CA2134635A1 - Process for preparing aqueous chitosan solutions and gels - Google Patents
Process for preparing aqueous chitosan solutions and gelsInfo
- Publication number
- CA2134635A1 CA2134635A1 CA002134635A CA2134635A CA2134635A1 CA 2134635 A1 CA2134635 A1 CA 2134635A1 CA 002134635 A CA002134635 A CA 002134635A CA 2134635 A CA2134635 A CA 2134635A CA 2134635 A1 CA2134635 A1 CA 2134635A1
- Authority
- CA
- Canada
- Prior art keywords
- chitosan
- acid
- water
- chelating agent
- gels
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
- C08J3/075—Macromolecular gels
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
- C08B37/0027—2-Acetamido-2-deoxy-beta-glucans; Derivatives thereof
- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
- C08J2305/08—Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Dispersion Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Molecular Biology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Materials Engineering (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
- Cosmetics (AREA)
- Colloid Chemistry (AREA)
- Medicinal Preparation (AREA)
- Jellies, Jams, And Syrups (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Abstract The invention relates to a process for preparing aqueous solutions and gels of chitosan, in which chitosan and an acid chelating agent are dissolved in water.
Such solutions can have their viscosity drastically increased or be converted into high-viscosity gels, by adding salts of polyvalent metals and acids in which chitosan is only moderately soluble or insoluble.
From such solutions, salt-like chitosan-chelating agent adducts can be obtained by removal of water or by precipitation using an organic solvent.
Such solutions can have their viscosity drastically increased or be converted into high-viscosity gels, by adding salts of polyvalent metals and acids in which chitosan is only moderately soluble or insoluble.
From such solutions, salt-like chitosan-chelating agent adducts can be obtained by removal of water or by precipitation using an organic solvent.
Description
3~63~
,.. .
Process for ~reparing_aqueous chitosan solutions and The invention relates to a novel process for preparing aqueous solutions and gels of chitosan.
Chitosan is a cationic biopolymer which is built up of recurring units of 1,4-linked D-glucosamine.
Chitosan is the deacetylation product of chitin which is widely distributed in natural fauna as the skeletal substance of he armour and shells of crustaceans, insects and the like. ~ a natural raw material, which can be obtained in a simple and enviroNmentally compatible manner fro~ natural regenerable sources, chitosan is increasingly of interest in industrial applications. An essential property of chitosan is the ability to form viscous aqueous solutions. Such solutions can have a wide variety of applications in chemistry, pharmacy, cosmetics and food technology. Examples of these are, for instance, the use as thickener, gel former, binder, film for~er and adhesive. Chitosan al50 serveæ as a naturally degradable flocculant for waste-water purification. In the same application, the ability to bind heavy metals is aIso useful. As a biocompatible or bioresorbable polymer, chitosan is of particular interest in pharma~eutical and medical applications such as, for example, as a constituent of wound dressings or of materials for endoprostheses.
~ owever, the specific solubility characteristics of chitosan place limits on its practlcal use. The only suitable aqueous solvents for chitosan are monobasic mineral acids such as hydrochloric acid or aqueous solutionsiof some organic acids such as, for example, acetic acid and lactic acid. Chitosan is insoluble in polybasic inorganic acids such as sulfuric acid and phosphoric acid, and also in virtually all customary organic solvents. Chitosan solutions can therefore only be used where the aqueous-acid solvent is unpro~lemati-cal. The setting of certain viscosity values is essen-tially only possible via the concentration of chitosan in the solution. High-viscosity solutions or gels can only ,.
, .
,.. .
Process for ~reparing_aqueous chitosan solutions and The invention relates to a novel process for preparing aqueous solutions and gels of chitosan.
Chitosan is a cationic biopolymer which is built up of recurring units of 1,4-linked D-glucosamine.
