Lower Degree Of Deacetylation Research Articles

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.

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.

Chitosan Films Prepared with Low Nanometal Content for Developing Protective Denim Fabrics

At this study; Chitosan was obtained from crayfish and identified by X-ray diffraction (XRD), molecular weight and elemental analyses. Later, it was coated on fabrics alone and in combination with nano-metal.The protective properties of the coated fabrics was investigated by UV protection and antibacterial analyses. Crayfish chitosan had low crystallinity (72%), low molecular weight (Mw) (11.2 kDa) and low degree of deacetylation (DD) (16%). When used together, nano-TiO2 reduced the UVprotection of the crayfish chitosan in both dyed and undyed denim fabrics.Chitosan+Nano-Ag coated fabric had the highest antibacterial activity (Antibacterial activity value (A): 4.27) against Staphylococcus aureus while chitosan+Nano-TiO2 coated fabric did not show any antibacterial efficiency (A: 1.89). Afterwashed, the chitosan coated and the chitosan+Nano-Ag coated fabrics retained their antibacterial efficiency.

KARAKTERISASI KITOSAN KOMBINASI CANGKANG KERANG HIJAU (Perna viridis) DAN CANGKANG RAJUNGAN (Portunus pelagicus) ASAL BANTEN, INDONESIA

Green mussel shells (Perna viridis) and crab shells (Portunus pelagicus) have not been optimally utilized. It’s can be used as chitosan. Chitosan from green mussels has a low degree of deacetylation, so it needs to be combined with crab shells in its manufacture. The aims of this study were to characterize and determine the best combination of raw materials for making chitosan from green mussel shells and crab shells. The method in this study used a completely randomized design with triplicate. The treatment in this study was a combination of raw materials from green mussel shells and crab shells, which were 100:0; 75:25; 50:50% (w/w). The results of this study showed that the combination of green mussel shells and crab shells 50:50% (w/w) resulted the best characterization of chitosan with a yield 12.56%, water content 7.55%, ash content 1.59%, degree of deacetylation 73.96% and viscosity of 279 cP

Effects of Chitosan Molecular Weight and Degree of Deacetylation on Chitosan-Cellulose Nanocrystal Complexes and Their Formation.

This study was conducted to determine the effects of chitosan molecular weight and degree of deacetylation (DD) on chitosan-cellulose nanocrystal (CNC) polyelectrolyte-macroion complexes (PMCs) and their formation. Chitosan samples with three different molecular weights (81, 3 · 103, 6 · 103 kDa) and four different DDs (77, 80, 85, 89%) were used. The effects on PMC formation were determined by turbidimetric titration. An effect of the molecular weight of chitosan was not observed in turbidimetric titrations. Turbidity levels were higher for CNCs with lower sulfate group density and larger hydrodynamic diameter than for CNCs with higher sulfate group density and smaller hydrodynamic diameter. Conversely, turbidity levels were higher for chitosans with higher DD (higher charge density) than for chitosans with lower DD (lower charge density). PMC particles from chitosans with different molecular weights were characterized by scanning electron microscopy, laser Doppler electrophoresis, and dynamic light scattering. PMCs from high-molecular-weight chitosan were more spherical and those from medium-molecular-weight chitosan had a slightly larger hydrodynamic diameter than PMCs from the respective other two chitosans. The molecular weight of the chitosan was concluded to have no effect on the formation of chitosan-CNC PMC particles and only a minor effect on the shape and size of the particles. The higher turbidity levels for CNCs with lower sulfate group density and larger hydrodynamic diameter and for chitosans with higher DD were attributed to a larger number of CNCs being required for charge compensation.

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.

