests in SPSS version 16. PResults: It seems that the high viscosity of chitosan prevents the formation of nanofibers, while chitosan/polyethylene oxide solutions with 80/20 and 90/10 ratios produce perfect, regular, bead free and non-toxic nanofibers with average diameter of 240±10 and 220±10 nm, respectively. The results of immunocytochemistry and viability showed that the cells had relatively high proliferation on the thin chitosan membranes, while the results of the electron microscopy showed that the morphology of cells was better on the nanofibers than on the thin membrane of chitosan.Conclusion: Since bone marrow stromal cells were grown well on chitosan-nanofibers, each of them alone was used in the therapeutic methods. It is better to consider a combination of two methods as the treatment method, especially in tissue engineering and cell therapy.

Extraction of chitin and chitosan from larval exuvium and whole body of edible mealworm, Tenebrio molitor

AbstractThe purpose of this study was to investigate the production of chitin and chitosan from both the exuvium and whole body of mealworm (Tenebrio molitor) larvae. Chitin from the exuvium and whole body of T. molitor larvae was chemically extracted with acid and alkali solutions to achieve demineralization (DM) and deproteinization (DP), respectively. The average DM (%) and DP (%) on a dry weight (DW) basis was 32.56 and 73.16% from larval exuvium, and 41.68 and 91.53% from whole body, respectively. To obtain chitosan, chitin particles from the exuvium and whole body of T. molitor larva were heated at various temperatures in different concentrations of NaOH. Average chitin yields were 18.01% and 4.92% of DW from the exuvium and whole body, respectively. The relative average yield of chitosan from whole body was 3.65% of DW. On average, over 90% of chitosan derived from whole body was deacetylated. The viscosity of chitosan from whole body was ranged from 48.0 cP to 54.0 cP. The chitin content of dry and wet byproducts from whole body were 17.32% and 16.94% respectively, compared to dry weight. The chitosan contents of byproducts on a DW basis were 14.48% in dry and 13.07% in wet byproduct. These results indicate that the exuvium and whole body of T. molitor larva may serve as a source of chitin and chitosan for use in domestic animal feed.

KEEFEKTIFAN KITOSAN DALAM MENGENDALIKAN Botryodiplodia theobromae Pat. PENYEBAB MATI PUCUK PADA BIBIT JABON (Anthocephalus cadamba (Roxb.) Miq) Chitosan’s Effectiveness in Controlling Dieback by Botryodiplodia theobromae Pat on Jabon Seeding

Dieback disease by the fungus Botryodiplodia theobromae in Jabon seedlings (Anthocephalus cadamba) inhibits the regeneration of Jabon plant. Synthetic fungicides utilization to several problems such as residue on the environment and pathogen resistance. Chitosan is a potential natural compound used as an alternative to control plant disease.This research aims to examine the effectiveness of chitosan to control B. theobromae as causal agent of dieback on Jabon seedlings and to examine the effect of chitosan to control the viscosity of dieback disease on Jabon seedlings. The results showed that the chitosan solution can decrease the severity of disease in Jabon seedlings. However, it was different with the disease incidence rate parameter. Chitosan solution was not significantly affecting the disease because B. theobromae caused dieback symptoms on Jabon seedlings. The most effective treatment was chitosan solution with a concentration of 0.1% before inoculation with the severity of the disease by 25%. Chitosan solution viscosity was responsible in affecting the percentage of dieback disease in Jabon seeds. The higher the viscosity of chitosan, the higher the percentage of dieback disease attacks. The best viscosity to suppress the development of dieback disease on Jabon seedlings was 8.80 with 7.90% attack.Key words: Anthocephalus cadamba , Botryodiplodia theobromae, chitosan, dieback.

Extraction of Chitin and Chitosan from the Exoskeleton of the Cockroach (Periplaneta americana L.)

