Use of natural coralline biomaterials as reinforcing and gas-forming agent for developing novel hybrid biomatrices: microarchitectural and mechanical studies.

This paper describes the first attempt in fabrication of three-dimensional macroporous composites of chitosan and natural coralline material with pore sizes of 300-400 microm, exceeding the upper pore size limit of 250 microm obtained with freeze-dried chitosan-based scaffolds. Natural coral particulates of less than 20 microm, which is mainly composed of calcium carbonate (CaCO3), was simultaneously used as reinforcing phase and gas-forming agent to obtain a structure with large pores and improved mechanical and biological properties. The reaction between the coralline material and the acidic chitosan polymer solvent, which produced carbon dioxide, was rapidly stopped by the subsequent thermally induced phase separation technique, leaving coralline particulates in the polymeric structure.

Responses of mesenchymal stem cell to chitosan-coralline composites microstructured using coralline as gas forming agent.

Macroporous composites made of coralline:chitosan with new microstructural features were studied for their scaffolding potential in in vitro bone regeneration. By using different ratios of natural coralline powder, as in situ gas forming agent and reinforcing phase, followed by freeze-drying, scaffolds with controlled porosity and pore structure were prepared and cultured with mesenchymal stem cells (MSCs). Their supportive activity of cellular attachment, proliferation and differentiation were assessed through cell morphology studies, DNA content, alkaline phosphatase (ALP) activity and osteocalcin (OC) release.