Method for forming chitosan film coating and chitosan film coating

FIELD: medicine.

SUBSTANCE: chitosan is dissolved in an organic acid: 4-6% citric acid or 2-8% lactic acid in the relation of the ingredients chitosan: the organic acid 1:2-1:4 to prepare a forming solution. Chitosan has molecular weight 80-500 kDa. The forming solution is added with vitamin B1 in the amount of max. 0.5 wt %. The prepared forming solution is applied on a substrate in the amount of 0.2-0.25 ml/cm2 and kept to achieve a film structure. Said method is used to form the chitosan film coating having the thickness of 50-250 mcm and the breaking elongation of 42 to 470%.

EFFECT: group of inventions allows preparing high-elastic chitosan citrate or lactate films possessing bactericidal action.

2 cl, 1 tbl, 13 ex

 

Group of inventions relates to chemical and biochemical technologies, in particular to methods for thin elastomeric films and film materials based on chitosan with enhanced therapeutic capabilities, and can be used in medicine, pharmacology, biology, as well as in the cosmetic and food industry.

The aminopolysaccharide coated chitosan, derived from chitin shells of crustaceans, characterized by a number of valuable properties - non-toxic, has a high sorption capacity, exhibits antibacterial and antifungal activity, is biocompatible with human tissues, affects the regeneration of damaged skin, biodegration natural metabolic by and others

The combination of unique properties of chitosan with valuable qualities of organic acids multipurpose use (used, for example, in cosmetics, medicine, pharmacology, food industry and others) can be used when creating new chitosan-containing materials of different functional purpose.

Film materials based on chitosan traditionally formed by a dry method from aqueous acid solutions in which the polymer is in a salt form [Vikhoreva GA, galbraikh PS Film and fiber-based chitin and its derivatives // Chitin and chitosan: Receipt is, properties and application. M.: Nauka. 2002. S-279]. Most often to dissolve the chitosan used acetic acid concentration=2-10%. The use of acetic acid with<2% and>10% is not economically feasible, and with>10% more and environmentally unsafe. Thin films of chitosan acetate are characterized by sufficient (for the purposes of medicine, pharmacology, cosmetology and others) strength. However, a disadvantage of these films is their low elasticity. For example, freshly formed film of chitosan acetate (molecular weightkDa and a deacetylation 80-90%) of thickness d=50-250 microns, obtained from solutions of the polymer in acetic acid with C=2-10%, are characterized by the relative elongation at break ε=2.6-14.7% [Zotkin M.A., Vikhoreva GA, kechek'yan A.S. thermal modification of chitosan films in the form of salts with various acids // polymer sciense ser. Conn. 2004. V.46 B. No. 2. S-363; nud'ga L.A., Petrov V.A., Hoffman IV and other Chemical and structural transformations in chitosan films during storage, Zh. butt, chemistry. 2008. T. No. 11. S-1881; Fedoseyev, E.N., Alekseeva F, A.L. Smirnova // Bulletin of Nizhegorodsk. Univ. 2008. No. 5. P.58-62; Fedoseyev, E.N., Alekseeva F, Nistratov V.P., Smirnov, A.L.// Zavodskaya laboratoriya. Diagnostics of materials. 2009. T. No. 7. Pp.42-46].

Films of chitosan obtained from solutions in which the iMER in formic and propionic acid concentration=2%, also are characterized by relatively high strength and low elasticity, the value of ε=7-17% [Zotkin M.A., Vikhoreva GA, kechek'yan Astromomical of chitosan films in the form of salts with various acids // polymer sciense ser. Conn. 2004. V.46 B. No. 2. S-363]. Heat treatment of these films, and also obtained from chitosan solutions in acetic acid=2%, at 120°C for 3 hours strengthens film, and virtually no effect on the elasticity: the relative elongation at break teavararotonga films of acetate, propionate and formate, chitosan was ε=5-11%.

