Promising investigative study: valorizing sardine scales by-products as eco-friendly carbonated calcium phosphate biomaterials for bone tissue engineering

The present work studied the physicochemical and biological properties of fish scales composed of natural carbonated hydroxyapatite, called SS-CaPx (where x represents sample indexation). Fish scales and mainly European sardine ( Sardina pilchardus) scales were used, their behavior was compared with those of healthy rat bone (HRB) and synthetic hydroxyapatite (HA syn). A simulation of the crystallite size on the X-ray patterns confirmed the nanocrystals present in the natural matrix (SS-CaP1 and HRB) produce broad peaks compared to HA syn. The broad peaks observed in SS-CaP1 are primarily due to simultaneous elastic and inelastic scattering, rather than low crystallinity. The analysis shows that the SS-CaP1 is composed of approximately 10 nm in length and 3 nm in width sized nanocrystal, whereas HA syn is composed of particles of about 34 nm in length and 12 nm in width. Calcium phosphate molar ratio (Ca/P) of SS-CaP1 does not exceed 1.84. Cytotoxicity assay (MTT) shows significant increases in the proliferation and activity of osteoblasts, fibroblasts and mesenchymal stem cells over the chosen sample (SS-CaP1) after 72 hours of culture. These results confirm the biomaterials derived from sardine scales SS-CaPx have biologically the potential for use as bone regenerative materials .