EP1893673A1

EP1893673A1 - Collagen-based shaped body

Info

Publication number: EP1893673A1
Application number: EP06754121A
Authority: EP
Inventors: Herbert Gord; Klaus-Dieter Hammer; Jürgen MELLE
Original assignee: Kalle GmbH and Co KG
Current assignee: Kalle GmbH and Co KG
Priority date: 2005-06-09
Filing date: 2006-06-03
Publication date: 2008-03-05
Also published as: WO2006131285A1; DE102005026747A1

Abstract

The invention relates to a method for producing collagen-based shaped bodies, collagen fibrils being homogeneously dissolved in an if appropriate aqueous amine oxide, the solution being extruded or shaped to form a prefilm and the extrudate or the prefilm being treated with an aqueous precipitation bath in which the collagen polypeptides are precipitated out and the extrudate or the prefilm is solidified to form a shaped body. The invention further relates to the shaped body itself which is produced by this method and also to use thereof as a surgical sewing material, as wound covering material or as replacement cartilage material and also as edible food casing, in particular as edible artificial sausage casing.

Description

Shaped body based on collagen

The invention relates to moldings based on collagen, a process for their preparation and the use of the moldings, in particular as a food casing or for medical purposes.

Shaped bodies of collagen fibrils are known. However, these are extremely roughly structured. They contain pores and are not sufficiently firm and supple. They can not be made to have a compact and dense structure. Alternatively, molded bodies of hydrolyzed collagen, i. made of gelatin, developed. However, the degree of hydrolysis varies greatly. The gelatin obtained in the hydrolysis is a mixture of

Polypeptide chains of different lengths and therefore different molecular weight.

Described are methods in which the normally insoluble collagen becomes an aqueous solution. In doing so, the collagen with the help of

Degraded enzymes, in particular with the aid of protein-solubilizing (proteolytic) enzymes (US-A 3 034 852, 3 121 049, 3 314 861 or 3 637 642 and GB-A 1,119,342). The degradation converts the collagen into gelatin with a broad molecular weight distribution. Mechanically resilient films can no longer be produced from this. Process for the conversion of collagen

Fiber masses in sheet-like material are also known (US Pat. Nos. 2,934,446 and 2,934,447).

Also known are films of synthetic polymers, for example of polyamide, polyolefin (in particular of polyethylene or polypropylene), polyurethane, polylactide or mixtures thereof. For medical applications, these materials are unsuitable because they are not sufficiently compatible with the body's own tissue. They remain foreign bodies and usually have to be removed because of incompatibility. If the films are used as artificial food casings, then they are not for

Co-consumption suitable. This also applies to the tubular films according to DE-A 199 61 843. For their preparation is a mixture of cellulose with one or more protein (s), for example with gelatin or collagen, dissolved in a system of NMMO / water. The solution is then shaped by extrusion bubbles and the molding solidified in an aqueous precipitation bath. In contrast, the casings made from a mixture of cellulose, a globular protein and an insoluble filler, likewise produced by the NMMO process, are edible (DE-A 101 29 5391).

It was therefore an object to provide a method for producing mechanically resilient moldings from collagen, in which the collagen can be dissolved and reprecipitated without being hydrolytic

To be exposed to degradation. The moldings should be compatible with body tissue, so that they can also be used in surgery. For use in the medical field, it is particularly important that they are free of cellulose. In addition, moldings in film form should be able to be used as artificial food casings which are suitable for co-consumption. Not only do they have to be chewable, they also have to be digestible.

In connection with this, it has been found that collagen fibrils can be homogeneously dissolved in N-methylmorpholine N-oxide monohydrate at 80 to 110 ^° C. and give a transparent, viscous solution which does not change even after prolonged heating. Treating with a precipitating fluid, such as water or a dilute aqueous NMMO solution, may cause the collagen fibrils to precipitate out again.

The present invention thus provides a process for the production of collagen-based shaped articles which is characterized in that collagen fibrils are homogeneously dissolved in an optionally hydrous amine oxide, the mass is extruded with the dissolved collagen fibrils or shaped into a prefilm in that the extrudate or the precursor film is treated with an aqueous precipitation bath liquid in which the collagen polypeptides are precipitated and the extrudate or prefilm is solidified into a shaped article.

