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

Because of many suitable properties, collagen sponges are used as an acellu lar implant or a biomaterial in the field of tissue engineering. Generally, the inner three-dimensional structure of the sponges influences the behavi or of cells. To investigate this influeuce, it is necessary to develop a pr ocess to produce sponges with a defined, adjustable, and homogeneous pore s tructure, Collagen sponges can be produced by freeze-drying of collagen sus pensions. The pore structure of the freeze-dried sponges mirrors the ice-cr ystal morphology after freezing. In industrial production, the collagen sus pensions are solidified under time- and space-dependent freezing conditions , resulting in an inhomogeneous pore structure. In this investigation, unid irectional solidification was applied during the freezing process to produc e collagen sponges with a homogeneous pore structure. Using this technique the entire sample can be solidified under thermally constant freezing condi tions, The ice-crystal morphology and size can be adjusted by varying the s olute concentration in the collagen suspension, Collagen sponges with a ver y uniform and defined pore structure can be produced. Furthermore, the pore size can be adjusted between 20-40 mum. The thickness of the sponges prepa red during this research was 10 mm, (C) 2001 John Wiley & Sons. Inc.