Structural connectivity and bioactivity in sol-gel silicate glass design.

Area of Science:

• Biomaterials Science
• Materials Chemistry
• Biomineralization

Background:

• Bioactive glasses (BGs) are crucial for bone regeneration, bonding with bone via hydroxycarbonate apatite (HCA) formation.
• BG bioactivity is intrinsically linked to their structural network connectivity.
• Sol-gel synthesis offers control over BG properties, but the impact of synthesis parameters on bioactivity is not fully understood.

Purpose of the Study:

• To investigate the relationship between sol-gel synthesis parameters (pH, water-to-alkoxide ratio [R_w], titanium doping) and the bioactivity of silica-based BGs.
• To elucidate how network connectivity mediates the effects of synthesis parameters on HCA formation.
• To explore the influence of titanium doping on BG structure and bioactivity.

Main Methods:

• Sol-gel synthesis of BGs and titanium-doped BGs (TiBGs) under varying acidic and basic pH conditions and R_w values.
• Assessment of bioactivity through immersion in simulated body fluid for 7 days.
• Analysis of network connectivity and structural changes, including TiO₂ domain formation.

Main Results:

• Increasing R_w generally enhanced HCA formation, particularly in BGs with high network connectivity (base-catalyzed BGs and all TiBGs).
• Acid-catalyzed BGs with lower connectivity showed less response to increased R_w.
• Basic catalysis in TiBGs inhibited crystalline TiO₂ formation, unlike acidic catalysis.

Conclusions:

• Synthesis pH and R_w are critical for tailoring BG bioactivity and network connectivity.
• Titanium doping enhances network connectivity and bioactivity, with synthesis conditions influencing TiO₂ precipitation.
• Findings provide a basis for designing BGs with controlled ion release and specific properties, such as bactericidal effects.