EP1778303A1

EP1778303A1 - A wound dressing material of dibutyrylchitin and chitin reconstituted therefrom

Info

Publication number: EP1778303A1
Application number: EP05730837A
Authority: EP
Inventors: Izabella Krucinska; Lidia Szosland; Romualda Cislo; Anna Blasinska; Agnieszka Komisarczyk; Andrzej Chilarski; Jadwiga Bilska; Bogdan Pilas
Original assignee: Politechnika Lodzka
Current assignee: Politechnika Lodzka
Priority date: 2004-04-13
Filing date: 2005-04-07
Publication date: 2007-05-02
Also published as: WO2005099781A1; PL367163A1; WO2005099781A8

Abstract

The subject of the present invention is a wound dressing material, a wound ressing, an application of dibutyrylchitin and chitin reconstituted from dibutyrylchitir in the production of a wound dressing, and a method of producing a wound dressing material and a wound dressing. The subjects of the present invention serve to produce a wound dressing material of arbitrary size and shape.

Description

A WOUND DRESSING MATERIAL OF DIBUTYRYLCHITIN AND CHITIN RECONSTITUTED THEREFROM

10

15

The subject of the present invention is a wound dressing material, a wound dressing, an application of dibutyrylchitin and chitin reconstituted from dibutyrylchitin 20 in the production of a wound dressing, and a method of producing a wound dressing material and a wound dressing. The subjects of the present invention serve to produce a wound dressing material of arbitrary size and shape.

Chitin is a natural polymer, whose biological properties have been established in 25 the course of scientific research. The basic characteristic of this polymer, which influence its subsequent workability, is its low solubility in organic solvents. Chitin and its derivatives can occur independently or in a mixture with other pharmacologically admissible additives, as well as with compounds with documented therapeutic activity. To facilitate the modification of chitin, the polymer chain must be modified. One 30 of the modifications is to produce an esterified derivative of chitin, dibutyrylchitin. Dibutyrylchitin is obtained by way of the estrification of chitin, mostly of animal origin, with butyryl anhydrate. The dibutyrylchitin obtained is soluble in organic solvents, such as acetone, ethanol, methyl chloride, dimethulsulphoxide, N-methylpyrolidone or dimethylformamide. The significant property is the ability of dibutyrylchitin to revert 35 into the form of reconstituted chitin. Reconstituted chitin is obtained through the alkaline hydrolysis of dibutyrylchitin. Dibutyrylchitin fibres are highly biocompatible with a living organism, just like chitin, they biodegrade and accelerate wound healing. These properties have been confirmed with both in vitro and in vivo studies. Experiments using aqueous extracts of dibutyrylchitin fibres, show that these extracts do not exhibit haemolytic, cytotoxic nor dermal irritant activity. In biodegradability studies of dibutyrylchitin in the presence of lysozyme it was determined that the biodegradation process occurs on the fibre surface, at a rate comparable to that of chitin. Other chitin derivatives are known, of which the best known is chitozan. This polymer is a fundamental raw material in the production of bandaging tissues, such as those produced by ENSAI Co. Ltd. of Japan. The brand name Chitopack C encompasses chitozan fibres, termed cotton-like, 2 - 20 mm long and 20-50 μm along the cross-section and 3-15 μm across the cross-section, which are used to make fibrous wound dressings. A dressing under the name of Besc tin from U ITIKA Co. is produced in the form of a fibre mat from crab chitin. There are also reports of attempts to apply a membrane of mycogenic chitin (Sacchachitin membrane) onto a fibrous material. The membrane is produced based on an extract from the fungus Ganoderma Tsuage, which contains ca. 40% chitin. Another type of fibrous material are Chitopoly fibres produced by Fuji Spinning Co. Ltd. These are Polinosic-type fibres with a surface layer of chitozan. All of the above mentioned dressings in the form of fibrous mats are produced from cut fibres using a method of fleece formation similar to that of papermaking. There are methods in use of applying chitin or its derivatives in the form of membranes. ENSAI Co. Ltd. has marketed two wound dressings called Chitipack S and Chitipack P. Chitipack S contains marine-derived chitin in the form of foam, whereas in Chitipack P chitin it is formed into bundles. The hydrocolloid dressing, Tegasorb, from 3M is composed of a dispersion of polyisobutayrylene and chitozan particles. Patent description KR9504916 (published 1995.05.16) presents a method of producing membranes from chitin and its derivatives. The homogenous surface of the membrane and its many beneficial physical properties were obtained through the exchange of components of the coagulation bath, used in the coagulation of chitin and its derivatives. The coagulation fluid was composed of water, ethyl ether, and metal salts with a mass ratio of 9 : 1 : 0.05-0.3. The metal salts were calcium carbonate or lithium carbonate. The chitin derivatives were chitozan, ethylchitin, acetylchitin, butyrylchitin and propionylochitin. Patent description JP5345834 (published 1993.12.27) presents an antibacterial and antifungal porous polyurethane material. The material was obtained through the incorporation of polyurethane resin with 0.5-5% by mass of purified, reconstituted granular, porous chitozan, such that the porous structure was preserved. Preferentially, the chitozan is obtained through the addition of an acidic aqueous solution of chitozan to the base solution through dripping, so as to form reconstituted chitozan spheres, such that they are then washed with water and sprayed. Patent description JP2002363083 (published 2002.12.18) presents an aerosol for spraying onto wounds. This preparation is obtained through the filling of a tank with particles of highly particulated matter in solid state, with a low molecular mass, and reconstituted chitozan with an average molecular mass of 10,000-200,000, with a particle diameter of 1.0-11.0 μm in solid form, with a particle diameter variance coefficient of 0.50-1.35. Patent description CA2050873 (published 1998.06.30) describes a method of producing chitozan sulphonate, in which the hydroxyl groups at positions C3/C6 are selectively sulphonated with inexpensive sulphonating agents, containing dissolved or saturating chitozan in acetic acid and water. Chitozan is regenerated with an alkaline aqueous solution, washed with water and then alcohol. It is then soaked in a polar solvent, the solvent is pressed out and subsequently the chitozan is sulphonated with the SO3-DMF or ClHSO3an -DMF complex in a non-polar solvent. The product is removed through filtration. Patent description JP6211903 (published 1994.08.02) describes the production of chitozan sulphate of high purity and high viscosity, as well as of a sulphonating agent for chitozan. Patent description JP63210101 (published 1988.08.31) described a method of producing ultra pure, porous chitozan and chitin molecules. Patent description PL 169077 (published 1994.01.24) describes a method of producing dibutyrylchitin. Dibutyrylchitin is obtained by way of the estrification of chitin, usually from krill, with butytyl anhydrate. The technique of producing fibres using a traditional wet weaving approach is the subject of patent PL187224 (published 1998.12.21), which describes a method of producing dibutyrylchitin fibres from weaving solutions into aqueous coagulation baths. The weaving solution also contains a plasticizing agent, in addition to the polymer and solvent. The solvent is usually one of the classic organic solvents: acetone, methanol, ethanol, dimethylformamide, dimethylacetamide or dimethylsulphoxide. The plasticizing agent used was glycerol or ethylene polyglycol. The dibutyrylchitin concentration in the solution was 5-30 parts by mass, and 1-10 parts by mass of plasticizer. Such a solution is pumped through into the coagulation bath, containing water or an aqueous solution of solvent. The solidified fibre is sfretched in a water bath at a temperature of 80°C to a length of 50-500% . Patent description US 4651725 (published 1987.03.24) describes a wound dressing material composed of chitin derivative fibres, and a minimal tensile strength of 2 g/d. The chitin fibres are mixed with binding fibres, where the latter are highly biocompatible. At the same time, these fibres cannot degrade with wound seepage, this solution describes the following polymers: vinyl polyalcohol, carboxymethylcellulose, acryl acid esters, vinyl acetate, vinyl acetate copolymers, vinyl chloride, natural or synthetic rubber, as well as gelatine and starch. The by mass fraction of chitin fibres in relation to linking fibres is from 80:20 to 95:5.