Known to produce films of chitosan solutions in the salt, oil, valerianic, benzoic acid and Caprylic acid [M. Alekseeva, Fedoseeva E., Frolov V., Nistratov V., Smirnova L. The strength of chitosan films. The role of molecular weight, the degree of order, the nature ofcontre-ion // Progress on chemistry and application of chitin and its derivatives. Media-Press. Lodz. Poland. 2009. V.XIV. P.65-74]. The resulting films have a relatively high resistance, the magnitude of the burst stress (σ) is extremely dependent on the length of the hydrocarbon radical of the acid used in the composition of the solvent. However, the elasticity of the films is low. For example, a film obtained from a solution of chitosan in hydrochloric acid, characterized by the relative elongation at break ε=1.2-2.5%. With increasing hydrocarbon radical of the acid used for dissolving chitosan, Macheda gradual degeneration of the plot forced elastic deformation to the deformation curve. Elasticity was observed only in films of chitosan obtained from solutions of the polymer in Caprylic acid: film freely curled into a tight roll and then without damage unfold. However, quantitative data on the relative elongation at break of such films are not shown.

Powder compositions of chitosan with succinic acid is used as agrochemical products [Gamzazade A.I. Derivative of chitin/chitosan controlled patterns as potential new biomaterials // Dis... D. chem. N. Moscow. 2005. 363 C.]. Swelling onkodispansere fraction of chitosan in a highly polar solvent in acid medium followed by the addition of succinic acid is used to produce water-soluble derivatives of chitosan [RF Patent №2099351]. Colloidal solutions of chitosan lactic acid are used to obtain dietary products [I.A. Evdokimov, Vasilishin SV, Aliyev LR and other physicochemical characteristics of chitosan solutions // journal of Newcaslte. Ser. Food. 2003. V.6. No. 1. http://www.nestu.ru]. Multicomponent composition of complex composition, including additional small amounts of chitosan (0.5-1.0 wt.%) and citric acid (0.05-0.5 wt.%), are used to obtain hair balm anti-inflammatory effect, prevents hair loss and is the education of dandruff [the Application for the invention of the Russian Federation No. 93032461/14, 21.06.1993], preparations for the treatment of hand [the Application for the invention of the Russian Federation No. 2006117617/15, 23.05.2006]. The problem of obtaining highly elastic films and film materials from such compositions and colloidal solutions were not set.

Know the use of chitosan and 1%citric acid solution to obtain a functional food product containing chitosan, fat phospholipid product, flavor additives, powder of husks pumpkin powder, grape seed and powder from malt legumes [the Application for the invention of the Russian Federation No. 2007110612/13, 22.03.2007]. Phospholipid product is produced by four-time mixing the pre-heated vegetable phospholipids with an organic solvent, and before the third mixing add 1%solution of citric acid in flooded acetone. Obtaining a highly elastic films and film materials of chitosan in the task was not raised.

Known modified chitosan product and method of its production, including the stage of preparing an acidic aqueous solution of chitosan, remove nerastvorim particles by filtration and/or sedimentation and cross-linking of the chitosan in the presence of an organic solvent and a surfactant in acid, neutral or weakly alkaline or alkaline conditions, depending on the crosslinking agent, when continuous is m dispersion, stipulating before joining chitosan template synthesis or hematoglobinopathias [the Application for the invention of the Russian Federation No. 2005125946/04, 04.08.2005]. As a cross-linking agent used saturated or unsaturated carboxylic, dicarboxylic or tricarboxylic acids such as acetoxystyrene, glycoxylate, glutaric, diatsetilvinny, digitalia, Takanawa, cinnamic, crotonic, citric, maleic, malonic, methacrylic, medianama, propionic, Papanova, salicylic, phthalic, fumaric, Tarakanova, oxalic, succinic, or their anhydrides, or their galodamadruga, or dihalogenide, or aldehydes or their dialdehyde, or hydroxy - or oxoproline, or diglyceride esters, or other derivatives. Modified chitosan product can be obtained in the form of fractal chitosan particles with a characteristic size of nanofraction not less than 1 nm and not more than 5000 nm or cross stitched mesh polymer with many spherical cavities having a size of not less than 1 nm and not more than 5000 nm.

