Nanostructured TiO₂ Surface Enriched with CeO₂ over Ti Metal for Enhanced Cytocompatibility and Osseointegration for...

Area of Science:

• Materials Science
• Biomedical Engineering
• Surface Chemistry

Background:

• Titanium (Ti) implants are widely used in orthopedics but are susceptible to infection and may have limited osseointegration.
• Surface modification of Ti can enhance its biological and antimicrobial properties.
• Cerium (Ce) incorporation offers potential benefits due to its redox properties and known bioactivity.

Purpose of the Study:

• To analyze the thermal regulation of the cerium (Ce) oxidation state (Ce3+/Ce4+) on nanonetwork titania layers over titanium (Ti) surfaces.
• To evaluate the impact of sequential heat treatments on surface characteristics and biological performance.
• To investigate the potential of Ce-functionalized Ti surfaces for orthopedic applications, focusing on antibacterial activity, cell compatibility, and osseointegration.

Main Methods:

• Alkali-mediated surface modification of Ti followed by sequential heat treatments (200-800 °C).
• Characterization of surface properties including morphology, phase, roughness, and hardness.
• Assessment of antibacterial activity against Staphylococcus aureus and Escherichia coli.
• Evaluation of MG-63 cell compatibility (adhesion, cytotoxicity, mitochondrial potential, ECM mineralization).
• In vivo studies using rat models with additively manufactured Ti scaffolds to assess osseointegration via histology and micro-CT.
• Analysis of osteogenic gene expression (ALP, OCN, OPN, OSX, RUNX2) using RT-PCR.

Main Results:

• Heat treatment up to 600 °C increased Ce4+ (CeO2) content and formed a rutile TiO2 network.
• Treatment at 800 °C resulted in increased Ce3+ (Ce2O3) content, improved nanohardness, and altered surface morphology.
• The coexistence of Ce4+/Ce3+ on porous titania layers enhanced antibacterial activity.
• The sample heat-treated at 600 °C (high Ce4+/Ce3+ ratio) showed improved MG-63 cell compatibility and higher ECM mineralization.
• In vivo studies demonstrated significantly enhanced osseointegration potential with Ce-functionalized scaffolds (600 °C treatment).
• Upregulation of key osteogenic marker genes confirmed the osteogenic potential of ceria surface functionalization.

Conclusions:

• Ce-incorporated nanostructured titania layers on Ti, particularly with a high Ce4+/Ce3+ ratio achieved via 600 °C heat treatment, exhibit promising antibacterial properties.
• This surface modification enhances cell compatibility and promotes osseointegration, reducing infection risk and improving implant performance in orthopedic applications.
• The study validates ceria functionalization as a viable strategy for developing next-generation orthopedic implants.