Chitosan is the deacetylation product of chitin which is widely distributed in natural fauna as the skeletal substance of he armour and shells of crustaceans, insects and the like. ~ a natural raw material, which can be obtained in a simple and enviroNmentally compatible manner fro~ natural regenerable sources, chitosan is increasingly of interest in industrial applications. An essential property of chitosan is the ability to form viscous aqueous solutions. Such solutions can have a wide variety of applications in chemistry, pharmacy, cosmetics and food technology. Examples of these are, for instance, the use as thickener, gel former, binder, film for~er and adhesive. Chitosan al50 serveæ as a naturally degradable flocculant for waste-water purification. In the same application, the ability to bind heavy metals is aIso useful. As a biocompatible or bioresorbable polymer, chitosan is of particular interest in pharma~eutical and medical applications such as, for example, as a constituent of wound dressings or of materials for endoprostheses.
~ owever, the specific solubility characteristics of chitosan place limits on its practlcal use. The only suitable aqueous solvents for chitosan are monobasic mineral acids such as hydrochloric acid or aqueous solutionsiof some organic acids such as, for example, acetic acid and lactic acid. Chitosan is insoluble in polybasic inorganic acids such as sulfuric acid and phosphoric acid, and also in virtually all customary organic solvents. Chitosan solutions can therefore only be used where the aqueous-acid solvent is unpro~lemati-cal. The setting of certain viscosity values is essen-tially only possible via the concentration of chitosan in the solution. High-viscosity solutions or gels can only ,.
, .
2 ~ 3 ~ ~ 3 be achieved by means of a correspondingly high choice of the chitosan concentration, which in turn is undesired or disadvantageous for many applications. It would be desirable to have high viscosity values at a comparatively low chitosan concentration.
It has now been found that chitosan can be dissolved in water without problems in a wide concentration range if acid chelating agents are added.
Furthermore, it has been found that in such solutions the 10 visc08ity can be drastically increased up to high-viscosity gels without having to change the original chitosan concentration, if salts of polyvalent metals and acids in which chitosan is only moderately soluble or in~oluble are added to these solutions.
Finally, it has also been found that chitosan and chelating agents can be recovered in the form of a sàlt~
like adduct from a co~mon aqueous solution by removal of the water or by precipitation using an organic solvent.
This adduct can be redissolved in water without problems.
The invention accordingly provides a process for preparing aqueous solutions and gels of chitosan in which chitosan and an acid chelating agent are dissolved in water.
The invention further provides a process for preparing high-viscosity chitosan gels in which salts of polyvalent metals and acids in which chitosan is only moderately soluble or insoluble are added to aqueous solutions containing chitosan and an acid chelating agent.
The invention finally provides a salt-like adduct of ~hitosan and chelating agent which can be obtained from corresponding solutions by removal of water or by precipitation using an organic solvent.
In the process of the invention, any commercial chitosan can be used.
The acid chelating agents to be used in the process of ths invention are known per se, for instance ~rom the field of anal~tical chemistry and, in particular, from complexometric analysis. Chelating r~ 213 l 6 3 ~
agents which are suitable for the purpose of the invention are all bidentate or polydentate chelating agents which are able to form stable chelate complexes with, in particular, polyvalent metal ions. Preference is 5 given to using the readily commercially available com-plexing agents nitrilotriacetic acid (NTA), ethylene-diaminetetraacetic acid tEDTA), diethylenetriaminepenta-acetic acid (DTPA), triethylenetetraminehexaacetic acid (~T~A) or diam~nocyclohexanetetraacetic acid (DCTA).
~hese can, preferably, ~e used in the form of the free acids, but also in the form of their (partial) sodium salts. Partiaular preference is given to EDTA.
It has been found that chitosan together with such chelating agents ~an be dissolved without p~oblems in water in a wide concentration range, with the mass ratio of chitosan to the complexing agent also being largely unproblematical. ~hus, chitosan and chelating agents in a mass ratio of from 1:0.3 to 1:5 can be readily dissolved in water to give solutions having a total content of from O.l`to 2~% by weight. In the case of low-molecular-weight chitosan, even higher total contents, for instance up to about 50% by weight, are possible. These findings are very surprising, since, on the one hand, the chelating agents have only a weak acid character in comparison with the acids or acid solutions customary as solvents for chitosan and, on the other hand, these chelating agents have only a low solubility in water itself. Thus, for example, onl~ 0.5 g~l of EDTA
dissolve in water at 22.5~C; for NTA this figure is 1.28 g~l and for DTPA the figure is 3.5 g/l. It is assumed that chitosan and chelating agents have a mutually reinforcing solubility-promoting effect on one another.
