Poly(L-lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/hydroxyapatite based composites for bone tissue...

Bone tissue engineering based on injection molded constructs is inherently complex process as the developed material needs to fulfil a whole gamut of criteria to promote cell attachment, proliferation, and differentiation while exhibiting optimum biocompatibility, adequate mechanical stability, and bioresorbability. This study aims to examine the role of Poly (L-Lactic acid) (PLA) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as melt extruded blends with enhanced properties through addition of bioactive hydroxyapatite (Ca₁₀ (PO₄)₆(OH)₂, (HAp)). The fabricated composites were subjected to impact strength evaluation which indicated reduction in mechanical strength with increasing biofiller content (3, 5, 7, and 10 w/w%). 3 wt% PLA/PHBHHx_HAp was identified optimum with an impact strength of (123.8-476.1 J/m). The in vitro bioactivity evaluation in simulated body fluid (SBF) revealed the complete coverage of PLA/PHBHHx_HAp composites by a thick bone-like apatite layer. The in vitro hydrolytic degradation study (after 60days at 37 °C) of composites exhibited mass loss of about 4.1-5.6%, reflecting slow and gradual degradation behaviour under physiological conditions. Considering porosity and surface characteristics, composite composed of higher PHBHHx content demonstrated higher in vitro cytocompatibility, adhesion, and viability (12-16% increase in 24 h) for MG-63 osteoblast while exhibiting induced calcium deposition and mineralized nodules. This study presents PLA/PHBHHx_HAp biocomposites as promising mechanically tuned biomaterials with demonstrated bioactivity potential and cytocompatibility for potential treatment of osseous defects.