Effect of volume fraction of solids on the compressive stress-strain behavior of collagen-glycosaminoglycan scaffolds

Abstract

This thesis aims to examine the effect of volume fraction of solids in collagen-glycosaminoglycan (GAG) scaffolds on the compressive-strain behavior of the structure and compare these results to the open-cell foam model. Collagen-GAG (CG) scaffolds have been used for regenerating skin, conjunctiva, and peripheral nerves with varying levels of success. In these uses, the temporary scaffolds are often deployed with a non-degradable support structure such as a waterproof film or a silicone neural tube which are removed after healing is complete if it is outside the body (for skin regeneration) or are expected to remain permanently in the body (for nerve regeneration). Unfortunately, leaving non-degradable implants in the body could provoke immune responses. At the same time, to remove supports that have been implanted in the body after healing has been completed would result in more injury to the site and other medical complications. For a truly temporary implant, the scaffold must in its entirety be degradable. Thus, the bulk mechanical properties of the scaffold are important to study. Previous research has concentrated on the effects of cells on the scaffolds on a microlevel. However, the scaffold must also be able to bear mechanical stress from surrounding tissues to keep the wound open and provide mechanical support for the body, if, for example, collagen or bone is being regenerated. Here, the bulk mechanical properties of the scaffold are tested under uniaxial, unconfined compression. The Young's modulus and critical stress are calculated from the experimental data and compared to the values predicted by the open-celled foam model. There is very good agreement between the low density scaffolds, with variability in the results increasing with increasing density and with hydration of the specimens. Further research should focus on the

(cont.) However, the scaffold must also be able to bear mechanical stress from surrounding tissues to keep the wound open and provide mechanical support for the body, if, for example, collagen or bone is being regenerated. Here, the bulk mechanical properties of the scaffold are tested under uniaxial, unconfined compression. The Young's modulus and critical stress are calculated from the experimental data and compared to the values predicted by the open-celled foam model. There is very good agreement between the low density scaffolds, with variability in the results increasing with increasing density and with hydration of the specimens. Further research should focus on the origins and the effects of heterogeneities observed in the scaffold structures on the mechanical behavior.