The practical procedure in preparing the solution is simple. Chitosan and the respective chelating agent are suspended in water, in the desired ratio and in the desired amount, as pulverulent solids, preferably with vigorous stirring, the components gradually dissolving.
Ratio and amount of the solution components are selected `` 2~3~fi3;3 .... ~
according to the intended application. The properties of the solution, in particular the viscosity value, can easily be determined or, by means of simple preliminary experiments in accordance with the application, be 5 predetermined.
From the aqueous solutions containing chitosan and an acid chelating agent, these can be recovered in the form of a salt-like adduct by removal of water or by precipitation using an organic solvent. In such adducts, an ionic interaction be~ween chitosan and complexing agent, resulting from their respective cationic or anionic character, can be assumed. The removal of water is preferably carried out by means of spray drying or freeze drying, with the adduct being obtained in the form lS of a fine powder.
The precipitation of the chitosan-chelating agent adduct from the aqueous solution can easily be achieved by means of the customary organic solvent6 in which chitosan i5 typically insoluble. Examples which may be mentioned are acetone,~methanol, ethanol and isopropanol.
Redissolution of such adducts in water is easily possible without any reduction of the original solubility.
Such chitosan-chelating agent adducts are thus valuable and particularly simple to handle starting materials for preparing chitosan solutions and gels.
According to a further aspect of the invention, the abovedescribed chitosan solutions can have their viscosity drastically increased or be converted into high-viscosity gels, without additional chitosan having tlo`be introduced to the solution for this purpose. This effect can be achieved by adding salts of polyvalent metaIs and acids in which chitosa~ is only moderately soluble or insoluble to the aqueous solutions containing chikosan and an acid chelating agent. Particularly suitable salts are those of divalent metals and among these, in particular for the purposes of cosmetic, pharmaceutical and medical applications of the solutions or gels, the salts of calcium and magnesium. As acids on 213i~3a ~ - s -which these salts are based, mention may be made of, in particular, carbonic acid, sulfuric acid, phosphoric acid and oxalic acid.
To effect the viscosity increase or gel formation, appropriate salts are sLmply stirred into the chitosan solution, these dissolving more or less quickly.
The amount of salt to ~e added is non-critical within a wide range and has an upper limit imposed by the specific solubility thereof in the system. It is advantageous to use the salt in a weight ratio to the chitosan present in the solution of from 0.01 1 to 5:1 or in a molar ratio to the chelating ayent present in the solution of from 0.01:1 to 5:1. The ratio to be selected from case to case depends on the desired viscosity value, which can be determined in simple routine experLments. In the course of the dissolution process, the viscosi~ of the solution increases continuously. The final viscosities are typically from 4 to 20 times the initial viscosity.
Depending on the initial visco ity o~ the solution and the amount of the ~alt added, intermediate-viscosity to high-viscosity solutions and high-viscosity gels can be produced. This effect is presumably attributable to the cations of the salt introduced into the system binding the chelating agent more strongly, thexeby reducing the solubilizing effect of the latter on chitosan~and, in combination with the simultaneously liberated acid, reducing the solubility of the chitosan.
By means of the present invention there are thus provided, in a simple manner, chitosan solutions and gels having tailored viscosity values, in particular ones aving a~ high viscosity at a comparatively low initial concentration, for a very wide variety of application . .
~ areas.
; Example 1 ~ ;~
100 g o~ chitosan together with 70 g of ~DTA are ~ ~ added~to S 1 of demineralized water while stirring. After ; ~ stirring for 12 hours, a clear viscous solution having a ~ viscosity value of 870 cps is obtained.
2 ~ 3 ~
Example 2 In a similar way to Example 1, a solution is prepared from 100 g of chitosan and 50 g of ~7TA.
Viscosity: ~50 cps.
Example 3 In a similar way to Example 1, a solution is prepared from 100 g of chitosan and 80 g of DTPA .
