BIODEGRADABLE MEMBRANE

Abstract

The invention relates to a biodegradable membrane on the basis of an organic-inorganic hybrid polymer, and to a process for producing same.

Claims

1-21. (canceled)

22. A method of producing a biodegradable membrane from an organic-inorganic hybrid polymer, the method comprising: (a) producing an inorganic sol by stirring a solution containing at least an aqueous solvent, an alkoxy silane, and an acid at a temperature of at least 20° C.; (b) converting the sol to a polymer-sol mixture by addition of an end group functionalized biodegradable organic polymer or by addition of a precursor of the polymer to the sol; and (c) applying the polymer-sol mixture to a front side of a film and hardening the mixture to form a hybrid polymer layer, wherein, in an additional step (d), a plurality of fibers are introduced into the mixture before hardening the mixture.

23. The method in accordance with claim 22, wherein the plurality of fibers are introduced into the mixture in step (d) by: (i) distributing fibers on the front side of the film before the application of the mixture; or (ii) distributing the fibers on a surface of the applied mixture.

24. The method in accordance with claim 22, wherein steps (c) and (d) are performed multiple times respectively alternately after one another.

25. The method in accordance with claim 22, wherein the solution in step (a) is stirred at a temperature of 20 to 50° C.

26. The method in accordance with claim 22, wherein the polymer-sol mixture is stirred between step (b) and step (c) for a duration of 0.5 minutes to 45 minutes.

27. The method in accordance with claim 22, wherein the mixture in step (c) is applied by spread coating or by flooding the front side of the film.

28. The method in accordance with claim 22, wherein the alkoxy silane is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, and mixtures thereof.

29. The method in accordance with claim 22, wherein the end group functionalized biodegradable organic polymer is selected from the group consisting of end group functionalized polyesters, end group functionalized polyalcohols, end group functionalized polyoxazolines, end group functionalized polyanhydrides, end group functionalized polysaccharides, end group functionalized polyhydroxyalkanoates, end group functionalized proteins, and mixtures thereof.

30. The method in accordance with claim 22, wherein the acid is a sulfonic acid, a mineral acid, or a mixture thereof, and/or the solution in step (a) has a pH between 1 and 7.

31. The method in accordance with claim 22, wherein the aqueous solvent is water or a mixture of water and an alcohol, tetrahydrofuran, or toluene.

32. The method in accordance with claim 22, wherein the polymer in step (b) is added to the inorganic sol in a weight ratio of 0.1 to 10.0.

33. The method in accordance with claim 22, wherein the fibers are selected from the group consisting of silica gel fibers, fibers containing TiO.sub.2, polyester fibers, polyanhydride fibers, polysaccharide fibers, polyhydroxyalkanoate fibers, protein fibers, and mixtures thereof.

34. The method in accordance with claim 22, wherein the fibers have a diameter of 1 nm to 2 mm.

35. The method in accordance with claim 22, wherein the membrane is released from the front side of the film after a drying time of at least 30 minutes.

36. The method in accordance with claim 22, wherein at least one pharmacologically active compound is added in step (a) or (b) or is impregnated into the hybrid polymer layer after the hardening.

37. A membrane comprising a biodegradable organic-inorganic hybrid polymer and a plurality of fibers.

38. The membrane in accordance with claim 37, wherein the membrane disintegrates and/or degrades when contacted with a physiological solution.

39. The membrane in accordance with claim 37, which, after 8 days of contact with an aqueous PBS solution, the membrane disintegrates or degrades to at least 10 wt % of its total mass.

40. A barrier for growth of human or animal cells comprising a membrane in accordance with claim 37, which forms a barrier for growth for a period of at least 3 days.

41. A membrane produced in accordance with a method of claim 22.

42. A method of surgically preventing formation of adhesion or scarring in a postoperative patient, comprising applying a membrane of claim 37 to the patient postoperatively.

Description

[0069] There are furthermore shown:

[0070] FIG. 1: a photograph of two membranes in accordance with the invention;

[0071] FIG. 2: a diagram on the resilience of membranes in accordance with the invention;

[0072] FIG. 3: SEM photographs on the degradation of membranes in accordance with the invention;

[0073] FIG. 4: degradation profiles of different membranes; and

[0074] FIG. 5: SEM photographs of surfaces of membranes in accordance with the invention.

[0075] FIG. 1 shows fiber reinforced membranes that were cut to size from a DIN A4 film and that were already removed from the substrate. They are membranes that were produced in accordance with Example 1 (2-R) and Example 2 (5-R). The fiber reinforced membrane is intrinsically stable, flexible, and has a homogeneous structure.

[0076] FIG. 2 shows a diagram from which it can be seen that the resilience of the membranes produced in accordance with the invention is improved with the increasing proportion of organic polymer in the hybrid polymer layer. If twice the mass or five times the mass of organic polymer relative to the inorganic sol is used in the production process, the resulting membrane also remains intact after multiple bending with a small bending diameter. If the mass ratio of organic polymer to inorganic sol in the hybrid polymer layer is only 1:1, approximately 75-90% of all membranes rupture after 10× folding with a bending diameter of 14 mm. The trial results shown in FIG. 2 here relate exclusively to the membranes that, in accordance with the invention, are fiber reinforced and are biodegradable. Membranes that are not fiber reinforced cannot be handled. They rupture so easily that no bending trials at all could be performed.

[0077] FIG. 3 shows three SEM photos a), b), and c) of a membrane that has been produced in accordance with Example 1 and has subsequently been wetted with a physiological solution. The film surface is still very homogeneous in FIG. 3a, that shows a non-degraded film. After 7 days, the film surface gradually dissolves such that the integrated fibers are exposed (cf. photograph in FIG. 3b). After 64 days, the fibers have been removed from the membrane (cf. photograph in FIG. 3c). The membrane has here, however, not contracted, but has retained its original shape. The degradation of the membrane does not, however, progress further even after 64 days (not shown).

[0078] FIG. 4 shows degradation profiles of different membranes in accordance with the invention in a phosphate-buffered saline solution over a period of 64 days. The rectangular measurement points represent a membrane that was produced in accordance with Example 1. The triangular measurement points were found with a membrane that was produced in accordance with Example 2. The degradation data of the membranes that were produced in accordance with Method 2 using Mixtures 1 and 2 are behind the pentagonal and hexagonal measurement points respectively.

[0079] FIG. 5 shows SEM photographs of surfaces of two membranes in accordance with the invention. They are largely transparent for visible light and have a smooth surface structure.