Fabrication of a glycerol-citrate polymer coated tricalcium phosphate bone cements: Structural investigation and material properties

Calcium phosphate cements (CPCs) belong to one of the most prominent biomaterials used for filling and regeneration of hard tissues, however poor mechanical and biological properties limit their widespread use in some clinical applications. To solve these problems, a biodegradable glycerol-citrate (G-CA) polyester was synthesized and coated on tricalcium phosphate cement (TCP) powders in amounts up to 10 wt% of the G-CA content using a simple solution infiltration technique in ethanol solution. Chemical and structural analysis of the G-CA elastomer and TCP/G-CA composites were thoroughly analyzed with chromatographic techniques, solid-state nuclear magnetic resonance (ssNMR), differential scanning calorimetry and thermogravimetry (DSC/TG), X-ray diffraction (XRD), Fourier-Transform Infrared spectroscopy (FTIR) and field emission scanning electron microscopy (SEM). The results demonstrated that the incorporation of 2.5 and 5 wt% of G-CA into TCP cement led to a significant increase of mechanical strength of the cements due to the formation of thin and homogeneous elastomer coating on cement particles, reinforcing the microstructure through hydrogen bonds between residual COOH groups of polymer and surface phosphate groups of the cement matrix. Additional in vitro testing of extracts cytotoxicity revealed a high proliferation of osteoblasts in all composites, demonstrating a promising application potential in regenerative medicine.