ViscosityO 850 cps. ~-~
Example 4 Pulv2rulent calcium carbonate is stirred into the solutlon of E~ample 1 in a ratio of 0.5 g/100 ml of solution. The dissolution process proceeds with a small ;~
amount of gas evolution (~2)- ~he solution is then clear~ The viscosity is 3640 cps.
Example_5 Pulverulent calcium carbonate is stirred into the solution of Example 1 in a ratio of 1 gJ100 ml of solution. The solution remains turbid, since not all the calcium carbonate has yet dissolved. The viscosity is ~0 4700 cps. -After standing for 3 days at 25C, the solution ; ~
is clear. The viscosity is 15,600 cps. --Example 6 1 1 of the solution obtained in accordance with Example 1 i8 spray dried. The product obtained is a fine powder.
1 g of this powder dissolves, with stirring, in 100 ml of water within 15 minutes leaving no residue and -~
giving a viscous solution.
Example 7 il of the solution obtained in accordance with Example 1 is freeze dried in a flat layer (1 cm) to a residual moisture content of 15%. The product obtained is finely pulverized.
1 g of this powder dissolves, with stirring, in ~-100 ml of water within 15 minutes leaving no residue and - ~ -giving a viæcou5 solution.
Example 8 ;
500 ml of acetone are slowly added with vigorous ~;
, .,:
'," ~
21 3 ~ v 3 5 .. ~ .
stirring to 1 1 of the solution obtained in accordance with Example 1. The chitosan-EDTA adduct precipitates quantitatively and settles after the stirrer is turned off. The product is obtained by separating it off from 5 the solution, washing with acetone and drying. : .
1 g of the pulverized product dissolves, with stirring, in 100 ml of water within 15 minutes ~eaving no residue a~d giving a viscou~ nlution.
,' ~ ' : , ' ~','- "
~,"~ "~
: ;, .- .~. .
It has now been found that chitosan can be dissolved in water without problems in a wide concentration range if acid chelating agents are added.
Furthermore, it has been found that in such solutions the 10 visc08ity can be drastically increased up to high-viscosity gels without having to change the original chitosan concentration, if salts of polyvalent metals and acids in which chitosan is only moderately soluble or in~oluble are added to these solutions.
Finally, it has also been found that chitosan and chelating agents can be recovered in the form of a sàlt~
like adduct from a co~mon aqueous solution by removal of the water or by precipitation using an organic solvent.
This adduct can be redissolved in water without problems.
The invention accordingly provides a process for preparing aqueous solutions and gels of chitosan in which chitosan and an acid chelating agent are dissolved in water.
The invention further provides a process for preparing high-viscosity chitosan gels in which salts of polyvalent metals and acids in which chitosan is only moderately soluble or insoluble are added to aqueous solutions containing chitosan and an acid chelating agent.
The invention finally provides a salt-like adduct of ~hitosan and chelating agent which can be obtained from corresponding solutions by removal of water or by precipitation using an organic solvent.
In the process of the invention, any commercial chitosan can be used.
The acid chelating agents to be used in the process of ths invention are known per se, for instance ~rom the field of anal~tical chemistry and, in particular, from complexometric analysis. Chelating r~ 213 l 6 3 ~
agents which are suitable for the purpose of the invention are all bidentate or polydentate chelating agents which are able to form stable chelate complexes with, in particular, polyvalent metal ions. Preference is 5 given to using the readily commercially available com-plexing agents nitrilotriacetic acid (NTA), ethylene-diaminetetraacetic acid tEDTA), diethylenetriaminepenta-acetic acid (DTPA), triethylenetetraminehexaacetic acid (~T~A) or diam~nocyclohexanetetraacetic acid (DCTA).
~hese can, preferably, ~e used in the form of the free acids, but also in the form of their (partial) sodium salts. Partiaular preference is given to EDTA.