Modified chitosan product can be used to obtain water-soluble chitosan gel with the structure of chitosan mass in the form of fractal chitosan particles or cross stitched mesh polymer with many spherical cavities by dispergirovany the Oia modified chitosan product in water followed by the addition of acid, permitted for use in cosmetics, Pharmacopoeia or the food industry, a thorough mixing of the composition and curing for at least 1 minute as the use acetic acid or citric or formic, or benzoic acid, or salicylic acid, or aspirin, or glycol, or nicotine, or deoxybenzoin, or milk, or oxalic acid, or any mixture.

The disadvantage of this method is the multi-stage receiving the finished product, its complex structure and high cost. The task of obtaining modified chitosan product in the form of a highly elastic films and film materials not applicable.

Closest to the claimed film-coated chitosan is a bandage for the treatment of wounds in the form of a film containing chitosan derived from crab shells, polyvinyl alcohol, glutaric aldehyde and biologically active additives [RF Patent №2219954]. This film contains chitosan in the form of a salt of an organic acid selected from acetic, succinic, or glycolic acid.

The lack of bandages to treat wounds in the form of a film is a small content of chitosan (1-6 wt.%). The main content of the bandage is polyvinyl alcohol (60-90 wt.%), which, unlike chitosan, is not biologically active polymer which does not show antibacterial, reparative and other properties. In addition, the bandage contains a toxic substance - glutaric aldehyde, which is the cross-linking agent. Due to the formation of uncontrolled crosslinking between glutaraldehyde, chitosan and polyvinyl alcohol such multicomponent film has low elasticity.

The closest solution to the proposed method of obtaining a film coatings based on chitosan is a method for wound dressings comprising dissolving chitosan and collagenopathies protein in the organic acid, dialysis of the resulting solution, the introduction of auxiliary substances and amendment and freeze drying, the organic acid is used polynovo carboxylic acid, or a mixture polienovykh carboxylic acids in the ratio specified acid: soluble substances from 1:4 to 2:1 on a dry weight basis, and after dialysis in the mixture impose additional low molecular weight amino acid [RF Patent №2240830]. The method involves the introduction of a plasticizer (chosen from groups of the polyalcohol such as glycerin and/or polyvinyl alcohol) and excipients that enhance antibacterial protection (e.g., chlorhexidine, biolucent, polisept).

The disadvantage of this method of obtaining wound cover is a multi-stage and length of alnost process, the need to comply with certain temperature when preparing solutions of components, mandatory retention stage of the dialysis solution at a ratio of dializuetsa solution to water of not less than 1:100 for at least 16 hours, the introduction of aggressive cross-linking agent is glutaraldehyde, the introduction of a plasticizer and a special biologically active substances, as well as freezing in freeze-drying chamber and freeze drying. This leads to a high cost of wound dressings. In addition, the resulting wound covering, despite the high wound-healing properties, are unable to simulate the surface of the wound, especially surfaces with difficult terrain. This, in turn, reduces therapeutic effect of this wound dressings.

The technical result of the claimed group of inventions is to improve the elasticity of the films based on chitosan while simplifying the technology of its manufacture, as well as enhancing its biocidal properties.

The task was solved by creating a flexible film coatings based on chitosan comprising chitosan in the form of salts of organic acids, according to the technical solution of the relative elongation at break of the film coating is not less than 40%, as well as organic acids using an aqueous solution of 4-6%lim is authorized or 2-8%lactic acid, when the ratio of components, wt.%:

chitosan - 40-80,

organic acid - 2-8,

water - the rest.

To improve the processes of carbohydrate, protein and fat metabolism film coating can include vitamin B1 in an amount of not more than 0.5 wt.%.

Also the problem is solved in that in the method of obtaining a film coatings based on chitosan, which includes dissolving chitosan in organic acid with molding solution, applying the obtained molding solution on the substrate, followed by curing solution on the substrate before reaching the film structure as the organic acid is used 4-6%citric acid or 2-8%lactic acid, in a ratio of components chitosan: an organic acid of 1:2-1:4, wt.%. Additionally, in forming solution is injected vitamin B1 in an amount of not more than 0.5 wt.%. When the preparation of the molding solution using chitosan with molecular weight of 80-500 kDa. To obtain a film thickness of 50-250 μm forming solution onto the substrate in the amount of 0.2-0.25 ml/cm2of the substrate.

