3D-Printed Alumina-Zirconia Scaffolds via PEG-Laponite® for Bone Regeneration

Due to their unique structural and chemical properties, ceramic scaffolds are vital for various high-performance functional applications, with bone tissue engineering being a highly relevant research field. In this context, the present study aimed to fabricate and characterize Al₂O₃-based scaffolds containing 5 vol.% of nanometric zirconia inclusions, formulated with PEG–Laponite® using the direct ink writing (DIW) technique. The influence of ceramic solid loading (40, 50, and 60 vol.%) and different extrusion nozzle inner diameters on the rheological behavior, extrudability, printing fidelity, and structural characteristics of the resulting scaffolds was investigated. The formulations exhibited favorable rheological performance, with stable viscosity and good shear recovery, ensuring extrudability and shape retention during printing. The 0.51 ± 0.03 mm nozzle was most effective for the 60 vol.% formulation, achieving high-resolution filaments and pores essential for mimicking bone microarchitecture. The ceramic loading significantly affected the microstructure, shrinkage, and mechanical strength, with 60 vol.% leading to higher densification and compressive strength. The hierarchical porous architecture, consisting of well-defined macropores and interconnected micropores, was confirmed by micro-computed tomography. Furthermore, biological assays with Saos-2 cells demonstrated high cell viability and strong adhesion on the 60 vol.% scaffolds, confirming their excellent biocompatibility and potential suitability for bone tissue engineering applications.