It has been found that chitosan together with such chelating agents ~an be dissolved without p~oblems in water in a wide concentration range, with the mass ratio of chitosan to the complexing agent also being largely unproblematical. ~hus, chitosan and chelating agents in a mass ratio of from 1:0.3 to 1:5 can be readily dissolved in water to give solutions having a total content of from O.l`to 2~% by weight. In the case of low-molecular-weight chitosan, even higher total contents, for instance up to about 50% by weight, are possible. These findings are very surprising, since, on the one hand, the chelating agents have only a weak acid character in comparison with the acids or acid solutions customary as solvents for chitosan and, on the other hand, these chelating agents have only a low solubility in water itself. Thus, for example, onl~ 0.5 g~l of EDTA
dissolve in water at 22.5~C; for NTA this figure is 1.28 g~l and for DTPA the figure is 3.5 g/l. It is assumed that chitosan and chelating agents have a mutually reinforcing solubility-promoting effect on one another.
The practical procedure in preparing the solution is simple. Chitosan and the respective chelating agent are suspended in water, in the desired ratio and in the desired amount, as pulverulent solids, preferably with vigorous stirring, the components gradually dissolving.
Ratio and amount of the solution components are selected `` 2~3~fi3;3 .... ~
according to the intended application. The properties of the solution, in particular the viscosity value, can easily be determined or, by means of simple preliminary experiments in accordance with the application, be 5 predetermined.
From the aqueous solutions containing chitosan and an acid chelating agent, these can be recovered in the form of a salt-like adduct by removal of water or by precipitation using an organic solvent. In such adducts, an ionic interaction be~ween chitosan and complexing agent, resulting from their respective cationic or anionic character, can be assumed. The removal of water is preferably carried out by means of spray drying or freeze drying, with the adduct being obtained in the form lS of a fine powder.
The precipitation of the chitosan-chelating agent adduct from the aqueous solution can easily be achieved by means of the customary organic solvent6 in which chitosan i5 typically insoluble. Examples which may be mentioned are acetone,~methanol, ethanol and isopropanol.
Redissolution of such adducts in water is easily possible without any reduction of the original solubility.
Such chitosan-chelating agent adducts are thus valuable and particularly simple to handle starting materials for preparing chitosan solutions and gels.
According to a further aspect of the invention, the abovedescribed chitosan solutions can have their viscosity drastically increased or be converted into high-viscosity gels, without additional chitosan having tlo`be introduced to the solution for this purpose. This effect can be achieved by adding salts of polyvalent metaIs and acids in which chitosa~ is only moderately soluble or insoluble to the aqueous solutions containing chikosan and an acid chelating agent. Particularly suitable salts are those of divalent metals and among these, in particular for the purposes of cosmetic, pharmaceutical and medical applications of the solutions or gels, the salts of calcium and magnesium. As acids on 213i~3a ~ - s -which these salts are based, mention may be made of, in particular, carbonic acid, sulfuric acid, phosphoric acid and oxalic acid.
To effect the viscosity increase or gel formation, appropriate salts are sLmply stirred into the chitosan solution, these dissolving more or less quickly.
The amount of salt to ~e added is non-critical within a wide range and has an upper limit imposed by the specific solubility thereof in the system. It is advantageous to use the salt in a weight ratio to the chitosan present in the solution of from 0.01 1 to 5:1 or in a molar ratio to the chelating ayent present in the solution of from 0.01:1 to 5:1. The ratio to be selected from case to case depends on the desired viscosity value, which can be determined in simple routine experLments. In the course of the dissolution process, the viscosi~ of the solution increases continuously. The final viscosities are typically from 4 to 20 times the initial viscosity.
Depending on the initial visco ity o~ the solution and the amount of the ~alt added, intermediate-viscosity to high-viscosity solutions and high-viscosity gels can be produced. This effect is presumably attributable to the cations of the salt introduced into the system binding the chelating agent more strongly, thexeby reducing the solubilizing effect of the latter on chitosan~and, in combination with the simultaneously liberated acid, reducing the solubility of the chitosan.
By means of the present invention there are thus provided, in a simple manner, chitosan solutions and gels having tailored viscosity values, in particular ones aving a~ high viscosity at a comparatively low initial concentration, for a very wide variety of application . .
~ areas.
; Example 1 ~ ;~
100 g o~ chitosan together with 70 g of ~DTA are ~ ~ added~to S 1 of demineralized water while stirring. After ; ~ stirring for 12 hours, a clear viscous solution having a ~ viscosity value of 870 cps is obtained.