Mildly processed chitin used in one-component drinking straws and single use materials: Strength, biodegradability and recyclability

We introduce a facile approach toward fully biobased single-use materials based on chitin nanofibers (ChNFs). The chitin is sourced directly from ocean biomass residues (crab shells) and processed under the principles of green chemistry. The material takes advantage of the inherent chemical and structural features of the native chitin, which yield ChNF with a low degree of deacetylation (3.7%), high crystallinity (∼81%) and axial aspect (∼20 μm fibril length). Membranes of densely packed nano-networks are first developed, achieving excellent mechanical strength and self-adhesion, suitable for conversion into objects of tailorable geometries, including small diameter cylindrical drinking straws and conventional tabletop utensils. Van der Waals forces and hydrogen bonding contribute to strong interfiber interaction between chitin crystallites, leading to good interfacial adhesion and excellent mechanical performance. The obtained materials are demonstrated for their recyclability and biodegradability in natural environments, addressing the drawbacks of non-renewable products, considering circularity and end of life. Given the abundance of the sourced chitin, its intrinsic micro-structural design and self-adhesion, this work advances a sustainable alternative to single-use products based on nonrenewable carbon.

Impact of Chitosan on the Mechanical Stability of Soils.

Chitosan is becoming increasingly applied in agriculture, mostly as a powder, however little is known about its effect on soil mechanical properties. Uniaxial compression test was performed for cylindrical soil aggregates prepared from four soils of various properties (very acidic Podzol, acidic Arenosol, neutral Fluvisol and alkaline Umbrisol) containing different proportions of two kinds of chitosan (CS1 of higher molecular mass and lower deacetylation degree, and CS2 of lower molecular mass and higher deacetylation degree), pretreated with 1 and 10 wetting–drying cycles. In most cases increasing chitosan rates successively decreased the mechanical stability of soils that was accompanied by a tendential increase in soil porosity. In one case (Fluvisol treated with CS2) the porosity decreased and mechanical stability increased with increasing chitosan dose. The behavior of acidic soils (Podzol and Arenosol) treated with CS2, differed from the other soils: after an initial decrease, the strength of aggregates increased with increasing chitosan amendment, despite the porosity consequently decreasing. After 10 wetting–drying cycles, the strength of the aggregates of acidic soils appeared to increase while it decreased for neutral and alkaline soils. Possible mechanisms of soil–chitosan interactions affecting mechanical strength are discussed and linked with soil water stability and wettability.

Pickering emulsions stabilized with chitosan/gum Arabic particles: Effect of chitosan degree of deacetylation on the physicochemical properties and cannabidiol (CBD) topical delivery

Pickering emulsions (PEs) have recently gained increasing attention as green carriers of bioactive agents due to their surfactant-free and eco-friendly nature. Herein, the effect of the degree of deacetylation (DDA) of chitosan on the properties of chitosan/gum Arabic (CH/GA) particles and PEs was investigated. CH/GA particles with a DDA of 96% (high DDA) and 78% (low DDA) were prepared. The contact angle of water drop for the CH/GA particles prepared with high and low DDA chitosan was 84.2° and 77.5°, respectively. The dynamic interfacial tension of the particles has shown lower values with high DDA chitosan. The high DDA PE formulation exhibited higher stability after two months of storage than its counterpart prepared with low DDA chitosan. The mean emulsion droplet size was 15.6 ± 4.3 µm and 21.1 ± 2.6 µm for PEs prepared with high and low DDA chitosan, respectively. Both PE formulations demonstrated shear thinning and elastic gel-like properties. The amount of cannabidiol absorbed by the stratum corneum, viable epidermis and dermis was significantly higher in both PE formulations than the permeated amount, but no significant difference was observed between the amounts absorbed from both formulations.

Morphology-controlled synthesis of gold nanoparticles with chitosan for catalytic reduction of nitrophenol

Gold nanoparticles (AuNPs) were synthesized using chitosan as both reducing agent and stabilizer and characterized by UV–vis spectra and transmission electron microscope (TEM). Synthesized AuNPs were used in the reduction of nitrophenol to aminophenol in the presence of NaBH4. The experimental parameters such as the dosage of catalyst, NaBH4/4-nitrophenol molar ratio, temperature, AuNPs obtained under different synthetic conditions were investigated in detail. The reaction rate constants were calculated through the pseudo-first-order kinetic equation. The results indicated that the morphology of AuNPs was controllable just by adjusting the concentration, molecular weight (MW) and degree of deacetylation (DD) of chitosan. The catalytic activities of as-prepared AuNPs was dependent on their morphology and the nature of the reducing agent and stabilizer. Triangular AuNPs synthesized by 0.1% (w/v) chitosan with low DD (63.1%) showed the highest reaction rate constant 0.7050 min−1, which was followed by spherical and small AuNPs (around 10 nm) synthesized by 0.01% (w/v) chitosan and irregular and large AuNPs with wide size distribution synthesized by 0.3% (w/v) chitosan. The values of thermodynamic parameters including activation energy, enthalpy change, entropy change and Gibbs free energy change for the activation were calculated and revealed that the activation of catalytic process was non-spontaneous and endothermic. A comparative study for the catalytic reduction of three kinds of nitrophenols showed that the catalytic activity order of AuNPs was 3-nitrophenol > 2-nitrophenol > 4-nitrophenol.

