Quantitative features of osteo-bioactive Ti surfaces at the atomic/molecular level

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Biomineralization
• Computational Materials Science

Background:

• Osteo-bioactivity of biomaterials is influenced by physicochemical properties, but the structure-activity relationship for titanium (Ti) in bone repair is not fully understood.
• Titanium's surface characteristics, including topography and chemical composition, play a critical role in its integration with bone tissue.
• Quantifying the optimal surface features for enhanced osteogenic activity in titanium is essential for advancing bone repair materials.

Purpose of the Study:

• To quantitatively enhance the osteogenic activity of titanium surfaces using femtosecond laser (FSL) technology.
• To explore the relationship between characteristic Ti surface parameters and osteo-bioactivity by analyzing apatite deposition.
• To investigate the ion aggregation behavior on Ti surfaces with different bioactive sites using molecular dynamics (MD) simulations.

Main Methods:

• Femtosecond laser (FSL) technology was used to create Ti surfaces with gradient changes in bioactive (nucleation) sites.
• Mineralization experiments were conducted to assess apatite deposition ability on etched Ti surfaces.
• Classical molecular dynamics (MD) simulations were employed to study calcium and phosphate ion aggregation on Ti surfaces.

Main Results:

• The type and density of bioactive sites significantly influence apatite deposition on Ti surfaces.
• Titanium dioxide (TiO2) and titanium hydroxide (Ti-OH) were identified as key bioactive sites, with basic Ti-OH being more effective than acidic sites.
• Optimal osteo-bioactivity requires minimum bioactive site densities of 2.33 ± 0.55 nm⁻² for TiO2 and 2.50 ± 0.59 nm⁻² for Ti-OH.

Conclusions:

• The study elucidates the atomic/molecular features of Ti surfaces that promote apatite deposition and enhance bioactivity.
• Establishing minimum densities for TiO2 and Ti-OH bioactive sites provides a quantitative guideline for designing effective titanium-based bone repair materials.
• These findings facilitate the development of advanced titanium materials for accelerated bone regeneration.