Preparation of a calcium carbonate-based bone substitute with cinnamaldehyde crosslinking agent with potential anti-inflammatory properties.

Calcium sulfate (CS), also known as POP (Plaster of Paris) is a self-setting, biocompatible, and osteoconductive biomaterial with a long history for the treatment of skeletal defects. However, CS cements show a too fast resorption rate and are unable to provide a long-term 3D framework during the osteogenesis process. In our previous studies, it was found that the incorporation of CaCO3 and CaCO3 hydrogel provided enhanced mechanical and degradation properties of POP composites. Furthermore, it was also found that the use of cinnamaldehyde to crosslink CaCO3 hydrogel may have some advantages, for example to crosslink the hydrogel and to act as anti-inflammatory control agent. The objective of the current study was to evaluate the effect of adding cinnamaldehyde crosslinked CaCO3 hydrogel into POP on the diametral tensile strength, weight loss, age swelling, degradation, cinnamaldehyde release, and porosity. The following composites were prepared: POP/HCin-025 (25% addition of hydrogel microsphere) and POP/HCin-050 (50% addition of hydrogel microsphere). The composites were assessed on their diametral tensile strength, weight loss of the POP composite, age swelling, degradation of the hydrogel CaCO3 , cinnamaldehyde release, and porosity, as well as XRD-patterns and FT-IR spectra. It was confirmed from the study that incorporation of cinnamaldehyde into CaCO3 hydrogel system significantly increased the mechanical strength of the POP composite. Weight loss, swelling ratio in both acid to neutral pH, and biodegradability of the POP composites were controllable by the addition of cinnamaldehyde-CaCO3 hydrogel. Moreover, the cinnamaldehyde incorporated into the hydrogel was proven to be released in a controlled manner.