Physicomechanical Performance of a Keratin Fibre and HAp/Sr-Reinforced PCL/PLA Composite Scaffold for Trabecular Bone Repair

Synthetic polymers like polycaprolactone (PCL) and polylactic acid (PLA) are utilised for bone implants due to their controlled degradation profiles and biocompatibility. However, they lack the combined mechanical strength, biodegradability and bioactivity needed for effective bone repair. Hence, this study aims to reinforce the PCL/PLA biopolymer with hydroxyapatite-strontium (HAp/Sr) and keratin fibre. The hydroxyapatite was extracted from animal bone and further reinforced with strontium to improve its bioactive property, while the keratin fibre was obtained from chicken feathers through alkaline hydrolysis. The materials (i.e., PCL, PLA, HAp/Sr and keratin fibre) used in this study were characterised using X-ray diffraction (XRD). Using different concentrations of the materials, the biopolymer scaffold was developed using the solvent casting technique. The mechanical (i.e., hardness and fracture toughness) and physical (i.e., density and porosity) properties of the developed biopolymer scaffold were determined. Three biocomposites (BP₁, BP₂ and BP₃) were fabricated and compared with an unreinforced PCL/PLA sample. XRD analysis revealed semicrystalline PCL, amorphous PLA, characteristic hexagonal HAp peaks, and β-sheet structures in keratin materials. Compared to the PCL/PLA, all reinforced biocomposites demonstrated substantial improvements in porosity, hardness and fracture toughness. The results revealed that reinforcement significantly modified the composite properties. BP₃ exhibited the highest hardness (61.30 Hv) and fracture toughness (1.67 MPa·m^1/2), indicating superior resistance to indentation and crack propagation. BP2 had the highest density (0.249 g/cm³) and porosity (58.86%), suggesting enhanced structural architecture for potential tissue ingrowth. Overall, BP₃ had the most balanced combination of physical and mechanical properties, making the sample the optimal mix for bone tissue engineering, where both biological performance and mechanical integrity are required.