Fibril-producing collagens belong to the multidomain proteins with 3 collagen α-chains wound into a triple helix. Unlike any other In known processes, the polypeptide chains of the collagen fibrils undergo virtually no hydrolytic degradation in the process according to the invention. They are not split but go into solution at their original length. In the first dissolution step, the numerous tropocollagens that are assembled into a fibril are separated. In the second release step, the three

Polypeptide chains, each forming a triple helix, separated from each other. The secondary and tertiary structure of the collagen is thus eliminated in the solution. Each of the peptide chains has about 1,000 amino acids linked to it. They have a length of about 2,800 Å (corresponding to 280 nm), and a thickness of about 14 Å (corresponding to 1, 4 nm). The preferred solvent for the collagen fibrils is N-methylmorpholine N-oxide monohydrate (NMMO-MH). The solution generally contains about 6 to 30% by weight of collagen, preferably about 10 to 15% by weight. Even after prolonged heating of the solution virtually no polypeptide chains are cleaved, recognizable by a constant viscosity. The viscosity of the solution is determined by the concentration of the polypeptide chains and the temperature of the solution.

By extruding the hot, viscous solution in water or a dilute aqueous amine oxide solution, the collagen can be precipitated again. The extrusion dies can be used as thread spinning nozzles, slot dies or

Ring nozzles are formed so that threads, flat films or tubular films arise. In the case of tubular films, precipitation liquid is expediently also conducted into the interior of the tubes. The structure of the precipitated collagen, and thus the mechanical properties and the permeability of the moldings, can be varied within wide limits and adapted to the particular application. The composition and the temperature also affect the structure of the precipitated collagen. The higher the amine oxide concentration in the precipitation bath, i. in particular, the higher the NMMO concentration, the slower and the more compact the polypeptide is precipitated. A very compact structure is obtained using an aqueous precipitation bath which

Contains 10 to 30 wt .-% NMMO and has a temperature of 30 to 50 ^° C. Porous films useful, for example, as a wound-covering material, on the other hand, are obtained when extruded into an aqueous precipitation bath having a lower NMMO concentration (generally less than 10% by weight). - A -

and a temperature in the range of 2 to 25 ^° C, preferably 5 to 15 ^° C. Then the polypeptide precipitates very rapidly and in a loose, porous form. The film thickness can also be selected within a wide range. It can be from 10 μm - or even less - to 100 μm and more. Preferably, the thickness is about 20 to 85 microns, more preferably 30 to 70 microns. To this

In this way, moldings can be created for a wide variety of applications.

The collagen can be replaced by up to 49%, preferably 5 to 25%, by cellulose. In exceptional cases, the collagen can even be replaced by cellulose up to 90%. The cellulose is dissolved purely physically in the aforementioned warm NMMO-MH, i. without being chemically altered. Their average degree of polymerization (DP) therefore does not decrease practically. The DP, determined by the Cuoxam method, is preferably about 300 to 900, preferably 500 to 850. In dilute aqueous amine oxide, in particular in dilute aqueous NMMO, the cellulose is also reprecipitated, together with the collagen.

By mixing finely divided, in NMMO-MH insoluble or sparingly soluble fillers prior to extrusion, the elongation at break of the moldings can be reduced, so that chewable films can be obtained. Well suited as

Fillers are, for example, bran, in particular wheat bran, ground natural fibers, in particular ground flax, hemp or cotton fibers, cotton linters, guar gum, locust bean gum, powdered SiO ₂ and / or ground calcium carbonate. The maximum diameter of the filler particles should preferably be not more than 100 .mu.m, preferably not more than 65 .mu.m. The proportion of filler is generally 3 to 50 wt .-%, preferably 4 to 40 wt .-%, each based on the dry weight of the film. By the addition of hydrophilic additives, the chewability can be further improved. The additives are generally soluble in NMMO-MH. Preferred additives are starch and starch derivatives, such as starch acetate, chitin,

Chitosan or pectin; Heteropolysaccharides and derivatives thereof, such as carrageenan, xanthan, alginic acid or alginate; Finally, also toxicologically harmless synthetic polymers, such as polyvinylpyrrolidone or polyvinyl alcohol. The proportion of hydrophilic additives is generally about 0.5 to 15 wt .-%, preferably about 1 to 10 wt .-%, each based on the total weight of the film.

The spinning solution is generally not extruded directly into the precipitation bath, but previously passes through an air gap. The air gap has expediently a length of a few millimeters up to 10 cm or even more. In the air gap, a tubular extrudate can be inflated and stretched by an internal gas pressure. The orientation of the polypeptide chains in the longitudinal direction, which prevails immediately after the extrusion, can thereby be changed. If the polypeptide chains are arranged by stretching on average at an angle of 45 ° to the extrusion direction, then a film with uniform properties in the longitudinal and transverse directions is obtained.

