Antimicrobial 3D-Printed Bone Scaffolds Based on Whey-Derived Biocarbon/Bioceramic Composites

To address the risk of infection associated with bone grafting, antimicrobial 3D-printed bone scaffolds were fabricated by direct ink writing (DIW) from porous whey-derived carbon combined with hydroxyapatite (HA) and/or bactericidal bioglass (G3). Whey-based pastes enabled homogeneous dispersion and easy extrusion of the inorganic powders. After carbonization, the resulting biocarbon and composite scaffolds exhibited interconnected macroporosity (400–500 μm) suitable for trabecular bone substitution, together with micro- and nanopores that favor vascularization and protein adsorption. All samples showed compressive strengths comparable to those of trabecular bone (6–10 MPa), with the G3-containing composites being the strongest. Bioactivity tests in simulated body fluid (SBF) confirmed hydroxyapatite formation on all scaffolds, including pure biocarbon, with a better response for the G3-containing compositions. Cytotoxicity assays confirmed biocompatibility, whereas the G3-containing scaffolds additionally exhibited clear bactericidal behavior against E. coli and S. epidermidis . These results highlight the incorporation of 20 wt.% G3 as the key element for conferring bactericidal functionality while preserving the structural and biological performance required for bone regeneration.