The inventive method is as follows. A portion of the chitosan is dissolved in an aqueous solution of citric or lactic acid fixed concentration. Thus forming solution, which is transferred onto an inert substrate and evaporated the solvent within 3-7 days depending on the nature and concentration of the acid (range 2-8%) at room temperature (T≅22±2°C) under static conditions. Then the film sample is separated from the substrate, define its thickness, which can range 50-250 μm, elastic-plastic characterization and bactericidal properties.

Used samples of chitosan with a molecular masskDa and with a close degree of dezazetilirovanie 80-85 mol.%.

The thickness of the film (d) of chitosan was measured by a micrometer with a multiplier is 10 μm. The measurements were carried out several times in different parts of the film were then calculated the average thickness value.

Elastic-plastic properties of the films was determined according to GOST №14236-81 [polymer Films. Method of tensile test] on a tensile testing machine uniaxial tension Tira Test 28005 with a cell load of 100 N. Breaking load and elongation were determined at break. Breaking stress (σ) was determined taking into account the cross-sectional area of the sample taken for testing, and expressed in MPa. Elongation at break (ε) was calculated based on the original length of the film sample taken for the test, and expressed as a percentage.

Bactericidal properties of films were studied on the example of gram-negative and gram-positive microorganisms wound infections: the test strains cultures of Escherichia coli Esherichia coli and Staphylococcus aureus Staphylococus aureus. The microorganisms were sown "lawn seeding" on solid nutrient medium AG is. A film of chitosan with a diameter of 4 mm was placed on seeded with a lawn of bacterial culture. The exposure time was 24 hours. Bactericidal activity was controlled by the magnitude of the diameter of zone of inhibition (D, mm) seeded lawn cultures of microorganisms in place of the test thin film sample. The results obtained by averaging 4-6 parallel experience.

The applicability of the proposed solutions is illustrated by the following examples.

The group of examples 1-10. Obtaining chitosan films from solutions of the polymer in citric or lactic acid, physico-mechanical properties of films from citrate and lactate chitosan.

Example 1. A portion of 2 g of chitosan withkDa dissolved in 100 ml of 4%aqueous citric acid solution. This forming solution in a volume of 20 ml is transferred to a polyethylene substrate and the solvent is evaporated in a period of 3-4 days at room temperature under static conditions. The ratio of the components in the finished film coating was, wt.%: chitosan - 80, an organic acid - 4, water - the rest. The thickness of the film of chitosan citrate amounted to d=50 ám.

Formed film sample is subjected to uniaxial stretching on a tensile testing machine. Relative elongation at break was ε=48% when the discontinuous stress σ=9.7 MPa.

Example 2 is an is logical to example 1. The difference was in the use of the design of chitosan withkDa. The ratio of components in the film was, wt.%: chitosan - 78, organic acid - 4, water - the rest. The thickness of the film of chitosan citrate amounted to d=100 μm, the relative elongation at break ε=60%, breaking stress σ=0.4 MPa.

Example 3 is identical to example 1. The difference was in the use of the design of chitosan withkDa and 6%aqueous citric acid solution.

The ratio of components in the film, wt.%: chitosan - 75, organic acid - 6, water - the rest. Specifications: thick film of chitosan citrate d=60 μm, the relative elongation at break ε=70%, breaking stress σ=0.2 MPa.

Example 4 is similar to example 1. The difference was the additional introduction in forming solution of vitamin B1 in the amount of not more than 0.5 wt.% by weight of the molding solution (example 1). The ratio of components, wt.%: chitosan - 80, an organic acid, 4 - vitamin B1-0.5, water - the rest. Specifications: thick film of chitosan citrate d=50 μm, the relative elongation at break ε=42%, breaking stress σ=3.0 MPa.