The wound dressing uses a polymer obtained from the armour of crustaceans or insects. It is prepared in hydrochloric acid and caustic soda in order to remove calcium and proteins. As a result of subsequent chemical modifications the following chitin derivatives are obtained: partially deacetylated (chitozan), etherified, esterified, carboxymethylated and hydroxyethylated.

Chitin fibres are obtained by way of wet weaving from a polymer solution, using a solvent matching side groups occurring on the polymer chain. The length of the fibres produced is in the range of 3 - 20 mm. The proposed linking fibres have a linear mass of 0,1 - 50 d and a length of 0,5 - 150 mm. The fleece is produced using the papermaking method. Drying is performed on a roller press, over 3 - 20 minutes and a temperature of 100 - 180°C. Patent description JP8092820 (published 1996.04.09) describes a method of producing chitin fibres and membranes. The method is based on producing alkaline chitin with an addition of 10-48%) NaOH, pressing and the addition of carbon disulphide. These procedures result in the production of chitin xanthogenate, and subsequently chitin viscose. Fibres are produced by way of the classic wet weaving viscose method, and a foil is produced using the classic cellophane foil manufacturing method. Patent description US 3903268 (published 1975.09.02) describes a method of producing a wound dressing material composed of a mixture of chitin fibres, partially depolymerised chitin and chitin derivatives. In this solution, chitin is referred to as poly(N-acetyloglucosamine), which is a component of insect, arthropod and crustacean armor, as well as being present in certain groups of fungi. The misture of chitin and its derivatives can be introduced into the wound in the form of pills, a cream or powder. Chitin powders or solutions and those of its derivatives can serve as raw materials for the impregnation of surgical gauze, or as underlayers to be placed on wounds. The amount of chitin placed on a wound varies between 2 - 10 mg/cm² of dressing surface. Furthermore, chitin in the form of alkalichitin xanthogenate can be dissolved and converted into fibres, and thence reconstituted into the initial chitin. Partially deacetylated chitin filaments and chitin fibres can be transformed according to patent description US2040880. Chitin fibres can be used as surgical sutures or as a raw material for the production of woven or non-woven wound dressing materials, according to description US3196075. They can also be transformed into creams or suspensions. Despite the above described studies on the production of wound dressing materials, the application of chitin and its derivatives as wound dressings, there is still a need to produce effective tools facilitating the easy production of wound dressings, the perfection of technological processes and amelioration of the end product. These materials may also be used as medical implants, including in the form of wound dressings or as wound-adjacent layers in composite dressings. The goal of the present invention is to deliver means which could be used in the production of wound dressings using dibutyrylchitin and chitin reconstituted from dibutyrylchitin in order to obtain wound dressings characterised by biodegradability in contact with a living organism. The realisation of such a stated goal and solving of problems described in the state of the art connected with the production of wound dressing materials facilitating improvement in healing; at the same time characterised by biodegradability on contact with a living organism; the production of preparations enabling the use of dibutyrylchitin as a wound dressing material in therapy have all been achieved the present invention. Wound dressings being the subject of the present invention belong to the groups of prophylactic and therapeutic dressings. Therapeutic dressings are wound dressings showing medicinal properties in the removal of pathological states in the human organism at the site of their application. Prophylactic dressings are wound dressings which prevent the formation of pathological changes in the human organism in areas endangered by such changes. For example, a treatment wound dressing will be one applied to bedsores, in order to cure them. A prophylactic dressing, however, will be one which will prevent necrosis in cases of blood flow deficiency.

