Production of materials having an anisotropic structure
The present invention relates to a process for the production of a multi-layered material having anisotropic pores. It further relates to a multi-layered material which can be produced by the process according to the invention, and to the use of a multi-layered material as a chondral support matrix, a meniscus support matrix or an intervertebral disc support matrix.
1. A process for the production of a multi-layered material having anisotropic pores, the process comprising the steps of:
(a) providing a temperature gradient between two temperature-controllable bodies arranged opposite one another;
(b) arranging in the temperature gradient a first substance containing at least one sublimable compound and solidifying the first substance to form a first layer;
(c) arranging in the temperature gradient a second substance containing at least one sublimable compound adjacent to the first substance and solidifying the second substance to form a second layer adjacent to the first layer;
(d) subliming the sublimable compounds of the adjacent first and second layers to form a monolithic support matrix of the first and second layers having pores generated by the subliming, the pores extending continuously and anisotropically throughout the first and second layers of the monolithic support matrix, and the pores penetrating the first and second layers of the support matrix; and
(e) consolidating the support matrix,
wherein the arranging of the second substance is conducted over the first substance, side-by-side with the first substance, or concentrically around the first substance without the solidifying of the first and second substances being interrupted.
2. The process of claim 1 , wherein the temperature gradient is between 0.5 K/mm and 200 K/mm.
3. The process of claim 2 , wherein the temperature gradient is between 2.5 K/mm and 25 K/mm.
4. The process of claim 2 , wherein the temperature gradient is between 5 K/mm and 15 K/mm.
5. The process of claim 1 , wherein the first and/or the second substance, independently of each other, contains at least one polymer or monomers thereof.
6. The process of claim 5 , wherein the polymer is selected from the group consisting of peptides, proteins, polysaccharides, and mixtures thereof.
7. The process of claim 6 , wherein the polymer is a protein, and the protein is a structural protein.
8. The process of claim 1 , wherein the sublimable compound of the first and/or the second substance, independently of each other, is selected from the group consisting of aqueous solvents, polar solvents, non-polar solvents, organic acids, organic bases, mineral acids, and mineral bases.
9. The process of claim 1 , wherein the sublimable compounds of the first substance and the second substance are the same sublimable compound.
10. The process of claim 1 , wherein at least one of the temperature-controllable bodies has a microstructuring.
11. The process of claim 1 , further comprising the step of:
arranging a layer of functionalized polymer fibres on the support matrix as an outermost layer.
12. The process of claim 1 , wherein the consolidating is carried out by wet chemical crosslinking, dehydrothermal processes, enzymatic crosslinking, non-enzymatic glycation, UV irradiation, gamma irradiation, sintering, infiltration, or a combination thereof.
13. The process of claim 1 , wherein as a result of the solidifying of the second substance adjacent to the first substance, crystals of the sublimable compounds grow uniformly successively throughout the first and second layers, and wherein the crystals are removed as a result of the subliming so as to leave the continuous and anisotropic pore structure in the support matrix.
14. The process of claim 1 , wherein the support matrix is a chondral support matrix, an osteochondral support matrix, a meniscus support matrix, or an intervertebral disc support matrix.
15. The process of claim 1 , wherein the first and second layers of the support matrix differ in composition, functionality, and physical properties.
16. The process of claim 1 ,
wherein step (c) further comprises arranging in the temperature gradient a third substance containing at least one sublimable compound adjacent to the second substance and solidifying the third substance to form a third layer adjacent to the second layer,
wherein step (d) further comprises subliming the sublimable compound of the third layer to form the monolithic support matrix additionally of the third layer, the pores extending anisotropically throughout the first, second, and third layers of the monolithic support matrix, and the pores penetrating the first, second, and third layers of the support matrix, and
wherein the arranging of the third substance is conducted without the solidifying of the first, second, and third substances being interrupted.
17. The process of claim 16 , wherein the first, second, and third layers of the support matrix differ in composition, functionality, and physical properties.
18. The process of claim 16 , wherein the arranging of the third substance is conducted over the second substance, side-by-side with the second substance, or concentrically around the second substance.
19. The process of claim 16 , wherein the pores extend throughout the first, second, and third layers of the support matrix.