Example 5 is similar to example 1. The difference was in the use of a 2%aqueous solution of lactic acid. The ratio of components in the PLU is Kyo was, wt.%: chitosan - 80, an organic acid - 2, water - the rest. The film thickness of the chitosan lactate was d=95±5 μm, the relative elongation at break ε=47.5%, breaking stress σ=9.1 MPa.

Example 6 is identical to that of example 5. The difference was in the use of the design of chitosan withkDa. The ratio of components in the film, wt.%: chitosan - 80, an organic acid - 2, water - the rest. The film thickness of the chitosan lactate was d=95±5 μm, the relative elongation at break ε=50%, breaking stress σ=14.5 MPa.

Example 7 is identical to that of example 5. The difference was in the use of a 4%aqueous solution of lactic acid. The ratio of components in the film, wt.%: chitosan - 50, an organic acid - 4, water - the rest. The film thickness of the chitosan lactate was d=190±10 μm, the relative elongation at break ε=180%, breaking stress σ=3.6 MPa.

Example 8 is similar to example 7. The difference was in the use of the design of chitosan withkDa. The ratio of components in the film, wt.%: chitosan - 40, an organic acid - 4, water - the rest. The film thickness of the chitosan lactate was d=210±10 μm, the relative elongation at break ε=200%, breaking stress σ=0.8 MPa.

Example 9 is similar to example 7. Great for the e was to use a sample of chitosan with kDa. The ratio of components in the film, wt.%: chitosan - 40, an organic acid - 4, water - the rest. The film thickness of the chitosan lactate was d=235±15 μm, the relative elongation at break ε=470%, breaking stress σ=0.8 MPa.

Example 10 is identical to that of example 8. The difference was in the use of an 8%aqueous solution of lactic acid. The ratio of components in the film, wt.%: chitosan - 40, an organic acid - 8, water - the rest. The film thickness of the chitosan lactate was d=220±20 μm, the relative elongation at break ε=300%, breaking stress σ=0.8 MPa.

When placed in a film coating obtained in examples 1-10, on a surface with complex terrain (e.g., on the convex areas of the frontal or dorsal sides of the body, the distal part of the upper limb, plantar or dorsal surfaces of the foot and so on) is the modeling of the surface profile due to the elastic properties of the film.

Examples 11, 12 (alternative examples of complete film coating). Obtaining chitosan films from solutions of the polymer in acetic or succinic acid, physico-mechanical characteristics of the films of acetate and succinate chitosan.

Example 11 is identical to that of example 1. The difference was in the use of a 2%aqueous solution of acetic acid. The ratio of the components of the clients in the film, wt.%: chitosan - 80, an organic acid - 2, water - the rest. The film thickness of the chitosan acetate was d=55±5 μm, the relative elongation at break ε=1.4%, breaking stress σ=53.4 MPa.

Example 12 is similar to example 1. The difference was in the use of a 1.5%aqueous solution of succinic acid. The ratio of components in the film, wt.%: chitosan - 80, an organic acid - 1,5, water - the rest. The film thickness of the chitosan succinate was d=65±5 μm, the relative elongation at break ε=3.7%, breaking stress σ=37.6 MPa.

From the analysis of examples 1-12 follows that of the film of chitosan obtained from solutions of the polymer in citric or lactic acid, are characterized by a high elasticity. The value of the relative elongation at break of films from citrate and lactate, chitosan 20-50 and 120-335 times, respectively, higher in comparison with the films of succinate and acetate chitosan, i.e., obtained from solutions of the polymer in amber or acetic acid.

From the analysis of examples 1-10 derive the following optimal parameters for elastic film coatings based on chitosan comprising chitosan in the form of salts of organic acids, which use aqueous citric or lactic acid:

the concentration of citric acid=4-6 wt.% (regardless of what polymer), using With<4 wt.% impedes the dissolution of the polymer in a solution of citric acid=2 wt.% chitosan is not soluble, the use of>6 wt.% to obtain films uneconomical, because it increases the cost of the finished product;

the concentration of lactic acid=2-8 wt.% (regardlesspolymer), using With<2 wt.% impedes the dissolution of the polymer, the use of>8 wt.% increases the cost of the finished product.