The subject of the present invention is a wound dressing material, composed of a mixture of synthetic and/or natural fibres, characterised in that it contains at least one

- of: dibutylchitin or butylchitin with varying esterification degrees, produced by the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin. Preferentially, a wound dressing material contains fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin. Preferentially, the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%>. Preferentially, a wound dressing material is saturated and/or coated with a dibutylchitin solution.

Preferentially, a wound dressing material is saturated and/or coated with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents. Preferentially, the dry mass dibutylchitin content per 1 m² of wound dressing surface represents from 1 to 300%> of the mass of initial wound dressing prior to the application of dibutylchitin.

Preferentially, a wound dressing material is designed to be used on wounds.

Preferentially, it is designed as a material for prophylaxis. The next subject of the present invention is a wound dressing composed of a mixture of synthetic and/or natural fibres, characterised in that it contains at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin Preferentially, that contains the fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin.

Preferentially, the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%.

Preferentially, it is saturated and/or covered with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents. Preferentially, the dry mass dibutylchitin content per 1 m of wound dressing surface represents from 1 to 300%> of the mass of initial wound dressing prior to the application of dibutylchitin.

Preferentially, it is designed for use on wounds.

Preferentially, it is a clinical dressing. Preferentially, it is a prophylactic dressing.

Preferentially, it is in the form of flakes, a sheet, a drape or a bandage composed of a mixture of synthetic and/or natural fibres. Preferentially, it is a dressing for securing a wound surface, particularly against excess non-renal fluid loss.

Preferentially, it is a dressing for accelerating healing. The next subject of the present invention is an application of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin in the production of wound dressings.

Preferentially, a mixture of synthetic and/or natural fibres are used in the production of the wound dressing. Preferentially, the fibres at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin are used in the production of wound dressings.

Preferentially, the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%>.

Preferentially, the fibre mixture is saturated and/or coated with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents to obtain 1 to 300% dibutylchitin dry mass per lm² in relation to the initial mass of the wound dressing prior to the application of dibutylchitin.

Preferentially, dressings composed of the fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin secure a wound surface against excess non-renal fluid loss. The next subject of the present invention is a method of producing a wound dressing from a mixture of synthetic and/or natural fibres, characterised in that the material is saturated and/or coated with a dibutylchitin solution.

Preferentially, the material is saturated and or coated with a solution of dibutylchitin in an organic solvent or a mixture of organic solvents.

Preferentially, the material is saturated and/or coated with a solution of dibutylchitin in an organic solvent to obtain from 1 to 300% of dibutylchitin dry mass per lm² in relation to the initial mass of wound dressing prior to the application of dibutylchitin.

Preferentially, the material with an applied layer of dibutylchitin is set aside to allow the solvent or mixture of solvents to evaporate.

Preferentially, the material with an applied layer of dibutylchitin is immersed in a coagulation bath containing a coagulant, until such time as it solidifies and is dried. Preferentially, the material with an applied layer of dibutylchitin is additionally processed in alkali following the removal of solvent or mixture of solvents.

Preferentially, the material contains a layer of butylchitin estrified between 10% and

95%, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin. Preferentially, the material contains a layer of chitin reclaimed from dibutylchitin. The next subject of the present invention is a method of producing a wound dressing characterised in that the electroweaving and polymer solution spraying techniques are used in the production of the wound dressing containing dibutylchitin.

Preferentially, an electrostatic field of 2 to 35 kN is applied during the formation of fibres using the electroweaving technique, where the solidified fibres are accumulated on the collecting electrode.

Preferentially, the fibres or fibrous material composed of dibutylchitin is transformed into fibres of fibrous material composed of reconstituted chitin, using alkaline hydrolysis. Preferentially, a solution of polymer in an organic solvent or mixture of organic solvents is used during the formation of fibres using the spraying technique.

Preferentially, the solidification of the polymer is carried out at a temperature higher than the evaporation temperature of the solvent or solvent mixture.

Preferentially, polymer solidification is carried out in a coagulation bath. The next subject of the present invention is a method of producing a wound dressing characterised in that the in the production of the wound dressing hydrolysis of dibutyrylochitin to chitin is used.

Preferentially, the reconstituted chitin content following hydrolysis amounts to 1 -

100%. Preferentially, the hydrolysis is performed in a hydrolysing bath in the presence of 0,1 -

50% ΝaOH.

Preferentially, the hydrolysis is performed in a hydrolysing bath in the presence of 1-

5% ΝaOH.

