Control of pore structure and size in freeze-dried collagen sponges.

Because of many suitable properties, collagen sponges are used as an acellular implant or a biomaterial in the field of tissue engineering. Generally, the inner three-dimensional structure of the sponges influences the behavior of cells. To investigate this influence, it is necessary to develop a process to produce sponges with a defined, adjustable, and homogeneous pore structure. Collagen sponges can be produced by freeze-drying of collagen suspensions. The pore structure of the freeze-dried sponges mirrors the ice-crystal morphology after freezing. In industrial production, the collagen suspensions are solidified under time- and space-dependent freezing conditions, resulting in an inhomogeneous pore structure. In this investigation, unidirectional solidification was applied during the freezing process to produce collagen sponges with a homogeneous pore structure. Using this technique the entire sample can be solidified under thermally constant freezing conditions. The ice-crystal morphology and size can be adjusted by varying the solute concentration in the collagen suspension. Collagen sponges with a very uniform and defined pore structure can be produced. Furthermore, the pore size can be adjusted between 20-40 microm. The thickness of the sponges prepared during this research was 10 mm.

[1]  I. Heschel,et al.  Dendritic ice morphology in unidirectionally solidified collagen suspensions , 2000 .

[2]  W. Kühnel,et al.  Development of a biocomposite to fill out articular cartilage lesions. Light, scanning and transmission electron microscopy of sheep chondrocytes cultured on a collagen I/III sponge. , 1999, Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft.

[3]  J. Steadman,et al.  A clinical study of collagen meniscus implants to restore the injured meniscus. , 1999, Clinical orthopaedics and related research.

[4]  F. Korkusuz,et al.  A novel osteochondral implant. , 1999, Biomaterials.

[5]  M. Spector,et al.  Meniscus cells seeded in type I and type II collagen-GAG matrices in vitro. , 1999, Biomaterials.

[6]  M. Pitman,et al.  Chondrocyte transplantation using a collagen bilayer matrix for cartilage repair. , 1997, The Journal of bone and joint surgery. British volume.

[7]  A. Mehl,et al.  Preclinical and clinical studies of a collagen membrane (Bio-Gide). , 1997, Biomaterials.

[8]  H. Takita,et al.  Pore size of porous hydroxyapatite as the cell-substratum controls BMP-induced osteogenesis. , 1997, Journal of biochemistry.

[9]  F. Silver,et al.  Effects of fibroblasts and basic fibroblast growth factor on facilitation of dermal wound healing by type I collagen matrices. , 1991, Journal of biomedical materials research.

[10]  N. Isshiki,et al.  Influence of glycosaminoglycans on the collagen sponge component of a bilayer artificial skin. , 1990, Biomaterials.

[11]  C. Körber,et al.  Redefining cooling rate in terms of ice front velocity and thermal gradient: first evidence of relevance to freezing injury of lymphocytes. , 1990, Cryobiology.

[12]  F. Silver,et al.  Collagen-based wound dressings: control of the pore structure and morphology. , 1986, Journal of biomedical materials research.

[13]  M. Chvapil.  Considerations on manufacturing principles of a synthetic burn dressing: a review. , 1982, Journal of biomedical materials research.

[14]  I. Yannas,et al.  Wound tissue can utilize a polymeric template to synthesize a functional extension of skin. , 1982, Science.

[15]  N. Dagalakis,et al.  Design of an artificial skin. Part III. Control of pore structure. , 1980, Journal of biomedical materials research.

[16]  M Chvapil,et al.  Collagen sponge: theory and practice of medical applications. , 1977, Journal of biomedical materials research.

[17]  W. Mullins.  Stability of a Planar Interface During Solidification of a Dilute Binary Alloy , 1964 .

[18]  I. Yannas,et al.  Recent advances in tissue synthesis in vivo by use of collagen-glycosaminoglycan copolymers. , 1996, Biomaterials.

[19]  I. Heschel,et al.  Possible Applications of Directional Solidification Techniques in Cyobiology , 1996 .

[20]  D. Williams,et al.  Biocompatibility of tissue analogs , 1985 .

[21]  P. Aubourg.  Interaction of second-phase particles with a crystal growing from the melt. , 1978 .

[22]  B. Chalmers,et al.  A PRISMATIC SUBSTRUCTURE FORMED DURING SOLIDIFICATION OF METALS , 1953 .