Example 13. Bactericidal properties of films from citrate, lactate, acetate and succinate chitosan (table).

Table
Antibacterial properties of chitosan films in salt form
Concentration is
tion of chitosan solution WithHTZ, wt.%
The molecular mass of chitosan, kDaName acidThe concentration of the acid solution,%The diameter of zone of inhibition of growth of cultures of microorganisms D, mm
E.coliSt.aureus
87Milk29.2±0.511.3±0.5
411.0±0.312.6±1.0
Acetic29.0±0.48.0±2.0
Amber1.57.8±0.610.8±0.3
200Lemon47.4±0.27.2±0.8
Milk29.2±0.612.5±1.2
411.1±1.1>20
Acetic25.9±1.28.8±0.2

The table shows that the film of citrate and lactate, chitosan (the present invention), as well as acetate and succinate chitosan (comparative analysis) exhibit biocidal properties in the growth of cultures of microorganisms Esherichia coli and Staphylococus aureus. Most bacteria is rizicnim action have film of lactate and citrate, chitosan, regardless of the molecular weight of the polymer.

The proposed method allows to obtain a highly elastic film of citrate and lactate chitosan with sufficient strength for use in medical practice, pharmacology, cosmetology, food industry and others, simple, environmentally friendly and economically viable. As a result of application of the proposed method are non-toxic, highly elastic film coatings based on chitosan that can easily simulate the surface with a complex topography, with bactericidal action.

1. A method of obtaining a film coatings based on chitosan, bactericidal, comprising dissolving chitosan in organic acid with molding solution, applying the obtained molding solution on the substrate, followed by curing solution on the substrate before reaching the film structure, wherein the organic acid is used an aqueous solution of 4%to 6% citric or 2-8%lactic acid in a ratio of components chitosan: an organic acid of 1:2-1:4.

2. The method according to claim 1, characterized in that it further into forming solution is injected vitamin B1 in an amount of not more than 0.5 wt.%.

3. The method according to claim 1, characterized in that during the preparation of the molding solution using chitosan with molecular weight of 80-500 kDa

4. The method according to claim 1, characterized in that to obtain a film thickness of 50-250 μm forming solution onto the substrate in a volume of 0.2-0.25 ml/cm2of the substrate.

5. Film coating based on chitosan, bactericidal, obtained by the method according to claim 1, characterized in that the relative elongation at break of the film coating is from 42 to 470%.

6. Film coating based on chitosan, bactericidal, according to claim 5, characterized in that it additionally contains vitamin B1 in an amount of not more than 0.5 wt.%.



 

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SUBSTANCE: invention relates to a polyethylene film for making packaging, grocery sacks, trash can liners and produce bags. The film is made from a multimodal polymer composition obtained using a double metallocene catalyst and contains an ethylene homopolymer or a copolymer of ethylene and alpha-olefin comonomer or combination thereof and, optionally, additives and modifiers. The film is characterised by total energy dart drop, measured in accordance with ASTM D4272, greater than about 0.45 ft.lbf, dart drop impact strength, measured in accordance with ASTM D1709 Method A, greater than about 135 g, and moisture vapour transmission rate, measured in accordance with ASTM F1249 at 100°F and 90% relative humidity, less than about 0.85 g-mil/100 square inch/24 hour. Said tests are performed on a test specimen having a 0.8 mil thickness.

EFFECT: improved film properties.

20 cl, 2 dwg, 4 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: method involves preparation of material for enzymatic hydrolysis. Alkaline hydrolysis is carried out with proteolytic enzyme preparations with neutralisation of the obtained solution to pH=7. A salt is added to the obtained enzymatic hydrolysate to a value of not less than 0.1 mol/l. Successive ultrafiltration is carried out, first on a membrane with maximum retention of 50 kD with separation of high-molecular weight impurities, and then on a membrane with maximum retention of 5 kD with separation of low-molecular weight substances. The chondroitin sulphate solution retained at the membrane is washed on the same membrane with distilled water until complete removal of salts. Final washing with distilled water is carried out on a membrane with maxim retention of 50 kD.

EFFECT: invention enables to obtain a chondroitin sulphate preparation with weight ratio of the basic substance.

