Comparison of drying methods in the fabrication of collagen scaffold via indirect rapid prototyping

Porous collagen scaffolds with predefined 3-dimesional (3-D) networks of internal channels are fabricated via an indirect rapid prototyping technique. To obtain the scaffolds, two drying methods, namely critical point drying and freeze-drying were investigated. The latter was found to be a more suitable process as it induced less shrinkage and reproduced the design morphology accurately. The resulting scaffold contained internal hollow channels with porous foam-like structure occupying the surrounding volume. The mean diameter of the pores was 180 +/- 60 microm and the channels diameter obtained was measured as 437 +/- 100 microm. The channels were defined and strengthened by a layer of skin due to the process of freeze-drying. These networks of internal channels serve to enhance the mass transport rate through the scaffold and help to increase the depth of cells penetration in the scaffold.