2 ~ 3 ~
Example 2 In a similar way to Example 1, a solution is prepared from 100 g of chitosan and 50 g of ~7TA.
Viscosity: ~50 cps.
Example 3 In a similar way to Example 1, a solution is prepared from 100 g of chitosan and 80 g of DTPA .
ViscosityO 850 cps. ~-~
Example 4 Pulv2rulent calcium carbonate is stirred into the solutlon of E~ample 1 in a ratio of 0.5 g/100 ml of solution. The dissolution process proceeds with a small ;~
amount of gas evolution (~2)- ~he solution is then clear~ The viscosity is 3640 cps.
Example_5 Pulverulent calcium carbonate is stirred into the solution of Example 1 in a ratio of 1 gJ100 ml of solution. The solution remains turbid, since not all the calcium carbonate has yet dissolved. The viscosity is ~0 4700 cps. -After standing for 3 days at 25C, the solution ; ~
is clear. The viscosity is 15,600 cps. --Example 6 1 1 of the solution obtained in accordance with Example 1 i8 spray dried. The product obtained is a fine powder.
1 g of this powder dissolves, with stirring, in 100 ml of water within 15 minutes leaving no residue and -~
giving a viscous solution.
Example 7 il of the solution obtained in accordance with Example 1 is freeze dried in a flat layer (1 cm) to a residual moisture content of 15%. The product obtained is finely pulverized.
1 g of this powder dissolves, with stirring, in ~-100 ml of water within 15 minutes leaving no residue and - ~ -giving a viæcou5 solution.
Example 8 ;
500 ml of acetone are slowly added with vigorous ~;
, .,:
'," ~
21 3 ~ v 3 5 .. ~ .
stirring to 1 1 of the solution obtained in accordance with Example 1. The chitosan-EDTA adduct precipitates quantitatively and settles after the stirrer is turned off. The product is obtained by separating it off from 5 the solution, washing with acetone and drying. : .
1 g of the pulverized product dissolves, with stirring, in 100 ml of water within 15 minutes ~eaving no residue a~d giving a viscou~ nlution.
,' ~ ' : , ' ~','- "
~,"~ "~
: ;, .- .~. .
Claims (7)
1. Process for preparing aqueous solutions and gels of chitosan, characterized in that chitosan and an acid chelating agent are dissolved in water.
2. Process according to Claim 1, characterized in that the chelating agent used is nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepenta-acetic acid, triethylenetetraminehexaacetic acid or diaminocyclohexanetetraacetic acid.
3. Process according to Claim 1 or 2, characterized in that chitosan and chelating agent in a mass ratio of from 1:0.3 to 1:5 are dissolved together in water to give a solution having a total content of from 0.1 to 25% by weight.
4. Process for preparing high-viscosity chitosan gels, characterized in that salts of polyvalent metals and acids in which chitosan is only moderately soluble or insoluble are added to aqueous solutions containing chitosan and an acid chelating agent.
5. Process according to Claim 4, characterized in that the carbonates, sulfates, phosphates or oxalates of calcium or magnesium are added.
6. Process according to Claim 4 or 5, characterized in that the salts are added to solutions containing chitosan and chelating agent in a mass ratio of from 1:0.3 to 1:5 in water at a total content of from 0.1 to 25% by weight.
