Biogenic hydroxyapatite derived from Polymesoda erosa shells tunes structure–property–performance in 3D-printed PLA/PCL scaffolds for bone tissue engineering

Three-dimensional (3D)-printed polymer–ceramic scaffolds are promising for bone tissue engineering, but balancing stiffness, compressive integrity, degradation, and bioactivity remains challenging. This study investigated Polymesoda erosa -derived biogenic hydroxyapatite (HA) as a sustainable calcium phosphate filler for fused deposition modeling of PLA/PCL scaffolds. PLA/PCL/HA filaments and scaffolds containing 0, 40, 45, and 50 wt% HA were fabricated and characterized using SEM–EDX, elemental mapping, DSC, XRD, FTIR, compression testing, PBS degradation, and simulated body fluid (SBF) biomineralization. SEM–EDX confirmed Ca–P distribution in HA-containing filaments and scaffolds, while XRD and FTIR verified HA retention in the printed scaffolds. HA loading increased scaffold crystallinity, surface roughness, porosity, and Ca–P exposure. The elastic modulus increased from 142.11 MPa for PLA/PCL to 368.73 MPa for PLA/PCL/50HA, confirming HA-induced stiffening. However, compressive strength decreased markedly at 50 wt% HA, from 33.42 to 19.90 MPa, due to filler agglomeration, pore irregularity, and stress concentration. Degradation in PBS at stable pH 7 increased with HA loading, with 42-day weight loss rising from 1.63% for PLA/PCL to 8.50% for PLA/PCL/50HA. SBF immersion produced Ca-rich, non-stoichiometric apatite-like deposits, indicating enhanced mineralization. PLA/PCL/45HA provided the best balance between stiffness, compressive integrity, degradation, and mineral deposition. These findings demonstrate the potential of Polymesoda erosa -derived HA for the development of sustainable, bioactive 3D-printed bone scaffolds.