Chitin and chitosan from the exoskeleton of the cockroach (Periplaneta americana L.) were extracted using the following chemical treatment with an acid and alkali: For chitin extraction, 2 N HCl and 1.25 N NaOH solutions were used to achieve demineralization and deproteinization, respectively. To obtain chitosan, chitin particles from cockroaches were boiled at different NaOH concentrations and temperatures. The relative average yields of chitin and chitosan from cockroaches were 3.36% and 2.08%, respectively, on a fresh-weight basis. The relative average yield of chitin and chitosan was 12.17% and 7.28%, respectively, on a dry-weight basis. The deacetylation percentage of chitosan from exoskeletons of cockroaches were 90.03%, 91.86%, and 89.4% in Procedures B, C, and D, respectively. The viscosity of chitosan extracted from exoskeletons in Procedures B, C, and D was 48.0, 69.6, and 36.0 cP, respectively. The molecular weight of the obtained chitosan was 230,300 Da in Procedure C and 212,100 Da in Procedure D. Our results indicate that exoskeletons of cockroaches may serve as a source of chitin and chitosan for livestock and cultured fish industry and for preparation of elicitors for improvement of resistance to phytopathogens in agriculture.

Synergistically enhanced stability of laccase immobilized on synthesized silver nanoparticles with water-soluble polymers

Silver nanoparticles (AgNPs) were synthesized by citrate reduction method in the presence of polymers, poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and chitosan, used as stabilizing agents, and an oxidoreductase enzyme, laccase (Lac), with the goal of expanding the NPs antimicrobial action.AgNPs were characterized by UV–vis spectrometry, dynamic light scattering and transmission electron microscopy. As protecting agents, PEG and PVA promoted the formation of spherical uniformly-shaped, small-sized, monodispersed AgNPs (≈20nm). High Mw polymers were established as most effective in producing small-sized NPs. Chitosan's viscosity led to the formation of aggregates. Despite the decrease in Lac activity registered for the hybrid formulation, AgNPs-polymer-Lac, a significant augment in stability over time (up to 13days, at 50°C) was observed. This novel formulation displays improved synergistic performance over AgNPs-Lac or polymer-Lac conjugates, since in the former the Lac activity becomes residual at the end of 3days. By enabling many ionic interactions, chitosan restricted the mass transfer between Lac and substrate and, thus, inhibited the enzymatic activity.These hybrid nanocomposites made up of inorganic NPs, organic polymers and immobilized antimicrobial oxidoreductive enzymes represent a new class of materials with improved synergistic performance. Moreover, the Lac and the AgNPs different antimicrobial action, both in time and mechanism, may also constitute a new alternative to reduce the probability of developing resistance-associated mutations.

On the possibility of regulating the rate of enzymatic destruction of chitosan in an acetic acid solution

The enzymatic destruction of chitosan in an acetic acid solution in the presence of sodium chloride and sulfate was considered. It was shown that the addition of these low-molecular electrolytes is accompanied by a tightening of the macromolecular coil, as indicated by a decrease in the α constant in the Mark–Kuhn–Houwink equation and the intrinsic viscosity of chitosan. As a consequence, the chitosan units become less accessible for interaction with the enzyme, and the kinetic parameters of the process (Michaelis constant K M and the maximum rate of enzymatic destruction V max) change accordingly. This suggests that the resistance of this polymer to the enzyme action can be enhanced by introducing low-molecular electrolyte salts in the solution or film coating to suppress the polyelectrolyte swelling of chitosan.

Some Approaches to Viscometric Study of Chitosan in Acetic Acid Solution

Some ways of estimating the values of the intrinsic viscosity of chitosan were analyzed. It was shown that the method of Irzhak and Baranov for estimating the current value of the intrinsic viscosity allows to adequately estimates the conformational state of the macromolecular coil and its degree of swelling.

Evaluation of structural and functional properties of chitosan⿿chlorogenic acid complexes

The objectives of the present study were to first synthesize chitosan⿿chlorogenic acid (CA) covalent complex and then compare structural and functional properties between chitosan⿿CA covalent complex and physical complex. First, chitosan⿿CA covalent complex was synthesized and its total phenolic content was as high as 276.5±6.2mg/g. Then structural and functional properties of chitosan⿿CA covalent and physical complexes were analyzed. The covalent reaction induced formation of both amide and ester bonds in chitosan. Data of X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the complexations of CA changed crystallinity and morphology of chitosan, and covalent complexation induced a larger change of physical structure than physical complexation. In terms of functional properties, chitosan⿿CA covalent complex exhibited better thermal stability than physical complex in terms of antioxidant activity, and the viscosity of chitosan was significantly increased by covalent modification.