Preferentially, the temperature is between 20°C and 100°C. Preferentially, the time of hydrolysis is 10 to 5h. The next subject of the present invention is a method of producing a wound dressing in the form of flakes, sheet, drape or bandage from a mixture of synthetic and/or natural fibres, characterised in that the material is saturated and/or coated with a dibutylchitin solution. Preferentially, the material is saturated and/or coated with a dibutylchitin solution in an organic solvent or mixture of organic solvents.

Preferentially, the material is saturated and or coated with a dibutylchitin solution in an organic solvent or mixture of organic solvents to obtain between 1 and 300% of the dibutylchitin dry mass per lm² in relation to the initial wound dressing mass prior to dibutylchitin application.

Preferentially, the material with an applied dibutylchitin layer is set aside to allow the solvent or mixture of solvents to evaporate. Preferentially, the material with an applied layer of dibutylchitin is immersed in a coagulation bath containing a coagulant until such time as it solidifies and is dried.

Preferentially, the material with an applied layer of dibutylchitin is additionally processed in alkali following the removal of solvent or mixture of solvents.

Preferentially, butylchitin estrified between 10% and 95% is used, which is obtained through the alkaline hydrolysis of ester moieties in dibutylchitin.

Preferentially, chitin reconstituted from dibutylchitin is used. The next subject of the present invention is a method of producing a wound dressing characterised in that the electroweaving or polymer solution spraying techniques are used in the production of a wound dressing containing dibutylchitin. Preferentially, an electrostatic field of 2 to 35 kN is applied during the formation of fibres using the electroweaving technique, where the solidified fibres are accumulated on the collecting electrode.

Preferentially, the formed dibutylchitin fibres or fibrous material is transformed into butylchitin fibres of fibrous material estrified between 10%> and 95%o or reconstituted chitin, obtained through the alkaline hydrolysis of dibutylchitin.

Preferentially, a solution of polymer in an organic solvent or mixture of organic solvents is used during the formation of fibres using the spraying technique.

Preferentially, the solidification of the polymer is carried out at a temperature higher than the evaporation temperature of the solvent or solvent mixture. Preferentially, polymer solidification is carried out in a coagulation bath.

The figures enclosed facilitate a better explanation of the nature of the present invention.

Figure la represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with dibutyrylchitin 7 days after the operation. A scab is visible at the top. Below the scab is freshly formed epithelium, and below it is lattice-like connective tissue with many cells. HE staining, mag. 120 x

Figure lb represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with dibutyrylchitin 14 days after the operation. On the left is a strip of epithelium covering granular tissue. HE staining, mag. 120 x

Figure lc represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with dibutyrylchitin 21 days after the operation. On the left is a strip of epithelium covering fibrous tissue. HE staining, mag. 120 x Figure 2a represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with chitin 7 days after the operation. On the right is a skin fragment with migrating cells. On the left is a scab, below which is newly formed epithelium. HE staining, mag. 120 x Figure 2b represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with chitin 14 days after the operation. Young connective tissue covered with epithelium is visible. HE staining, mag. 120 x

Figure 2c represents a micrograph of deep skin lesions bandaged with a polypropylene dressing covered with chitin 21 days after the operation. Connective tissue covered with epithelium is visible. HE staining, mag. 120 x

Figure 3a represents a micrograph of deep skin lesions bandaged with a gauze dressing (control) 7 days after the operation. Skin fragment with lesion. HE staining, mag. 120 x Figure 3b represents a micrograph of deep skin lesions bandaged with a gauze dressing (control) 21 days after the operation. On the left is connective tissue covered at the edge with epithelium, which is lacking in the center. HE staining, mag. 120 x

Figure 4a represents an image of a wound prior to the application of a flake composed of 100% dibutyrylchitin fibres.

Figure 4b represents an image of a wound following the application of a flake composed of 100% dibutyrylchitin fibres. Figure 4c represents the healing process of a wound bandaged with flakes of dibutyrylchitin fibres.

Figure 4d represents a wound following treatment with a dibutyrylchitin dressing.

Figure 5a represents a wound prior to the application of a dressing composed of 100% dibutyrylchitin fibres. Figure 5b represents a wound prior to the application of a dressing composed of 100% dibutyrylchitin fibres.

Figure 5c represents a wound following the application of a dibutyrylchitin flake.

Figure 5d represents a healing wound following the application of a dibutyrylchitin flake. Figure 5e represents a wound during healing.

Figure 6a represents a wound following the demarcation of necrotic tissue.

Figure 6b represents a wound following the application of dibutyrylchitin flakes.

Figure 6c represents healing under a dibutyrylchitin flake.

Below are example embodiments of the present invention, defined above. Example 1. A method of producing a wound dressing material using the polymer spraying technique

A 10%) dibutyrylchitin solution in ethanol was heated to 22°C and forced through a weaving nozzle with a 0,4 mm bore. The viscosity of a dibutyrylchitin solution in dimethylacetamide at 25°C was [D] = 2.41 dl/g. The polymer temperature in the mixer was 22°C, whereas the pumping temperature (nozzle temperature) was 25°C. The nozzle was 2 m from the receiving surface. Technological air at 25 °C was blown on the polymer strands. The air flow was applied at 36 d Vs, and the polymer at 9,5 c Vs. The polymer was placed in a coagulation bath coagulation bath (water). The last stage consisted of drying in a drier at 100°C for 2 min. A fleece was obtained of fibres 0,053 mm thick on average and a high fibre thickness variability (ca. 45%). The fibrous tissue obtained had a mass per surface area of 20 g/m² and had an absorption capacity of 0,02 g/g and sorption rate of 0,36 g/g-s.

