PLA/hydroxyapatite composite scaffolds fabricated by digital light processing for bone regeneration

Bone tissue regeneration faces a major challenge: traditional therapies such as autografts and allografts are limited by donor site morbidity, restricted availability, and potential immune rejection. Therefore, there is a pressing need to develop synthetic scaffolds that mimic the extracellular matrix while providing adequate mechanical, morphological, and biological properties to promote osteogenesis and angiogenesis. In this study, polylactic acid/hydroxyapatite (PLA/HAp) scaffolds were designed using Digital Light Processing (DLP) 3D printing technology, strategically integrating HAp nanoparticles (NPs) at concentrations ranging from 0 to 5 wt%. The scaffolds exhibited a biomimetic cylindrical architecture with interconnected square pores of 350 µm and a theoretical porosity of 78% calculated from the CAD models. Finite element analysis (FEM) revealed high structural stability under physiological loads, with maximum displacements of 3.09 × 10⁻² mm and stress levels well below the elastic limit of polylactic acid (PLA). Morphological characterization by scanning electron microscopy (SEM) showed a progressive increase in surface roughness with higher HAp content, without agglomeration, as confirmed by energy dispersive spectroscopy (EDS) mapping. Cell viability studies using 3T3-L1 fibroblasts demonstrated a significant increase in metabolic activity, with the M4 (4%) and M5 (5%) samples reaching viabilities of 79.8% and 86.1%, respectively, classifying them as highly biocompatible according to ISO 10993-5. These results demonstrate that DLP printing enables the synthesis and design of PLA/HAp cellular scaffolds with precise geometry, excellent mechanical performance, and tunable bioactive properties, positioning them as a promising alternative for bone tissue engineering.