Mechanochemical synthesis and cold sintering of mussel shell-derived hydroxyapatite nano-powders for bone tissue regeneration

According to the circular economy principles, processing routes aiming at reducing the natural resources con-sumption and the energy demand can be addressed as 'green'. In this framework, mussel shells, a natural feedstock of calcium carbonate, were successfully transformed into nano-crystalline hydroxyapatite by mecha-nochemical synthesis at room temperature after mixing with a phosphoric acid solution. The as-synthesized powder was then consolidated up to 82 % relative density by cold sintering (600 MPa, 200 degrees C). The materials were fully investigated by physical, chemical and thermal characterization techniques. Cold-sintered samples were also subjected to biaxial flexural strength test, showing a flexural resistance of 23 MPa. Cell viability assessment revealed that cold sintered hydroxyapatite derived from mussel shells promotes faster adhesion and spreading of human bone marrow-derived mesenchymal stem cells, in comparison to a commercial hydroxy-apatite sintered at 1050 degrees C. Therefore, cold-sintered mussel shells-derived hydroxyapatite can be a promising future candidate scaffold for bone tissue regeneration.

Automated summary

According to the principles of circular economy, processing routes that aim to reduce natural resource consumption and energy demand can be considered as 'green'. In this study, mussel shells were successfully transformed into nano-crystalline hydroxyapatite through mechanochemical synthesis at room temperature. The resulting powder was then consolidated through cold sintering, resulting in high relative density and flexural strength. Cell viability assessment showed that the cold-sintered hydroxyapatite derived from mussel shells promoted faster adhesion and spreading of human bone marrow-derived mesenchymal stem cells compared to a commercially sintered hydroxyapatite. Therefore, it has the potential to be a promising scaffold material for bone tissue regeneration.