Example 2. A method of producing a wound dressing material using polymer solution spraying

A 15%) dibutyrylchitin solution in ethanol was prepared, with a viscosity in dimethylacetamide at 25°C of [η] = 2.41 dl/g. Such a weaving solution was heated to 25°C and forced through 0,4 mm bore nozzles. The pumping temperature (nozzle temperature) was 30°C. The nozzle was 2 m from the receiving surface. Air at 22°C was blown on the polymer strands at 40 dmVs, and the polymer at 23 cm³/s. The polymer was completely solidified in a coagulation bath coagulation bath (water). A fleece was obtained with fibres 0,09 mm thick on average and a thickness variability of 45%>. The fibrous tissue obtained had a mass per surface area of 38 g/m² and had an absorption capacity of 0,021 g/g and sorption rate of 0,40 g/g-s.

Example 3. A method of saturating a prophylactic wound dressing material with a dibutyrylchitin solution.

A polypropylene fibre mat with a mass per surface area of 30 g/m produced with the direct polymer solution spraying was washed in distilled water with a surface-active additive. After wringing, the fibre mat was washed several times in distilled water, and then in ethanol. An enhancing bath was prepared, containing an 8.9% dibutyrylchitin solution in acetone using a polymer with a solution viscosity of [η] = 1,57 dl/g at 25°C. The prepared fibre mat was inserted into the enhancing bath containing the dibutyrylchitin solution in acetone, at ambient temperature. Excess polymer solution was removed with a roller press with a force of 0,7129 N/cm. The sample was dried at ambient temperature. A prophylactic wound dressing material was obtained, with a d.m. dibytulchitin content of 35,71%. The material obtained was stiffer than the initial material.

Example 4. A method of coating a wound dressing material with a dibutyrylchitin solution

Dibutyrylchitin with a viscosity in dimethylacetamide of [η] = 1,6 dl/g at 25°C was used to prepare the solution. The 4% dibutyrylchitin solution in ethanol was applied to a transfer tissue at a level to ensure 10 g/m² of dibutyrylchitin and air-solidified at ambient temperature. The foil obtained was coated with the same dibutyrylchitin solution at 5 g/m². A polypropylene fibre mat with a mass per surface area of 17 g/m² was applied to the unsolidified polymer layer. The system was left to evaporate at ambient temperature. The material obtained was characterised by a higher flexibility and higher permeability to water than that obtained in Example 3.

Example 5.

A woven fibre mat, 60g/m²' composed of DBC fibres was hydrolysed in Sodium base. The mat fibre was introduced into the bath between two teflon meshes, and the hydrolysis was performed at 22°C. The NaOH concentration in the bath was 4,9%>. the hydrolysis was performed in two bouts of lh 40min. Following hydrolysis, the fibre mat was rinsed in distilled water, until such time as the bath water was of neutral pH, and the fibre surface was also neutral. The fibre mat obtained was composed of chitin and dibutyrylchitin with a pure chitin concentration of 20%>. The mass per surface area after hydrolysis was 21,7g/m².

Example 6. Reconstitution of chitin from dibutyrylchitin

A polypropylene fibre mat with a mass per surface area of 30 g/m² produced by the direct polymer solution spraying technique was washed in distilled water with a surface active additive. After wringing, the fibre mat was washed several times in distilled water, and then in ethanol. An enhancing bath was prepared, containing an 8.9%> dibutyrylchitin solution in acetone using a polymer with a solution viscosity of [η] = 1,57 dl/g at 25°C. The prepared fibre mat was inserted into the enhancing bath containing the dibutyrylchitin solution in acetone, at ambient temperature. The prepared fibre mat was inserted into the enhancing bath containing the dibutyrylchitin solution in acetone, at ambient temperature. Excess polymer solution was removed with a roller press with a force of 0,7129 N/cm. The substrate with the applied dibutyrylchitin layer was heated to 50°C. It was then soaked in 5% aqueous NaOH for 15 minutes at 90°C. After the alkaline bath, the product was washed until it reached a neutral pH. The product was then rinsed with ethanol and dried at ambient temperature. Biological studies of the reconstituted chitin confirmed the lack of cytotoxicity, no skin irritation, and showed a positive influence of chitin on healing.

Example 7. A method of producing a wound dressing material using electroweaving

9 g of dibutyrylchitin powder was dissolved in 100 ml of ethanol. After the solution was clarified, the upper electrode tank of the electroweaver was filled. This tank terminated in a 1.2 mm diameter capillary. The lower, aluminium electrode was flat. With an applied voltage of 10 kN, the stream of dibutyrylchitin solution flowed to the lower electrode, at first straight and then in a spiral fashion, accelerated by the electrostatic field. The solvent evaporated concurrently. The solidified fibres with a diameter of 1 μm were collected on the lower electrode as a fibrous material. The distance between the electrodes was 21 cm.

Example 8. Animal studies

Irritation studies were performed on White New Zealand albino rabbits in accordance with PN-EN ISO 10993-10: „The biological evaluation of medical products. Examination of irritating and allergenic properties".

