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 influeuce, 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 mum. The thickness of the sponges prepared during this research was 10 mm, (C) 2001 John Wiley & Sons. Inc.