Early Application of Quaternized Chitin Derivatives Inhibits Hypertrophic Scar Formation.

Various treatments for hypertrophic scars (HS) are applied after wound re-epithelialization. However, the lack of early intervention within the wound bed leads to poor HS treatment outcomes. In this study, quaternized chitin (QC) derivatives with different degrees of deacetylation (7.4% and 78.9%) are synthesized and their effects on HS formation are evaluated in a rabbit ear scar model. Early application of QC alleviates scar hypertrophy without delayed wound healing. Fibroblast count, collagen content, and α-smooth muscle actin expression are decreased, while matrix metalloproteinase-1 is upregulated on day 35 in the QC treatment group. QC suppresses inflammatory cell infiltration and IL-6 expression. A subsequent reduction in transforming growth factor β1 expression is also observed. The inhibitory effect of QC on HS formation is eliminated through the administration of exogenous IL-6. Taken together, early application of QC inhibits HS formation by downregulating IL-6 expression, and QC with a low degree of deacetylation tends to be more effective. Considering its potential for accelerating wound healing, inhibiting HS formation, and its antibacterial activity, QC may be used as an effective dressing in clinical woundmanagement.

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.

Comparison of the Physicochemical Properties of Chitin Extracted from Cicada orni Sloughs Harvested in Three Different Years and Characterization of the Resulting Chitosan

Chitin and its derivative chitosan are among the most used polysaccharides for biomedical and pharmaceutical applications. Most of the commercially available chitin is obtained from seafood wastes. However, the interest in alternative renewable sources of chitin and chitosan, such as insects, is growing. When new sources are identified, their stability over time has to be evaluated to allow for their commercialization. The aim of this study is to compare the physicochemical properties of chitin extracted from Cicada orni sloughs harvested in three different years (2017, 2019 and 2020) in order to assess the stability of the source and the repeatability of the extraction process. Chitin and its derivative chitosan were characterized by simple techniques such as Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Results suggest that the physicochemical properties of the extracted chitin varied from year to year, and that these differences are not due to the extraction process, but rather to intrinsic differences within the source. We showed that these differences could already be detected by analyzing the raw material (i.e., cicada sloughs) using the above-mentioned simple methods. The chitosan obtained from deacetylation of chitin had a low degree of deacetylation (66.2±1.6%). This low degree of deacetylation can be attributed to the deacetylation process, which is probably not appropriate for this source of chitin.

Effects of the Deacetylation Degree of Chitosan on 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) Formation in Chemical Models and Beef Patties

The effects of the deacetylation degree (DD) of chitosan on heterocyclic aromatic amine formation were investigated in chemical models and beef patties. The results in model systems showed that at lower addition levels (10 mg), chitosan with 85% DD showed the strongest inhibitory effect against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation, while chitosan with a higher DD (95%) or a lower DD (72 and 50%) did not show any significantly inhibitory effect. Further mechanism study showed that chitosan addition reduced the content of Maillard reaction intermediates including phenylacetaldehyde and the aldol condensation product but increased the PhIP precursor creatinine residue in the chemical model, indicating that chitosan at least partially competed with creatinine to react with phenylacetaldehyde to inhibit PhIP formation. In roast beef patties, 0.15% (w/w) chitosan (85% DD) significantly reduced the formation of PhIP, MeIQx, 4,8-DiMeIQx, Harman, and Norharman by 56.21, 33.32, 31.35, 25.14, and 28.12%, respectively. Moreover, chitosan significantly inhibited the formation of aldehydes in roast beef patties, further confirming the above-mentioned inhibition mechanism. However, the addition of chitosan might promote fatty acid oxidation. In addition, chitosan addition below 0.15% (w/w) had no significant effect on the textural properties of the roast samples.

