Antibacterial sheet material that can be used as a wound dressing and method for producing same

Abstract

A sheet material that can be used as a wound dressing and contains elemental metal particles.

Claims

1. A method comprising: providing porcine skin; administering an alkaline and oxidative treatment to said porcine skin comprising dipping said porcine skin alternately in hydrogen peroxide and sodium hydroxide; acidifying the alkaline and oxidatively treated porcine skin with an acid selected from the group consisting of: phosphoric acid, hydrochloric acid, and acetic acid; mechanically comminuting the acidified porcine skin until a collagen-containing suspension is produced, said suspension having a solids content from 0.5 to 5%; adjusting said collagen-containing suspension to a neutral to slightly alkaline pH from 6.5 to 8.5 by adding a phosphate buffer; separately producing an elemental-metal containing suspension that is stabilized with a stabilizing agent, wherein the elemental metal particles include silver particles and have an average particle size between 10 nm and 10 m; adding the elemental-metal-containing suspension to the pH-adjusted collagen-containing suspension while promoting dispersion using a dispersion promoting means selected from the group consisting of: an ultrasonic bath, and rotor-stator mill, in order to produce a collagen and elemental metal containing suspension; drying the collagen-and-elemental-metal-containing suspension until a translucent sheet material is produced, wherein the drying of the liquid collagen-containing starting material is performed at a temperature above 20 C. under vacuum; and sterilizing the dried sheet material using ethylene oxide such that additional cross-links are produced in the sheet material, wherein the elemental metal particles are incorporated into the sheet material both at the near-surface regions and in the middle of the sheet material, wherein the sheet material has a thickness between 0.1 and 1 mm, a closed porosity of less than 50%, an elemental metal particle content from 10 to 100,000 ppm.

2. The method according to claim 1, further comprising applying the sheet material to a wound to dress said wound.

3. The method as claimed in claim 1, wherein the elemental metal particles have an average particle size of less than 50 nm.

4. The method of claim 1, wherein the sheet material has a closed porosity of less than 20%.

5. The method of claim 1, wherein the sheet material comprises more than 90% of collagen.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained in more detail with reference to FIG. 1 and FIG. 2.

(2) FIG. 1 shows a flowchart of a method for producing a collagen-containing sheet material.

(3) FIG. 2 shows a scanning electron micrograph of a sheet material useable as a wound dressing.

DETAILED DESCRIPTION

(4) First, porcine skin is prepared by an alkaline and oxidative treatment in FIG. 1.

(5) For this purpose, hydrogen peroxide and sodium hydroxide may be used, for example, in which the starting material is alternately dipped and is then rinsed.

(6) Through this wet chemical preparation, a starting material is provided which comprises more than 70%, preferably more than 80% of collagen.

(7) Then, the wet-chemically purified porcine skin is acidified. Preferably, phosphoric acid is used for this purpose, or another acid such as hydrochloric or acetic acid.

(8) To prepare a suspension, the porcine skin is first comminuted mechanically by mincing, and then an aqueous suspension is produced from the slurry resulting from further comminuting steps. This suspension in particular has a solids content from 0.5 to 5%.

(9) Then, the aqueous suspension is adjusted to a neutral to slightly alkaline pH from 6.5 to 8.5 by adding a phosphate buffer.

(10) Subsequently, a nano-silver containing aqueous suspension is added. For this purpose, a suspension should be used which is stable over a longer period. The metal is not added as a salt, but as elemental silver.

(11) To achieve a good distribution, the addition of the nano-silver containing suspension may be accomplished using suitable dispersion promoting means, for example in an ultrasonic bath, or a rotor-stator type mill.

(12) Subsequently, the suspension is dried in trays at a temperature above 20 C. under vacuum.

(13) The collagen will thereby mostly settle on the bottom of the tray as a film-like structure, with a large part of the silver particles trapped in the material being formed.

(14) Subsequently, the dried sheet material can be packaged and sterilized.

(15) Sterilization may, for example, be accomplished using ethylene oxide, whereby moreover cross-links can be produced in this way which increase the stability of the resulting material.

(16) Also, sterilization of the already packaged material is possible by irradiation. The use of ionizing radiation for sterilization is also possible.

(17) The produced material rehydrates very fast, has a good hemostatic effect, and is foldable, rollable and can be cut easily, even in its dry state.

(18) Additionally, the material is at least translucent to an extent so that the applied material permits to perceive the underlying tissue. Complications such as inflammation arising under the sheet material can be easily identified.

(19) Furthermore, the material is less prone to sticking and can be easily removed.

(20) FIG. 2 shows a scanning electron micrograph of a sheet material useable as a wound dressing, which contains about 1000 ppm of nano-silver.

(21) This material was prepared essentially according to the teachings of EP 2 098 255 A2, and after neutralization a silver nanoparticles containing suspension was added to the suspension according to the teachings of DE 10 2009 059 276 A1.

(22) In the scanning electron micrograph, silver particles were found both in surface-near regions and in the middle of the sheet material. This is attributable to the fact that the suspension is stabilized by an emulsifier, so that the silver particles uniformly distribute in the liquid precursor.

(23) Moreover it can be seen that the silver particles are mostly present in form of agglomerates, which does not affect their efficacy.