Development of PLA/PVA composite scaffolds reinforced with hydroxyapatite for bone tissue engineering applications

Bone tissue, the second most frequently replaced tissue in the human body, requires over four million surgeries annually, often with considerable risk, driving the advancement of tissue engineering as a promising alternative to autologous grafts through the development of multifunctional, biocompatible, and bioactive 3D scaffolds that promote osteoconductivity and mimic the native bone environment. In this study, poly(lactic acid) (PLA), a bio-based, mechanically strong yet hydrophobic polymer, was blended with poly(vinyl alcohol) (PVA), a biodegradable, hydrophilic polymer with lower mechanical strength, to fabricate composite filaments. Six PLA/PVA ratios were evaluated. Scaffolds were fabricated via Fused Deposition Modeling (FDM) and subsequently freeze-dried to enhance porosity and water absorption. To improve bioactivity, scaffolds were surface-coated with hydroxyapatite (HA), a naturally occurring bone mineral synthesized via a hydrothermal method. Scaffolds were thoroughly characterized through FTIR and XRD (physicochemical analysis), SEM and EDS (morphological analysis), and micro-CT. Their performance under simulated physiological conditions was examined through water absorption and mechanical testing. The freeze-dried scaffold with a 25:75 PLA/PVA ratio showed the highest water absorption capacity of 277.7% after 210 minutes, compared to its non-freeze-dried counterpart, which reached 270.1% in 75 minutes. Compression testing further demonstrated that scaffolds possessed a Young’s modulus of 12.284 MPa, closely approximating that of natural cancellous bone. The synthesized HA for coating had a meso-nanometric average particle size of 32.5 nm and a uniform spherical morphology. Its successful incorporation into the scaffold was confirmed by FTIR, while uniform dispersion across the scaffold surface was verified by SEM imaging. These findings indicate that the freeze-dried PLA/PVA (25:75) scaffold reinforced with hydroxyapatite presents an effective and sustainable approach for bone tissue engineering. Its combination of mechanical strength, high water absorption, and bioactive surface properties makes it a strong candidate for future bone regeneration applications.