Direct ink writing of 3D scaffold polymeric-bioceramic from sand lobster shells (Panulirus homarus) waste as a sustainable resouce for enhancing in vitro bioactivity

Allografts and autografts methods for bone fracture healing remain challenging due to infection and disease transmission risk. Bone grafts from calcium-phosphate bioceramics such as hydroxyapatite (HA; (Ca₁₀(PO₄)₆(OH)₂)) are widely applied in clinical use because HA is the largest compound that makes up bone. However, commercial HA has brittle mechanical properties and lacks inorganic minerals in native bone. Apart from that, conventional methods for bone graft preparation, such as porogen leaching, freeze drying, and foaming, produce inhomogeneous scaffold designs. In this study, we successfully fabricated the 3D printing scaffold composite direct ink writing (DIW) from polymer polycaprolactone (PCL) and bioceramic hydroxyapatite from sand lobster shell (SLS; Panulirus homarus) waste (HA-SLS) which can produce precise pore shapes and scaffold designs. Using new biogenic waste sources from sand lobster shells has a natural Mg ion content of 6.93 % in the form of β-tricalcium-magnesium phosphate (β-TCMP), which can increase its bioactivity. 3D PCL/HA-SLS was varied at 0 %, 10 %, 30 %, and 50 %, and then biomineralization in SBF solution and cell responses to rabbit bone marrow stem cells (rBMSCs) were conducted to evaluate the effect of HA-SLS on scaffold bioactivity. The results show that incorporation of HA-SLS into the PCL can release the bioactive ions Ca, P, and Mg, which provide good biological responses to the rabbit bone marrow stem cells (rBMSCs) for cell adhesion, proliferation, and osteogenesis differentiation. A higher concentration of HA-SLS can stimulate osteogenesis differentiation of rBMSCs, which is marked by increased alkaline phosphate activity, alizarin red, and bone-related gene expression compared to pure PCL, which can promote bone regeneration. Polymer-bioceramic composites can also improve their mechanical properties by hindering brittle fracture and increasing the toughness and resistance to fracture in the final compression state, so this strategy can obtain good mechanical properties and bioactivity responses in bone tissue engineering.