The experiments were performed using extracts. Polar and non-polar extracts were made, with physiological saline and sesame oil respectively, from polypropylene fibres coated with dibutyrylchitin (40% by mass of coating polymer) and reconstituted chitin (30%) by mass of coating polymer). The extracts were prepared at a rate of 120 cm² total surface per 20 ml extracting agent, and incubated at 37°C for 72 h. After this time, the samples were cooled to RT and after thorough mixing, the supernatant was decanted from the precipitate. Control samples were prepared from physiological saline and sesame oil incubated in the same conditions as the experimental samples. Prior to the study, 6 rabbits (3 animals per extract of each wound dressing material) were shaved on either side of the spine. On the day of the experiment, 5 cutaneous injections of experimental extracts and solvents were made, at 0,2 ml. Skin change evaluations were performed 24, 48 and 72 h after the injection.

No skin changes were observed at 24, 48 and 72 h following the injection of polar and non-polar extracts and their respective controls, neither in the form of reddening nor rash. The Initial Irritation Index for the polar and non-polar extracts of polypropylene dressings coated with dibutyrylchitin and chitin was 0,00. The influence on deep skin lesion healing in rabbits

A study on the influence of dressings containing dibutyrylchitin and reconstituted chitin on healing of skin lesions were performed on 16 white New Zealand rabbits, of uniform body masses, 3.2-3.5 kg. A day prior to the experiment, dorsal skin on the rabbits was depilated, over an area of 10x15 cm. 4 oval lesions 12 mm in diameter were made on each rabbit using a surgical knife. The wounds on the left side of the spine (controls) were bandaged with sterile gauze, where as the right fore wound was dressed with a chitin-coated polypropylene dressing and the right rearward with dibutyrylchitin. The wound dressings applied were additionally secured with a gauze bandage. Every 24 h until scab formation, the healing process was observed and the wounds were re-dressed. After scab formation, the scabbed-over lesions were secured with a gauze bandage. The appearance of the wounds was monitored daily and photographic documentation was made. The animals were dissected 7, 10, 14 and 21 days after the operation, 4 rabbits at a time. During the section, a careful visual examination was made of the external appearance, and following preparation of the skin, from the inside as well. Photographic documentation was made. The dorsal skin fragments containing the wounds were fixed in 8%> formaldehyde for 48 h. Next, the fixed tissues were sectioned along the wound diameter, and the sections thus obtained underwent standard histological preparation: dehydration in an acetone series, xylene saturation and paraffin imbedding. The histological slides were stained with haematoxylin and eosin according to van Gieson and Mallory.

Microscopic analysis results

Deep skin lesions dressed with a dibutyrylchitin-coated polypropylene wound dressing Seven days after the operation, skin fragments were visible in histological sections. Pink masses were visible in the lesion area, and among them numerous lymphocytes and erythrocytes. In van Gieson-stained sections, numerous proliferating fibroblasts were visible in dermal connective tissue. A migrating epithelium was observed on the edge of the wound, and overtop of it scabbing. The newly formed epithelium was present over quite an extensive area (Fig. la). Fourteen days after the operation, young connective tissue with numerous blood vessels was visible under the microscope, entirely covered with stratified squamous epithelium, hi some places, a scab was visible over the centre of the lesion, h van Gieson stained slides, numerous red-stained, parallel collagen fibres were visible, hi Mallory-stained slides, red-stained elastic fibres became visible (Fig. lb). Twenty one days after the operation, fibrous connective tissue completely covered with stratified squamous epithelium was visible in all HE and Mallory-stained slides. (Fig. lc). Deep skin lesions dressed with a chitin-coated polypropylene wound dressing

The histological appearance the of healing of wounds bandaged with a chitin-coated polypropylene dressing was very similar to the processes occurring underneath a dibutyrylchitin-coated dressing. Seven days following the operation, a skin fragment covered with epithelium became visible, where the latter migrated underneath homogenously staining masses (scabs), hi the connective tissue, basic-staining erythrocytes and lymphocytes were visible, as were infrequent granulocytes. The bottom of the wound was filled with an amorphous mass, h Mallory-stained slides, these were blue and pink. This identifies them as a mixture of mucus and fibrinogen (Fig. 2a). Fourteen days following the operation, young connective tissue was visible in most of the slides, completely covered with a stratified squamous epithelium. Quite numerous collagen fibres were visible in the connective tissue. In Mallory-stained slides, blue-stained, regular, parallel collagen fibres were visible. These fibres were less visible in the centre of the wound. Furthermore, individual bundles of elastic fibres were also visible. In a few individual cases, the centre of the young connective tissue was not covered with an epithelium, h these places, homogenous masses (scabs) were visible on its surface (Fig. 2b). Twenty one days following the operation, young, fibrous connective tissue was visible in all histological slides. In van Gieson and Mallory stained slides, numerous parallel and densely packed collagen fibres and individual elastic fibres were visible. The newly formed connective tissue was vascularised with thin-walled blood vessels (Fig. 2c).

Deep skin lesions bandaged with a gauze dressingy Seven days following the operation, dermis fragments were visible in histological slides stained with HE, covered with a stratified squamous epithelium. At the incision site, an abscess was visible covered with an amourphous mass, and numerous exfravascular erythrocytes and mononucleocytes, lymphocytes, were visible, as were individual neutrophylic lobed granulocytes. Epithelium migration from the wound edges was minimal. The bottom of the wound was filled with homogenous masses. In Mallory-stained slides, the masses were blue, and in a few places pink. This indicated that the homogenous masses are a mixture of mucus and fibrinogen (Fig. 3 a). Twenty one days following the operation the skin lesion was filled with fibrous connective tissue. In Mallory stained slides, numerous blue-stained, densely packed collagen fibres were visible. Furthermore, individual elastic fibres were visible, which stained red. The connective tissue described was in most cases covered with a squamous epithelium. In certain slides, though, epithelium was lacking in the centre of the wound, and the connective tissue therein contained fewer collagen fibres and had a higher proportion of cells (Fig. 3b).