Low deacetylation degree chitosan oligosaccharide protects against IL-1β induced inflammation and enhances autophagy activity in human chondrocytes

Osteoarthritis (OA) is a degenerative joint disease, which can lead to joint pain, stiffness, deformity and dysfunction, that seriously affects the quality of life in patients. At present, the treatments of OA mainly include early pharmacological treatment and late joint replacement. However, current pharmacological treatment has limited efficacy and undesired side effects. Chitosan oligosaccharide (COS) is a kind of nontoxic and biodegradable oligo-saccharide, which is composed of 2–20 glucosamine or N-acetylglucosamine linked by β-1,4 glycosidic bond. Studies have shown that COS has significant biological properties like antimicrobial, anti-inflammatory, antioxidant, and anti-tumor, as well as immunoregulation ability. However, the effects of COS on OA have not been clarified. In this study, we explored the protective effects of COS with different degrees of deacetylation on chondrocytes stimulated by interleukin 1β (IL-1β) in vitro. The results showed that IL-1β inhibited cell proliferation and promoted cell apoptosis. Besides that, IL-1β increased the expression of the major chondro-degrading genes MMP13 and ADAMTS-5, while decreased the expression of COL2A and ACAN. COS with different degrees of deacetylation (HDACOS, MDACOS, LDACOS) had different effects on IL-1β induced inflammation. LDACOS had the most obvious anti-inflammatory effects to inhibit the expression of MMP13 and ADAMTS-5 while promoted the expression of COL2A and ACAN. In addition, we found that the expression of autophagy-related gene Beclin-1 was up-regulated, and the ratio of LC3-II/LC3-I was increased in the LDACOS group. Furthermore, transmission electron microscopy (TEM) analysis showed that the number of intracellular autophagosomes increased significantly with the treatment of LDACOS. Based on our research, we suggested that LDACOS could inhibit chondrocytes inflammation and promote cell autophagy, and might be a protective drug for the treatment of OA.

Soft chemical processing approach for the valorization of seafood waste by-products as a source of bioactive polymers

Abstract Chitin and chitosan as green and active biomacromolecules were extracted from local seafood waste (shrimp shells). The extraction was carried out by a soft chemical process, followed by structural characterization (FTIR, XRD, viscosity average molecular weight M̅v), thermal stability by TGA, and antibacterial tests. FTIR and XRD spectra confirmed the chemical structures of the extracted chitin and chitosan which were similar to the commercial ones. The chitin and chitosan had an average viscosimetric molar weight of 232.21 kDa and 41 kDa, respectively. The chitosan had a high deacetylation degree (DD = 71 %) and low cristallinity index (Icr = 68.3 %); compared to chitin, which exhibited a lower deacetylation degree (DD = 24.27 %), higher thermal stability and higher cristallinity index (Icr = 87.55 %). A bacteriostatic effect of chitin was observed in the gram-negative bacteria, Escherichia coli, Salmonella typhimurium. Chitosan exhibited a bacteriostatic effect on all bacteria tested, except Salmonella typhimurium.

Influence of the Degree of Deacetylation of Chitosan and BMP-2 Concentration on Biocompatibility and Osteogenic Properties of BMP-2/PLA Granule-Loaded Chitosan/β-Glycerophosphate Hydrogels.

