Rehydration Effects on Physicochemical Properties of a Collagen-based Graft

OBJECTIVE: This study was undertaken to test how different rehydration times may affect the physicochemical properties of a commercially available (Alloderm^®) collagen-based allograft.

METHODS: A sterile dish with 50-100 mL of warming (37°C) saline solution was prepared, and then samples were aseptically cut and kept submerged into it for 5 min when backing paper separated from the grafts. Subsequently, three other dishes containing 50 mL of the solution were prepared and each one of the materials assigned into three groups according to the rehydration time: G1-10min, G2-20min, and G3-40min. The chemical structure of the different samples was assessed by FTIR spectroscopy, DSC and TGA thermal methods.

RESULTS: FTIR confirmed the protein backbone of the collagen-based graft, since the amides I, II and III band, were found with no significant peak shifting with different rehydration time. DSC thermograms of G1, G2, and G3 showed a visible transition, suggesting the denaturation temperature (T_D). However, a shift in T_D to a higher temperature was observed with G3 sample. The T_D shifting to a higher temperature suggests stronger polymer-water bridge, which in turn should affect the mechanical properties of the graft. DSC result of an as-received sample (no rehydration) revealed the transition in a much lower temperature (67°C). TGA demonstrated for all conditions tested a maximum percentage transitional weight loss around 57°C due to the water removal. A second transition band representing the decomposition stage was noticed with maximum around 280°C, with a higher weight lost for the G3 sample compared to G1 and G2.

CONCLUSION: The current study suggests there are physicochemical changes in the graft after different rehydration times. Further investigation on the mechanical properties should be done to verify the possible effects on the elastic behavior of the sample during its surgical application.

ACKNOWLEDGMENT: We thank Biohorizons (Birmingham-AL-USA) for graft donation.