Diametral tensile strength evaluation of carbonate apatite cement reinforced by genipin cross-linked gelatin

Carbonate apatite (CO3Ap) is one of the most widely studied bioceramic material for its use as bone cement. It is well-known that CO3Ap cement has good osteoconductivity which makes this cement could be replaced by bone. However, the mechanical strength of CO3Ap cement is still low. This low mechanical strength is estimated due to the high porosity and absence of organic components. The aim of this study is to improve the mechanical strength of the CO3Ap cement reinforced by gelatin as an organic component with genipin as a cross-linking agent (Gelapin). The powder phase of vaterite and DCPA at weight ratio 40:60 were mixed with 0.2 mol/L Na2HPO4, 5% (w/v) gelatin, and 20% (v/v) genipin using 0.5 liquid to powder (L/P) ratio. The liquid phase ratios of Na2HPO4 and Gelapin were 50:50, 70:30, and 90:10. For control group, Gelapin was not mixed into the liquid. Diametral tensile strength was improving and statistically significant (p<0.05) on set cement with 50:50 liquid ratio, the average value was 6.02 ± 0.14 MPa whereas the average value of the control group was only 3.10 ± 0.15 MPa. For this instance, gelatin serves a polymer matrix so the carbonate apatite crystallites could be well distributed within it which then gives more flexibility and resistance for the cement. On the other hand, genipin was also successfully cross-linked the gelatin. This study showed that by reinforcing CO3Ap cement using genipin cross-linked gelatin might be a good candidate for a bone substitute material.