After leaving the spinning bath, the shaped body is washed with water until it is free of amine oxides. This is expediently carried out in a countercurrent process.

Depending on the intended use, the molded article, in particular the film, can still be impregnated with a plasticizer, such as glycerol or sorbitol.

The molding - with or without plasticizer - is then usually dried, for example by hot air.

Thicker films, in particular those for medical and surgical purposes, can be produced by cast film processes. The dope is poured into the desired thickness in a mold, the molded mass then treated with Fällbadflüssigkeit and finally washed until the cast film is free of amine oxides. In this way can be foils of several millimeters

Thickness (up to about 10 mm), which can then be processed into cartilage replacement material. The moldings can be further modified, for example by treatment with lubricants. These are in particular triglycerides of long-chain fatty acids, such as stearic acid or erucic acid. Also suitable are natural waxes, for. B. carnauba wax. Such lubricant-containing films can inter alia as cartilage replacement material, the friction in joints, for example in artificial

Hip joints, diminish. Films to be used as wound cover can also be made porous with the addition of slightly water-soluble salts, such as sodium lactate or sodium hydrogen carbonate, which are then dissolved out.

Novel, particularly well-tolerated suture materials, biocompatible wound-covering materials, medical films and tubes can be produced in a simple and cost-effective manner by the method according to the invention.

In addition, edible, ie suitable for co-consumption, packaging materials for food can be produced by the process according to the invention. In particular, these are edible sausage casings. You can serve as a serving for sausages, sausage or sausage. They then generally have a dry tensile strength of 22 to 35 N / mm ² in the longitudinal direction and

18 to 30 N / mm ² in the transverse direction, and a wet tensile strength of 5 to 10 N / mm ² in the longitudinal direction and 3 to 8 N / mm ² in the transverse direction. The tear strength is therefore significantly lower in the wet state than in the dry state. The elongation at break when wet is about 10 to 20% in the longitudinal direction and about 25 to 30% in the transverse direction, in the dry state about 10 to 30% in the longitudinal direction and about 20 to 25% in the transverse direction.

Finally, the present invention also relates to the shaped bodies themselves produced by the process according to the invention.

The following examples serve to illustrate the invention. Percentages are by weight unless otherwise stated or directly apparent from the context. example 1

1, 2 kg digested collagen fibrils were stirred into 12.7 l of a 60% aqueous NMMO solution. The mixture was adjusted to pH 11 with NaOH and stabilized with 2.2 g of propyl gallate. In a container with stirrer was then at a reduced pressure of about

25 mbar and increasing temperature distilled off water until the aqueous

NMMO solution was converted almost completely into NMMO monohydrate.

This corresponds to an NMMO concentration of 87%. Was received on this

Make a transparent, yellowish dope with a refractive index of 1, 4820 and a zero shear viscosity of 7,100 Pa s at 85 ^° C.

The dope was then at a temperature of 90 ^° C by a

Annular gap nozzle extruded with a diameter of 40 mm. The tube thus obtained passed through a 10 cm long air gap, in which it was held wrinkle-free by supporting air acting from inside, before it entered the precipitation bath.

The precipitation bath consisted of a 25% aqueous NMMO solution which had been heated to 25 ° C. Precipitation bath liquid of the same composition also reached the interior of the film tube The level of this so-called inner bath was kept at approximately the same level as that of the outer bath The tubing was passed through a pulley placed near the bottom of the precipitating bath, thus passing through an effective felling distance of 3 m, the tube being stretched so far that its flat width after leaving the spinning vat 70 mm was. He went through after 8 wash vats, each with 8 deflection rollers, m a bath depth of 2.5, and m is an air gap of 0.5. at the end of the last Waschkufe warm water of 80 ⁰ C was introduced, which was conducted in countercurrent At the end, the hose was passed through a softener blade, in which was a 5% aqueous glycerol solution, which was kept at 60 ^° C. When leaving the Glycerinkufe the hose had a flat width of 50 mm. Subsequently, the tube was dried in the inflated state with hot air. The air required for inflation was kept stationary with two nip rolls. While The drying was followed by a transverse stretching, so that the flat width of the tube after leaving the dryer was 70 mm. The dryer had several zones of different temperature. At the entrance of the dryer, the temperature was 120 ^° C. Until the outlet of the dryer, the temperature gradually fell to 80 ^° C. The drying was carried out to a final moisture content of about 10 to 12% After leaving the dryer, the tube was again up to 16 18% moistened and then rolled up in flattened form.