7 ex

FIELD: chemistry.

SUBSTANCE: method involves activation of hyaluronic acid using a cross-linking agent and an auxiliary cross-linking agent. The activated hyaluronic acid then reacts with a nucleophilic cross-linking agent. The pH of the reaction medium ranges from 8 to 12. The nucleophilic cross-linking agent contains at least 50 wt % oligopeptide or polypeptide. Further, pH of the reaction medium is regulated to 5-7 and cross-linked hyaluronic acid is precipitated in the organic solvent. The invention also relates to use of the cross-linked hyaluronic acid obtained using this method in plastic surgery to make implants and to a hedrogel containing said cross-linked hyaluronic acid in a buffer aqueous solvent.

EFFECT: invention enables to obtain cross-linked hyaluronic acid in dry form, having high resistance to decomposition factors such as temperature, free radicals and enzymes.

18 cl, 3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: disclosed is a method of determining antibacterial properties of chitosan by estimating its minimum bacteriostatic and/or bactericidal concentration. Complex buffer solutions based on three organic acids MES, ACES and TES with different pH values are prepared. The ready buffer solutions are poured into a vessel. Double dilutions of chitosan are then prepared in vessels with the buffer solutions. Aliquots of a bacterial suspension in a fluid medium are added to the chitosan solutions in the buffer. The solutions are incubated for 24 hours at temperature which is optimum for bacterial growth. The minimum bacteriostatic and/or minimum bactericidal concentration of chitosan is then determined after incubation by determining growth of the culture or a drop in the number of living cells, respectively.

EFFECT: invention enables to determine antibacterial properties of chitosan in a wide pH range from 5,50 to 8,00 without the need to use buffers of different chemical composition.

5 dwg, 2 ex

FIELD: medicine, pharmaceutics.

SUBSTANCE: invention refers to a method for preparing sodium salt of hyaluronic acid modified by boron compounds with no fluid medium added. The method consists in the fact that powdered sodium salt of hyaluronic acid together with a modifying agent and mixed modifying agents is pre-homogenised in a mixer at temperature ranging within 20° to 50°C; thereafter the prepared homogenous powder mixture is simultaneously exposed to pressure and shearing deformation in a mechanochemical reactor at temperature ranging within 20° to 50°C and pressure 5-1000 MPa.

EFFECT: invention provides preparing boron-containing sodium salt of hyaluronic acid applied in boron neutron capture therapy in one-stage process parameters with no fluid medium added which requires low power, labour and water consumptions.

13 cl, 15 ex

FIELD: medicine, pharmaceutics.

SUBSTANCE: invention refers to medicine, more specifically to producing chitosan oligomers possessing biological activity and applicable in food industry and medicine. In a method for producing chitosan oligomers, a chitosan solution is taken in the concentration of 0.025-0.075% (weight/volume) and exposed to low-frequency ultrasound of the intensity of 92-460 Wt/cm2 for 5-30 minutes.

EFFECT: reduction in price of the chitosan oligomers production combined with promotion of higher medium viscosity molecular weight of the product within the range 25 ÷ 120 kDa.

3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: method involves preliminary acetylation of chitin with acetic anhydride, washing and drying the acetylated chitin in order to reduce degree of deacetylation thereof and, as a result, increase output of the desired product - D(+)-glucosamine hydrochloride when obtaining said product through hydrolysis of acetylated chitin with concentrated hydrochloric acid while heating, followed by evaporation, crystallisation, separation, washing and drying the desired product.

EFFECT: high output of the desired product while maintaining its high quality; method is more environmentally friendly since pre-treatment of chitin reduces the amount of processing wastes.

1 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: method of producing chitosan chromate involves reaction of soluble chitosan salts with metal chromates in ratio of 2 moles of the chitosan cation to 1 mole of chromate anion or with metal bichromates in ratio of 4 moles of the chitosan cation to 1 mole of the bichromate anion. The solid chitosan chromate residue formed is then separated and dried at temperature not higher than 150°C. The invention discloses an energy-intensive composition based on chitosan dodecahydro-closo-dodecaborate containing an effective amount of chitosan chromate. The quantitative ratio in the energy-intensive composition is by the required combustion mode: the higher the content of chitosan chromate, the higher the activity of the composition.