7. Salt-like adducts of chitosan and chelating agents obtainable from common aqueous solutions by removal of water or by precipitation using an organic solvent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4337152A DE4337152A1 (en) | 1993-10-30 | 1993-10-30 | Process for the preparation of aqueous chitosan solutions and gels |
| DEP4337152.3 | 1993-10-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2134635A1 true CA2134635A1 (en) | 1995-05-01 |
Family
ID=6501460
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002134635A Abandoned CA2134635A1 (en) | 1993-10-30 | 1994-10-28 | Process for preparing aqueous chitosan solutions and gels |
Country Status (15)
| Country | Link |
|---|---|
| EP (1) | EP0650999B1 (en) |
| JP (1) | JPH07188424A (en) |
| KR (1) | KR950011474A (en) |
| CN (1) | CN1106820A (en) |
| AT (1) | ATE182344T1 (en) |
| AU (1) | AU7750094A (en) |
| CA (1) | CA2134635A1 (en) |
| CZ (1) | CZ258694A3 (en) |
| DE (2) | DE4337152A1 (en) |
| ES (1) | ES2136688T3 (en) |
| HU (1) | HUT73013A (en) |
| NO (1) | NO944111L (en) |
| PL (1) | PL305652A1 (en) |
| RU (1) | RU94039534A (en) |
| ZA (1) | ZA948523B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6362330B1 (en) | 1997-04-05 | 2002-03-26 | Wolff Wolsrode Ag | Polysaccharide-based thermoplastic material, process for preparing the same and method of use thereof |
| WO2015120085A1 (en) * | 2014-02-04 | 2015-08-13 | Hemcon Medical Technologies, Inc. | Chitosan materials from carbonic acid solution |
| US10850003B2 (en) | 2011-11-13 | 2020-12-01 | Cresilon, Inc. | In-situ cross-linkable polymeric compositions and methods thereof |
| US11160901B2 (en) | 2015-04-10 | 2021-11-02 | Tricol Biomedical, Inc. | Bioadhesive chitosan gel for controlling bleeding and for promoting healing with scar reduction without obscuring or interfering with access to a surgical field |
| US11801671B2 (en) | 2017-01-23 | 2023-10-31 | Afyx Therapeutics A/S | Method for fabrication of a two-layered product based on electrospun fibres |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996041818A1 (en) * | 1995-06-09 | 1996-12-27 | Drohan William N | Chitin hydrogels, methods of their production and use |
| US6645947B1 (en) | 1999-05-20 | 2003-11-11 | Chitogenics, Inc. | Adhesive N, O-carboxymethylchitosan coatings which inhibit attachment of substrate-dependent cells and proteins |
| TW583190B (en) * | 2001-04-04 | 2004-04-11 | Dainichiseika Color Chem | Purified chitins and production process thereof |
| KR20010106359A (en) * | 2001-10-30 | 2001-11-29 | 조석형 | Chelate compound for animals feed |
| US7265097B2 (en) | 2002-08-20 | 2007-09-04 | Chitogenics, Inc. | Methods of drug delivery using sulphated chitinous polymers |
| CN101274099B (en) * | 2007-03-27 | 2011-03-23 | 醒能生物制品开发股份有限公司 | Method for preparing polymer matrix with transfer function |
| US8517979B2 (en) | 2008-12-22 | 2013-08-27 | Abbott Laboratories | Carriers for hemostatic tract treatment |
| US8715719B2 (en) | 2010-06-16 | 2014-05-06 | Abbott Vascular, Inc. | Stable chitosan hemostatic implant and methods of manufacture |
| SG10201808743VA (en) * | 2014-06-10 | 2018-11-29 | Dermtreat Aps | Compositions comprising electrohydrodynamically obtained fibres for administration of specific dosages of an active substance to skin or mucosa |
| JP7353980B2 (en) | 2017-01-23 | 2023-10-02 | アフリックス セラピューティクス アー／エス | Method for preparing electrospun fibers with high content of bioadhesives |
| CN110327221A (en) * | 2019-04-16 | 2019-10-15 | 中国人民解放军第四军医大学 | A kind of dentin collagen fiber demineralization material and the preparation method and application thereof |
| CN112480433A (en) * | 2020-11-30 | 2021-03-12 | 东南大学成贤学院 | Adhesive chitosan-alginate hydrogel and preparation and application methods thereof |
