Post Processing and Biological Evaluation of the Titanium Scaffolds for Bone Tissue Engineering.

Area of Science:

• Biomaterials Engineering
• Additive Manufacturing
• Tissue Engineering

Background:

• Bone defects from surgery or trauma require advanced solutions.
• Custom-made scaffolds from metallic powders via additive manufacturing (AM) offer a promising alternative.
• Post-processing chemical treatments are essential to remove unfused particles and optimize scaffold properties.

Purpose of the Study:

• To investigate the impact of chemical polishing using diverse acid baths on the morphology, porosity, and mechanical characteristics of novel titanium scaffolds.
• To determine the optimal chemical treatment for different scaffold porosities.
• To evaluate the influence of scaffold pore size on human mesenchymal stem cell behavior.

Main Methods:

• Scaffolds with varying pore sizes (200 µm, 500 µm, and combined) were designed using Magics software and fabricated from commercially pure titanium (CP Ti) via selective laser melting (SLM).
• Chemical polishing was performed using various hydrofluoric (HF) and nitric acid (HF-HNO₃) solutions.
• Scaffold morphology, pore/strut size, and surface uniformity were analyzed using scanning electron microscopy (SEM) and micro-computed tomography (µ-CT).
• Mechanical properties (Young's modulus) and in vitro cell performance (retention, proliferation, differentiation) with human mesenchymal stem cells were assessed.

Main Results:

• Specific acid baths were identified for uniform surface cleaning based on mass loss and SEM observations.
• Chemically polished scaffolds exhibited a Young's modulus comparable to compact bone.
• Smaller pore sizes (200 µm) resulted in higher cell retention and influenced subsequent cell growth.
• In vitro cell performance was demonstrably controllable by adjusting scaffold pore size.

Conclusions:

• Chemical polishing is a critical post-processing step for AM titanium bone scaffolds, significantly influencing their properties.
• Scaffold pore size is a key parameter for controlling cell interaction and in vitro performance.
• Optimized AM scaffolds with tailored porosity show potential for enhanced bone regeneration applications.