Titanium Dioxide-Coated 3D-Printed Scaffolds for Bone Tissue Engineering

Objectives: The aim of this study was to fabricate 3D-printed polycaprolactone scaffolds coated with titanium dioxide nanoparticles (TiO₂) to increase the surface roughness, mechanical properties, biocompatibility, cell proliferation and adhesion to the scaffolds.
Methods: Polycaprolactone scaffolds were 3D-printed using a previously reported technique, and the surface was coated with a slurry of TiO₂ nanoparticles (70 % wt.). The slurry was mixed using a homogenizer and coated on the surface of scaffolds using hydraulic pressure by loading the slurry and the scaffolds in a cylindrical syringe. The loaded syringe was kept in an oven at 65 ^oC for 90 minutes. The mechanical properties, physical characterizations, biocompatibility, cell proliferation and differentiation of the scaffolds were fully investigated.
Results: The results indicated that coating the surface of the scaffolds using TiO₂ nanoparticles enhanced the mechanical properties. The morphology of the scaffolds and surface characteristics showed that the TiO₂ coated scaffolds possessed more roughness for cell adhesion compared to the uncoated scaffolds. The mechanical properties also revealed high values of modulus for the coated scaffolds in the range of the cancellous bone. The viability of osteoblast culture was evaluated using Presto blue assay to confirm higher proliferation of coated scaffolds compared to the control group at days 7, 14, and 21 of culture. The alkaline phosphate (ALP) assay also showed that the ALP activity was doubled in the coated scaffolds. The cell culture results imply a higher osteogenic differentiation capacity for the coated scaffolds via TiO₂ nanoparticles.
Conclusions: The results indicated that using TiO₂ nanoparticles for coating the surface of scaffolds significantly increases the mechanical strength of scaffolds. Based on the biocompatibility analyses, the TiO₂ coated scaffolds have the potential to be a promising scaffolds for bone tissue engineering applications.