| CN113441513B (en) * | 2021-05-25 | 2022-07-19 | 中国地质大学（武汉） | Organic-inorganic composite material for stabilizing heavy metal waste residue and preparation method thereof |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2754796A1 (en) * | 1977-12-09 | 1979-06-13 | Wella Ag | HAIR CONDITIONER AND HAIR DETERGENT |
| DE3600333C2 (en) * | 1985-01-08 | 1996-03-28 | Agency Ind Science Techn | Membrane for the separation of liquids by evaporation |
| JPS61170376A (en) * | 1985-01-24 | 1986-08-01 | Kazuji Fukunaga | Preservative for food |
| JPH0635359B2 (en) * | 1988-03-17 | 1994-05-11 | 片倉チッカリン株式会社 | Liquid fertilizer that suppresses the occurrence of plant diseases |
-
1993
- 1993-10-30 DE DE4337152A patent/DE4337152A1/en not_active Withdrawn
-
1994
- 1994-09-19 DE DE59408512T patent/DE59408512D1/en not_active Expired - Fee Related
- 1994-09-19 AT AT94114697T patent/ATE182344T1/en not_active IP Right Cessation
- 1994-09-19 EP EP94114697A patent/EP0650999B1/en not_active Expired - Lifetime
- 1994-09-19 ES ES94114697T patent/ES2136688T3/en not_active Expired - Lifetime
- 1994-10-20 CZ CZ942586A patent/CZ258694A3/en unknown
- 1994-10-24 KR KR1019940027112A patent/KR950011474A/en not_active Application Discontinuation
- 1994-10-26 AU AU77500/94A patent/AU7750094A/en not_active Abandoned
- 1994-10-27 JP JP6263691A patent/JPH07188424A/en active Pending
- 1994-10-27 CN CN94117615A patent/CN1106820A/en active Pending
- 1994-10-28 PL PL94305652A patent/PL305652A1/en unknown
- 1994-10-28 RU RU94039534/04A patent/RU94039534A/en unknown
- 1994-10-28 ZA ZA948523A patent/ZA948523B/en unknown
- 1994-10-28 NO NO944111A patent/NO944111L/en unknown
- 1994-10-28 HU HU9403118A patent/HUT73013A/en unknown
- 1994-10-28 CA CA002134635A patent/CA2134635A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6362330B1 (en) | 1997-04-05 | 2002-03-26 | Wolff Wolsrode Ag | Polysaccharide-based thermoplastic material, process for preparing the same and method of use thereof |
| US10850003B2 (en) | 2011-11-13 | 2020-12-01 | Cresilon, Inc. | In-situ cross-linkable polymeric compositions and methods thereof |
| US11383005B2 (en) | 2011-11-13 | 2022-07-12 | Cresilon, Inc. | In-situ cross-linkable polymeric compositions and methods thereof |
| WO2015120085A1 (en) * | 2014-02-04 | 2015-08-13 | Hemcon Medical Technologies, Inc. | Chitosan materials from carbonic acid solution |
| US9925210B2 (en) | 2014-02-04 | 2018-03-27 | Tricol Biomedical, Inc. | Chitosan materials from carbonic acid solution |
| US10632143B2 (en) | 2014-02-04 | 2020-04-28 | Tricol Biomedical, Inc. | Chitosan materials from carbonic acid solution |
| US11234998B2 (en) | 2014-02-04 | 2022-02-01 | Tricol Biomedical, Inc. | Chitosan materials from carbonic acid solution |
| US11160901B2 (en) | 2015-04-10 | 2021-11-02 | Tricol Biomedical, Inc. | Bioadhesive chitosan gel for controlling bleeding and for promoting healing with scar reduction without obscuring or interfering with access to a surgical field |
| US11801671B2 (en) | 2017-01-23 | 2023-10-31 | Afyx Therapeutics A/S | Method for fabrication of a two-layered product based on electrospun fibres |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0650999B1 (en) | 1999-07-21 |
| PL305652A1 (en) | 1995-05-02 |
| NO944111L (en) | 1995-05-02 |
| CN1106820A (en) | 1995-08-16 |
| ATE182344T1 (en) | 1999-08-15 |
| AU7750094A (en) | 1995-05-18 |
| HUT73013A (en) | 1996-06-28 |
| ES2136688T3 (en) | 1999-12-01 |
| EP0650999A1 (en) | 1995-05-03 |
| KR950011474A (en) | 1995-05-15 |
| JPH07188424A (en) | 1995-07-25 |
| NO944111D0 (en) | 1994-10-28 |
| ZA948523B (en) | 1995-06-23 |
| DE4337152A1 (en) | 1995-05-04 |
| RU94039534A (en) | 1996-08-20 |
| CZ258694A3 (en) | 1995-06-14 |
| DE59408512D1 (en) | 1999-08-26 |
| HU9403118D0 (en) | 1995-01-30 |
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