RU2480245C2 - Method for making hydrogel wound dressings - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: present invention refers to medicine, particularly to a method for making hydrogel wound dressings of polyvinylpyrrolidone or its monomer, agar, distilled water, ethylene or propylene, polyglycols, silver using ionising radiation wherein a complex of cationic polysaccharide, preferably chitosan, and silver is prepared by mixing AgNO₃ with chitosan powder characterised by an average molecular weight of 40000 to 200000, previously degraded by irradiation with beam energy 10 MeV; the deposition is filtered, washed with distilled water and added to a mixture consisting of, wt %: 2-10% of polyvinylpyrrolidone or monomer, max. 5% of agar, at least 75% of distilled water and 1-3% of ethylene or propylene polyglycols, and gel prepared thereby is cross-linked by ionizing radiation of a dose of 20-30 kGy, preferentially 25 kGy.

EFFECT: provided high biological activity and long effective use of surgical dressings.

3 cl, 6 ex

Description

An object of the present invention is a method for manufacturing hydrogel-based wound dressings containing a complex of cationic polysaccharide and silver.

Cationic polysaccharides, such as chitosan, contain an amine functional group in their structure, and have antibacterial and antitumor properties.

Silver also has bactericidal properties and has long been used as a component in the manufacture of various dressings for wounds, including burns and ulcers.

Polish patent No. 151581 discloses a method for manufacturing hydrogel-based wound dressings from synthetic and natural polymers by polymerization and stitching. Such wound dressings are characterized by high elasticity and a tight fit to the skin, which allows them to be used for various types of wounds.

A method of manufacturing a hydrogel-based wound dressings of the present invention is to obtain a complex of a cationic polysaccharide, preferably chitosan, with silver adsorbed from an aqueous solution of silver nitrate by mixing AgNO ₃ with chitosan powder, characterized by an average molecular weight of 40000-200000, previously subjected to degradation using irradiation with a beam energy of 10 MeV, which corresponds to a radiation dose in the range from 10 to 100 kGy. The resulting solution was stirred, filtered, the precipitate was washed with water and added to a mixture of synthetic and natural polymers of the same composition as described in patent No. 151581. Further, the resulting hydrogel is crosslinked by ionizing radiation at a dose of 20-30 kGy, preferably 25 kGy. The silver content in the complex with the cationic polysaccharide is from 1 to 10% by weight of the polysaccharide, while the silver content in the hydrogel is from 0.01 to 1% by weight of the hydrogel.

Tests have shown that the addition of silver to irradiated chitosan significantly increases the biological activity of the hydrogel-based material of the present invention. Biological activity is much higher compared to that in the case of dressings made by traditional methods or obtained using silver in the form of a colloidal silver solution with a concentration of 500 ppm.

The hydrogel-based material of the present invention, which is a dressing for all types of wounds, is packaged in a sealed, flat plastic packaging.

The composition as a percentage by weight of the weight of the polymer mixture in the ratio specified in Polish patent 151581, which is given here as an illustrative example of the method according to the invention, includes: 2-10% PVP (polyvinylpyrrolidone), not more than 5% agar, not less than 75 % distilled water and 1-3% ethylene polyglycol.

Example 1

A complex of chitosan with silver was obtained by adding to 4 ml of 0.1% AgNO ₃ solution 0.025 g of chitosan powder with an average molecular weight of 40,000-200,000, which had previously been degraded by irradiation with a dose of 20 kGy. The solution was stirred for 100 minutes, then filtered, and the precipitate was washed with distilled water. The complex thus obtained was introduced into 20 ml of a polymer mixture (2 ml of polyvinylpyrrolidone, 1 ml of agar, 0.5 ml of ethylene polyglycol and 16.5 ml of distilled water) and crosslinked under the influence of ionizing radiation at a dose of 25 kGy. The silver content was 0.01 wt.% By weight of the obtained hydrogel. The whole procedure was carried out with a product protected from UV radiation.

Example 2

A complex of chitosan with silver was obtained by adding 0.25 g of chitosan powder with an average molecular weight of 40,000-200,000, previously subjected to degradation by irradiation with a dose of 25 kGy, to 4 ml of a 0.1% AgNO ₃ solution. Then followed according to the procedure described in Example 1. The silver content was 0.1 wt.% By weight of the obtained hydrogel. The whole procedure was carried out with a product protected from UV radiation.

Example 3

A complex of chitosan with silver was obtained by adding 2.5 g of chitosan powder with an average molecular weight of 40,000-200,000, previously subjected to degradation by irradiation with a dose of 30 kGy, to 4 ml of a 0.1% AgNO ₃ solution. Then followed according to the procedure described in Example 1. The silver content was 0.1 wt.% By weight of the obtained hydrogel. The whole procedure was carried out with a product protected from UV radiation.

The antibacterial activity of the hydrogel-based materials thus obtained containing a complex of chitosan with silver was tested as follows.

Example 4

The hydrogel-based material obtained in Example 1 was tested for Escherichia coli, examining the area of slowdown of the growth rate of the microorganism. Under sterile conditions, 1 cm by 1 cm squares were cut. The squares were placed in plates sown with Escherichia coli, then the plates were incubated at 37 ° C. After 24 hours of cultivation, the zone of inhibition of growth of microorganisms was 1 mm

Example 5

The hydrogel-based material obtained in Example 2 was tested for Escherichia coli, examining the region of slowdown in the growth of microorganisms. Then followed the procedure described in Example 4. After 24-hour cultivation, the zone of inhibition of growth of microorganisms was 3-4 mm

Example 6

The hydrogel-based material obtained in Example 3 was tested for Escherichia coli, exploring the area of slowdown in the growth of microorganisms. Then followed the procedure described in Example 4. After 24 hours of cultivation, the zone of inhibition of growth of microorganisms was 4-5 mm

Claims (3)

1. A method of manufacturing wound dressings based on a hydrogel of polyvinylpyrrolidone or its monomer, agar, distilled water, ethylene or propylene polyglycol, silver using ionizing radiation, characterized in that the complex of cationic polysaccharide, preferably chitosan, and silver is obtained by mixing AgNO ₃ with a powder chitosan, characterized by an average molecular weight of from 40,000 to 200,000, previously subjected to degradation by irradiation with a beam energy of 10 MeV, the precipitate is filtered, washed with distilled in Doy and added to the mixture, including, wt.%: 2-10% polyvinylpyrrolidone or its monomer, not more than 5% agar, not less than 75% distilled water and 1-3% ethylene or propylene polyglycol, and the gel thus obtained is crosslinked under exposure to ionizing radiation at a dose of 20-30 kGy, preferably 25 kGy. 2. The method according to claim 1, characterized in that the silver content in complex with the cationic polysaccharide is from 1 to 10 wt.% By weight of the cationic polysaccharide. 3. The method according to claim 1, characterized in that the silver content in the thus obtained hydrogel is from 0.01-1 wt.% By weight of the hydrogel.