The microscope analyses showed that wound dressings coated with both dibutyrylchitin and reconstituted chitin, do not irritate the tissue, and significantly enhance the healing of wounds. The inflammatory phase is shorter, less pronounced and epithelium proliferation is faster than in gauze-bandaged wounds.

Example 9. Clinical trial Case 1. Open fracture of the left tibia with a skin abscess in a boy, 10 years old. Operative treatment was successful, leaving a partial wound with a bare tibia at the bottom of the wound. Following the application of a bandage containing only dibutyrylchitin fibres, the would underwent autoregeneration. The treatment process is outlined in Figs. 4a - 4d.

Case 2. 2A/2B burns to the legs. Boy, 9 months old. Flakes of dibutyrylchitin fibres were applied to clean burned surfaces (no necrosis or infection), healing beneath the scab occurred without signs of infections. The treatment is pictured in Figs. 5a - 5e.

Case 3. Inner thigh dermal wound, following demarcation of necrotic tissue. Boy, 13 years old. A leaf of dibutyrylchitin fibres was applied immediately following demarcation. After a week, a significant decrease in the area of missing skin was observed. Healing occurred without complications until complete healing. The treatment is pictured in Figs. 6a - 6c.

Materials composed of pure dibutyrylchitin and reconstituted chitin, obtained via methods according the present invention can biodegrade completely or partially in contact with a living organism, i.e. in the form of wound dressing materials or as the lesion-adjacent layer of a composite wound dressing. Materials composed of dibutyrylchitin were evaluated at the Department of Experimental Surgery Biomaterial Trials of the Medical Academy of Wroclaw. The trials were performed in accordance with the European Norm ISO 10993 - „Biological evaluation of medical products". It was determined that all parameters were evaluated within norms, and that they adhere to the standards. With the permission of the Medical Ethics Committee, the influence of the materials produced according to the present invention on various types of wounds on the human body. It was determined that they do not cause any side effects, and in 8 cases out of 11 show a tendency to accelerate healing and biodegrade, as shown in the enclosed figures.

Claims

Patent Claims

1. A wound dressing material, composed of a mixture of synthetic and/or natural fibres, characterised in that it contains at least one of: dibutylchitin or butylchitin with varying esterification degrees, produced by the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin.

2. A wound dressing material according to Claim 1, characterised in that it contains fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin

3. A wound dressing material according to Claim 1, characterised in that the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%.

4. A wound dressing material according to Claim 1, characterised in that it is saturated and/or coated with a dibutylchitin solution.

5. A wound dressing material according to Claim 1, characterised in that it is saturated and/or coated with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents.

6. A wound dressing material according to Claim 1, characterised in that the dry mass dibutylchitin content per 1 m² of wound dressing surface represents from 1 to 300%> of the mass of initial wound dressing prior to the application of dibutylchitin.

7. A wound dressing material according to Claim 1, characterised in that it is designed to be used on wounds.

8. A wound dressing material according to Claim 1, characterised in that it is designed as a material for prophylaxis.

9. A wound dressing composed of a mixture of synthetic and/or natural fibres, characterised in that it contains at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin

10. A wound dressing according to Claim 9, characterised in that contains the fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin.

11. A wound dressing according to Claim 9, characterised in that the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%.

12. A wound dressing according to Claim 9, characterised in that it is saturated and/or covered with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents.

13. A wound dressing according to Claim 9, characterised in that the dry mass dibutylchitin content per 1 m² of wound dressing surface represents from 1 to 300% of the mass of initial wound dressing prior to the application of dibutylchitin.

14. A wound dressing according to Claim 9, characterised in that it is designed for use on wounds.

15. A wound dressing according to Claim 9, characterised in that it is a clinical dressing.

16. A wound dressing according to Claim 9, characterised in that it is a prophylactic dressing.

17. A wound dressing according to Claim 9, characterised in that it is in the form of flakes, a sheet, a drape or a bandage composed of a mixture of synthetic and/or natural fibres.

18. A wound dressing according to Claim 9, characterised in that it is a dressing for securing a wound surface, particularly against excess non-renal fluid loss.

19. A wound dressing according to Claim 9, characterised in that it is a dressing for accelerating healing.

20. Application of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin in the production of wound dressings.

21. An application according to Claim 20, characterised in that a mixture of synthetic and/or natural fibres are used in the production of the wound dressing.

22. An application according to Claim 20, characterised in that the fibres at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin are used in the production of wound dressings.

23. An application according to Claim 20, characterised in that the percentage composition of fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin amounts to between 0,1 and 100%.

24. An application according to Claim 20, characterised in that the fibre mixture is saturated and/or coated with a dibutylchitin solution, preferentially a solution containing an organic solvent or a mixture of organic solvents to obtain 1 to 300% dibutylchitin dry mass per lm² in relation to the initial mass of the wound dressing prior to the application of dibutylchitin.

25. An application according to Claim 20, characterised in that dressings composed of the fibres of at least one compound selected from among dibutylchitin or butylchitin with varying esterification degrees, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin, or chitin reclaimed from dibutylchitin secure a wound surface against excess non-renal fluid loss.

