In Vitro Characterization of 3D-Printed PLA/CPO Oxygen Releasing Scaffolds: Mechanical and Biological Properties for Bone Tissue Engineering

The addition of oxygen-releasing biomaterials into 3D-printed scaffolds presents a novel approach to enhancing bone scaffolds, yet no in vitro studies have demonstrated the effect of oxygen-generating filaments on scaffold biological and mechanical properties. This study introduces a polylactic acid (PLA)/calcium peroxide (CPO) composite filament, designed for oxygen release, which is a key factor for early-stage bone regeneration. The PLA/CPO composite filament was fabricated via wet-mixing, solvent evaporation, and hot-melt extrusion, followed by fused deposition modeling (FDM) with optimized parameters to achieve high structural fidelity (25% porosity, 0.60mm pore size). In vitro characterization, including mechanical, morphological, and biological assessments, demonstrated that, post-cell culturing, mechanical strength improved, which indicates improved scaffold resilience. The scaffold exhibited gradual oxygen release over a 3-day period, and gene expression analysis confirmed notable upregulation of osteogenic markers RUNX2, SPP1, and SP7 in vitamin D-supplemented conditions. The mechanical strength improved from approximately 2.8 MPa in the control group to 5.0 MPa in scaffolds cultured with osteogenic media. This study provides the first in vitro evidence that oxygen-releasing 3D-printed filaments can improve both mechanical properties and biological response in scaffolds, demonstrating the functional integration of sustained oxygen delivery, enhanced mechanical properties, and increased osteogenic activity in a single 3D-printed scaffold.