By cutting the tubes could produce films with a width of 140 mm and virtually any length. They were very supple and resistant to abrasion. The thickness of the films was about 40 microns.

Example 2

1.0 kg of collagen fibrils were stirred into 12 l of a 60% aqueous NMMO solution, the mixture was adjusted to pH 11 with NaOH, and 2.0 g of propyl gallate were added for stabilization. The mixture was then slowly heated in a stirred kettle at a reduced pressure of about 25 mbar, with water distilling off until the level of NMMO monohydrate was reached. This corresponds to a share of 87% NMMO and 13% water. The transparent, yellowish dope thus produced had a refractive index of 1.4820 and a zero shear viscosity of 7,200 Pa.s at 85 ^° C. It was then extruded at a temperature of 95 ^° C. through an annular die having a diameter of 40 mm. As in Example 1, the hose passed through a 10 cm long air gap, in which it was kept wrinkle-free by supporting air acting from inside.

The precipitation of the polypeptides was then carried out by treating the tube from the inside and the outside in a bath containing a 10% aqueous NMMO solution, which was heated to 10 ^° C. Under these conditions, the polypeptide spontaneously precipitated and assumed a porous structure. The felling distance was again 3 m, the tube was deflected in the same way halfway. After leaving the spinning vat, the flat width of the hose was 64 mm. It was followed by an intensive washing process, in which the hose passed 8 skids with 8 pulleys. Water was in the Passed countercurrently through the wash baths. The temperature increased to 80 ⁰ C in the last wash. The tube was then dried as described in Example 1 in a hot air dryer to a final moisture content of 10 to 12%. He was then wound up in flattened form.

The tube had a wall thickness of about 55 microns. Slicing was used to produce films, which were used i.a. suitable as wound cover.

Example 4 4.48 kg of wheat bran (particle size smaller than 63 μm) became a 60 in 68 kg

% aqueous NMMO solution stirred. To the suspension was then added 3.2 kg of collagen fibrils. By adding NaOH, a pH of 11 was set. For stabilization, an additional 12 g of propyl gallate were added. In a stirred tank with internals to increase the shear, water was distilled off at reduced pressure (25 mbar) and increasing temperature until the aqueous NMMO was present as NMMO monohydrate. The spinning mass thus obtained had a refractive index of 1, 4885 and a zero shear viscosity of 7,100 Pa s, each determined at 85 ^° C. At a temperature of 90 ⁰ C, the spinning mass through a ring die with a diameter of 20 mm and a gap width of 0 Extruded 5 mm. The tubular extrudate passed through a 10 cm long air gap, in which it was kept wrinkle-free by compressed air acting from inside. He then entered a precipitation bath containing 15 ^° C tempered 15% aqueous NMMO solution. The same cooled precipitation bath liquid was also introduced into the interior of the tube with the level of the inner precipitation bath being maintained at about the same level as that of the outer bath. The Innenfällbad was continuously renewed, as in all other examples. Overall, the hose passed through a felling path with a length of 3 m, where it was deflected at half distance by a roller located at the bottom of the bath. The hose was then stretched so far that he had a flat width of 35 mm when leaving the spinning vat. He then went through 4 wash skates with a total of 8 top and bottom pulleys. The wash baths each had a depth of 2.5 m and an air gap of 0.5 m. At the end of the last skid water was introduced, which then in countercurrent through the Was skimmers led. In this way, the NMMO content at the exit of the 1st Waschkufe was maintained at 12 to 16%. The temperature rose to 60-70 ° C. in the last wash, and finally the hose was passed through a softener vat containing a 10% aqueous solution of glycerine, leaving the glycerine vial with a flat width of 35 mm The air needed for inflation was held between two sets of squeeze rollers as described above, the hot air dryer had several temperature zones, the temperature decreasing from one zone to the next, and the temperature in the entry zone was still 120 ° ^C C it fell to 80 ^° C. up to the initial zone and was then rewetted to a moisture content of 8 to 12% and wound up in flattened form The finished casing showed a dry tensile strength of 28.5 N / mm ² in the longitudinal direction and 22, 5 N / mm ² in the transverse direction and a wet tensile strength of 7.5 N / mm ² in the longitudinal direction and 5.5 N / mm ² in the transverse direction one to

Filling with sausage meat to bring more suitable form of packaging, he was shirred in sections. For this purpose, the moisture content was increased to 16 to 18% before shirring.