26. A method of producing a wound dressing from a mixture of synthetic and/or natural fibres, characterised in that the material is saturated and/or coated with a dibutylchitin solution.

27. A method according to Claim 26, characterised in that he material is saturated and/or coated with a solution of dibutylchitin in an organic solvent or a mixture of organic solvents.

28. A method according to Claim 26, characterised in that the material is saturated and/or coated with a solution of dibutylchitin in an organic solvent to obtain from 1 to 300% of dibutylchitin dry mass per lm in relation to the initial mass of wound dressing prior to the application of dibutylchitin.

29. A method according to Claim 26, characterised in that the material with an applied layer of dibutylchitin is set aside to allow the solvent or mixture of solvents to evaporate.

30. A method according to Claim 26, characterised in that the material with an applied layer of dibutylchitin is immersed in a coagulation bath containing a coagulant, until such time as it solidifies and is dried.

31. A method according to Claim 26, characterised in that the material with an applied layer of dibutylchitin is additionally processed in alkali following the removal of solvent or mixture of solvents.

32. A method according to Claim 26, characterised in that the material contains a layer of butylchitin estrified between 10% and 95%, obtained through the alkaline hydrolysis of ester moieties in dibutylchitin.

33. A method according to Claim 26, characterised in that the material contains a layer of chitin reclaimed from dibutylchitin.

34. A method of producing a wound dressing characterised in that the electroweaving and polymer solution spraying techniques are used in the production of the wound dressing containing dibutylchitin.

35. A method according to Claim 34, characterised in that an electrostatic field of 2 to 35 kN is applied during the formation of fibres using the electroweaving technique, where the solidified fibres are accumulated on the collecting electrode.

36. A method according to Claim 34, characterised in that the fibres or fibrous material composed of dibutylchitin is transformed into fibres of fibrous material composed of reconstituted chitin, using alkaline hydrolysis.

37. A method according to Claim 34, characterised in that a solution of polymer in an organic solvent or mixture of organic solvents is used during the formation of fibres using the spraying technique.

38. A method according to Claim 34, characterised in that the solidification of the polymer is carried out at a temperature higher than the evaporation temperature of the solvent or solvent mixture.

39. A method according to Claim 34, characterised in that polymer solidification is carried out in a coagulation bath.

40. A method of producing a wound dressing characterised in that the in the production of the wound dressing hydrolysis of dibutyrylochitin to chitin is used.

41. A method according to Claim 40, characterised in that the reconstituted chitin content following hydrolysis amounts to 1 - 100%>.

42. A method according to Claim 40, characterised in that the hydrolysis is performed in a hydrolysing bath in the presence of 0,1 - 50%> ΝaOH.

43. A method according to Claim 40, characterised in that the hydrolysis is performed in a hydrolysing bath in the presence of l-5%> ΝaOH.

44. A method according to Claim 40, characterised in that the temperature is between 20°C and 100°C.

45. A method according to Claim 40, characterised in that the time of hydrolysis is 10 to 5h.

46. A method of producing a wound dressing in the form of flakes, sheet, drape or bandage from a mixture of synthetic and/or natural fibres, characterised in that the material is saturated and/or coated with a dibutylchitin solution.

47. A method according to Claim 46, characterised in that the material is saturated and/or coated with a dibutylchitin solution in an organic solvent or mixture of organic solvents.

48. A method according to Claim 46, characterised in that the material is saturated and/or coated with a dibutylchitin solution in an organic solvent or mixture of organic solvents to obtain between 1 and 300% of the dibutylchitin dry mass per lm² in relation to the initial wound dressing mass prior to dibutylchitin application.

49. A method according to Claim 46, characterised in that the material with an applied dibutylchitin layer is set aside to allow the solvent or mixture of solvents to evaporate.

50. A method according to Claim 46, characterised in that in that the material with an applied layer of dibutylchitin is immersed in a coagulation bath containing a coagulant until such time as it solidifies and is dried.

51. A method according to Claim 46, characterised in that the material with an applied layer of dibutylchitin is additionally processed in alkali following the removal of solvent or mixture of solvents.

52. A method according to Claim 46, characterised in that butylchitin estrified between 10% and 95% is used, which is obtained through the alkaline hydrolysis of ester moieties in dibutylchitin.

53. A method according to Claim 46, characterised in that chitin reconstituted from dibutylchitin is used.

54. A method of producing a wound dressing characterised in that the electroweaving or polymer solution spraying techniques are used in the production of a wound dressing containing dibutylchitin.

55. A method according to Claim 54, characterised in that an electrostatic field of 2 to 35 kN is applied during the formation of fibres using the electroweaving technique, where the solidified fibres are accumulated on the collecting electrode.

56. A method according to Claim 54, characterised in that the formed dibutylchitin fibres or fibrous material is transformed into butylchitin fibres of fibrous material estrified between 10%> and 95%> or reconstituted chitin, obtained through the alkaline hydrolysis of dibutylchitin.

57. A method according to Claim 54, characterised in that a solution of polymer in an organic solvent or mixture of organic solvents is used during the formation of fibres using the spraying technique.

58. A method according to Claim 54, characterised in that the solidification of the polymer is carried out at a temperature higher than the evaporation temperature of the solvent or solvent mixture.

59. A method according to Claim 54, characterised in that polymer solidification is carried out in a coagulation bath.