Strontium/magnesium-doped coralline hydroxyapatite for bone regeneration

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Materials Chemistry

Background:

• Coral-derived hydroxyapatite (CHA) is promising for bone regeneration due to its structure.
• Limitations of CHA include mismatched degradation rates and lack of osteoinductivity.
• Physicochemical and osteogenic mechanisms of doped CHA remain underexplored.

Purpose of the Study:

• To synthesize and characterize strontium-doped (Sr-CHA), magnesium-doped (Mg-CHA), and co-doped (Sr-Mg-CHA) coralline hydroxyapatite.
• To investigate the osteogenic mechanisms and in vitro/in vivo performance of these doped materials.
• To compare their properties against native coral and a commercial bone graft substitute (Bio-Oss®).

Main Methods:

• Hydrothermal synthesis of CHA doped with Sr, Mg, or Sr-Mg, preserving calcium carbonate core.
• Characterization of physicochemical properties including morphology, surface area, and pore volume.
• In vitro assessment of biocompatibility and osteogenic gene/protein expression (ALP, Runx2, COL I, OCN, OPN).
• In vivo evaluation of osteogenesis compared to coral and Bio-Oss®.

Main Results:

• Sr-CHA exhibited optimal nanorod morphology and outperformed Mg-CHA and Sr-Mg-CHA in doping efficiency.
• Doped CHAs showed significantly higher specific surface area and pore volume than native coral.
• All doped CHAs demonstrated enhanced biocompatibility and osteogenic marker expression in vitro.
• Sr-CHA, Mg-CHA, and Sr-Mg-CHA showed improved in vivo osteogenesis compared to coral and Bio-Oss®.
• Sr-CHA demonstrated the best overall performance with tunable Sr2+ release and degradation rates.

Conclusions:

• Doping CHA with Sr and Mg enhances its properties for bone regeneration.
• Sr-CHA shows superior osteogenic potential and tunable characteristics, making it a promising candidate for bone tissue engineering.
• This research provides new insights into doped CHA materials for overcoming limitations in current bone repair strategies.