The Raffraupen were then on an automatic filling, portioning and

Clip device filled with sausage meat, steamed and smoked. The characteristics of the sausages were just as good as those of sausages in the usual skin fiber intestines.

Example 4

0.8 kg of collagen fibrils and 0.2 kg of cellulose were stirred into 12 l of a 60% aqueous NMMO solution, the mixture was adjusted to pH 11 with NaOH, and 2.0 g of propyl gallate were added for stabilization. The mixture was then slowly heated in a stirred kettle at a reduced pressure of about 25 mbar with water distilling off until the solvent was virtually pure NMMO monohydrate. This corresponds to a share of 87% NMMO and 13% water. The transparent, yellowish dope produced in this way had a refractive index of 1.4830 and a Zero shear viscosity of 6,050 Pa s at 85 ⁰ C. The further processing was carried out as described in Example 2.

The precipitation was then carried out by treating the tube from the inside as well as from the outside in a bath containing a 10% aqueous NMMO solution on

10 ^° C was tempered. Under these conditions, the solids precipitated spontaneously. The felling distance was again 3 m, the tube was deflected in the same way halfway. After leaving the spinning vat, the flat width of the hose was 64 mm. It was followed by an intensive washing process, in which the hose passed 8 skids with 8 pulleys. Water was passed countercurrently through the wash baths. The temperature increased to 80 ^° C in the last wash. The tube was then dried as described in Example 1 in a hot air dryer to a final moisture content of 10 to 12%. He was then wound up in flattened form.

The hose was excellently suited as a sausage casing and, when cut open, could also be used for other packaging purposes, in particular in the food sector.

Claims

claims

1. A process for the production of moldings based on collagen, characterized in that collagen fibrils are dissolved homogeneously in an optionally aqueous amine oxide, the mass is extruded with the dissolved collagen fibrils or formed into a prefilm, the extrudate or the prefilm with an aqueous precipitation bath liquid is treated, in which the collagen polypeptides are precipitated and the extrudate or the prefilm is solidified into a shaped body.

2. The method according to claim 1, characterized in that is used as the amine oxide N-methyl-morpholine N-oxide, preferably N-methyl-morpholine N-oxide monohydrate.

3. The method according to claim 2, characterized in that a solution with 6 to 30 wt .-%, preferably 10 to 15 wt .-%, of collagen in N-methyl morpholine N-oxide monohydrate is used.

4. The method according to claim 1, characterized in that up to 49%, preferably 5 to 25%, of the collagen are replaced by cellulose.

5. The method according to one or more of claims 1 to 4, characterized in that the solution contains 3 to 50 wt .-%, preferably 4 to 40 wt .-%, each based on the dry weight of the film produced therefrom, of filler.

6. The method according to claim 5, characterized in that the filler of particles having a diameter not more than 100 microns, preferably not more than 65 microns, consists.

7. The method according to claim 5 or 6, characterized in that the filler wheat bran, ground hemp, flax or cotton fibers, Cotton linters, guar gum, locust bean gum, powdered silica and / or ground calcium carbonate.

8. The method according to one or more of claims 1 to 7, characterized in that the shaped body, the shape of a thread, a

Flat film or a tubular film is formed.

9. The method according to one or more of claims 1 to 8, characterized in that an aqueous precipitation bath with up to 30 wt .-% NMMO is used.

10. The method according to one or more of claims 1 to 9, characterized in that the aqueous precipitation bath is maintained at a temperature of 5 to 50 ^° C.

11. The method according to one or more of claims 1 to 10, characterized in that the extrudate passes through an air gap before it enters the precipitation bath.

12. The method according to claim 11, characterized in that the air gap has a length of 2 to 20 cm, preferably from 3 to 12 cm.

13. The method according to claim 11, characterized in that the extrudate is tubular and is cross-stretched in the air gap.

14. The method according to one or more of claims 1 to 13, characterized in that the shaped body is washed after treatment with the Fällbadflüssigkeit, preferably with water until it is virtually free of amine oxides.

15. The method according to one or more of claims 1 to 14, characterized in that the molding is impregnated with a plasticizer, preferably glycerol or sorbitol.

16. The method according to one or more of claims 1 to 15, characterized in that the molding is modified with lubricants, preferably with triglycerides of long-chain fatty acids, and / or with natural waxes.

17. Shaped body, obtainable by a process according to one or more of claims 1 to 16.

18. Use of a shaped body according to claim 17 as a surgical suture, as Wundabdeckmaterial or as a cartilage replacement material.

19. Use of the moldings according to claim 17 as an edible food casing, in particular as an edible artificial sausage casing.