EFFECT: invention enables to obtain a chemical compound having sufficiently high oxidative properties and suitable for use in energy-intensive compositions which burn without emitting harmful gaseous products.

3 cl, 5 ex

FIELD: chemistry.

SUBSTANCE: method involves taking a certain weighed amount of chitosanium chromate which is first purified from extraneous impurities and reduced to constant weight. The weighed amount is then turned into a stable weighted form through thermal treatment on air at temperature 800-900°C to form chromium oxide Cr2O3. The weight of the formed chromium oxide is then determined. Content of chromic acid in the initial weighed amount of chitosanium chromate is then calculated from the weight of chromium oxide. The degree of deacetylation of chitosan is calculated using defined formulae.

EFFECT: invention enables to increase accuracy of determining degree of deacetylation of chitosan.

2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of extracting and stabilising ultra low-molecular aminoglycans from eggshell wastes. Aminoglycan extract is used to produce cosmetic creams with skin moisturising and anti-wrinkle properties. The method of extracting low-molecular aminoglycan compound of formula I from a natural source of eggshell wastes, which consists of alternating glucuronic acid and N-acetylglucosamine units, where M can be one or more of Na, Ca, K, Mg; and n is a whole number from 20 to 40, involves the following steps: (a) preparing eggshell wastes for extraction of embryonic low-molecular aminoglycan compound of formula I using a polar organic solvent in water, (b) extracting low-molecular aminoglycan compound of formula I in form of a water-soluble salt, for which the eggshell from step (a) is vigorously shaken with aqueous polar salt solution at 10°C - 35°C for 6-12 hours, then filtered or centrifuged in order to collect an aqueous layer containing a dissolved aminoglycan compound of formula I; (c) extracting a purified low-molecular aminoglycan compound of formula I by forming a gel from an aqueous mixture of salts using a polar organic solvent, for which the solution from step (b) is successively and step-by-step mixed with an organic solvent mixed with water while gently stirring and then cooled to maintain temperature from 20°C to 25°C, and the formed gel is left for 2-24 hours for complete precipitation, then filtered or centrifuged in order to extract a semidry aminoglycan compound of formula I; (d) the extracted aminoglycan compound of formula I from step (c) is stabilised via gradual addition of organic oils to the semidry gel to form aminoglycan compound of formula I. In order to prepare a composition having anti-wrinkle properties, at least one pharmaceutically acceptable filler is added to the stabilised aminoglycan compound of formula I obtained at step (d).

EFFECT: method enables to obtain an aminoglycan compound of formula I with the necessary viscosity and skin penetrating properties for reducing skin wrinkles, as well as excellent softening and moisturising effects.

8 cl, 9 ex

FIELD: chemistry.

SUBSTANCE: method involves feeding wastes to be treated into artificial containers, biotreatement, tapping the filtrate and removing the obtained biomass. Biotreatement is carried out by culturing hoverfly larvae from the freshly laid eggs phase to the pupation phase in the fermented wastes to be treated, placed in artificial meshed containers the bottom and walls of which are covered with filter cloth. The apparatus has artificial containers, devices for feeding the wastes to be treated, outputting the filtrate and collecting the biomass. The artificial containers have a meshed bottom and walls covered with filter cloth.

EFFECT: invention enables to combine biotreatment of methane wastes with production of chitin containing biomass.

8 cl, 1 dwg

FIELD: fish industry.

SUBSTANCE: method involves providing deacetylation of raw material with the use of preliminarily cooled alkaline solution; washing and drying. Deacetylation process is performed in three stages, first stage being performed for 7 days and subsequent two stages being performed for 2 hours each, combined with thermal processing at temperature of 55-590C. Washing process is provided after each deacetylation stage.

EFFECT: provision for producing of chitosan from chitin of cancerous with increased extent of deacetylation, while native properties of natural polymer being kept, without breaking of glycoside binding chain.

3 ex

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