Compositions based on chitosan/β-glycerophosphate hydrogels with highly porous polylactide granules can be used to obtain moldable bone graft materials that have osteoinductive and osteoconductive properties. To eliminate the influence of such characteristics as chain length, degree of purification, and molecular weight on a designed material, the one-stock chitosan sample was reacetylated to degrees of deacetylation (DD%) of 19.5, 39, 49, 55, and 56. A study of the chitosan/β-glycerophosphate hydrogel with chitosan of a reduced DD% showed that a low degree of deacetylation increased the MSCs (multipotent stromal cells) viability rate in vitro and reduced the leukocyte infiltration in subcutaneous implantation to Wistar rats in vivo. The addition of 12 wt% polylactide granules resulted in optimal composite mechanical and moldable properties, and increased the modulus of elasticity of the hydrogel-based material by approximately 100 times. Excessive filling of the material with PLA (polylactide) granules (more than 20%) led to material destruction at a ~10% strain. Osteoinductive and osteoconductive properties of the chitosan hydrogel-based material with reacetylated chitosan (39 DD%) and highly porous polylactide granules impregnated with BMP-2 (bone morphogenetic protein-2) have been demonstrated in models of orthotopic and ectopic bone formation. When implanted into a critical-size calvarial defect in rats, the optimal concentration of BMP-2 was 10 μg/mL: bone tissue areas filled the entire material’s thickness. Implantation of the material with 50 μg/mL BMP-2 was accompanied with excessive growth of bone tissue and material displacement beyond the defect. Significant osteoinductive and osteoconductive properties of the material with 10 μg/mL of BMP-2 were also shown in subcutaneous implantation.

Characterization of Chitosan-Based Scaffolds Seeded with Sheep Nasal Chondrocytes for Cartilage Tissue Engineering.

The treatment of cartilage defect remains a challenging issue in clinical practice. Chitosan-based materials have been recognized as a suitable microenvironment for chondrocyte adhesion, proliferation and differentiation forming articular cartilage. The use of nasal chondrocytes to culture articular cartilage on an appropriate scaffold emerged as a promising novel strategy for cartilage regeneration. Beside excellent properties, chitosan lacks in biological activity, such as RGD-sequences. In this work, we have prepared pure and protein-modified chitosan scaffolds of different deacetylation degree and molecular weight as platforms for the culture of sheep nasal chondrocytes. Fibronectin (FN) was chosen as an adhesive protein for the improvement of chitosan bioactivity. Prepared scaffolds were characterised in terms of microstructure, physical and biodegradation properties, while FN interactions with different chitosans were investigated through adsorption-desorption studies. The results indicated faster enzymatic degradation of chitosan scaffolds with lower deacetylation degree, while better FN interactions with material were achieved on chitosan with higher number of amine groups. Histological and immunohistochemical analysis of in vitro engineered cartilage grafts showed presence of hyaline cartilage produced by nasal chondrocytes.

Chitosan of Peppery Milky Cap Fungi (Lactarius Pergamenus (Fr.) Fr): Isolation, Study of Physico-Chemical Properties and Biological Activity

Chitosan is widely used in biology and medicine. Usually, it is isolated from chitin of crustaceans, while chitosan of the basidiomycetes fungi is poorly studied. The purpose of this study was: 1) to develop a method for isolation of chitosan from dried pomace of the peppery milky cap (Lactarius pergamenus); 2) to study of physico-chemical and biological properties of the isolated chitosan. As tradicionally, chitosan was obtained by the alkaline hydrolysis of chitin. The determination of its molecular mass was performed using the viscometric method and further analyzed by disk electrophoresis (pH 5.0). The anti-microbial and cytotoxic activities were measured spectrophoto�metrically as a convertion of MTT dye to formazan, while the antifungal activity was evaluated using by counting colony-forming units (CFU). Chitosan of L. pergamenus fungi was shown to have lower molecular mass and a lower degree of deacetylation compared to shrimp chitosan. A yield of chitosan from a pomace of L. pergamenus was 6.27%. A heterogeneous product was obtained with an average molecular mass of 72 kDa and a degree of deacetylation equal - 87.1%. In 10 mg/ml dose, it inhibited by 29% the growth of gram-positive of Staphylococcus aureus (ATCC25923) bacteria and inhibited growth of gram-negative Echerichia coli dH5a - by 86% and Pseudomonas aeruginosa (ATCC9027) bacteria by 55%. Approximately 50 and 90 % of Candida albicans (pat.) cells were killed at the action of chitosan in doses of 0.025 mg/mL and 0.1 mg/mL correspondingly. It should be noted that this chitosan preparation did not affect a growth of human embryonic kidney pseudonormal cells of HEK 293 line and human breast carcinoma cells of MCF7 line.