In vitro differences of hydroxyapatite from different resources in simulated body fluid

Area of Science:

• Biomaterials Science
• Materials Chemistry
• Biomineralization

Background:

• Hydroxyapatite (HA) is vital for orthopedic and dental implants.
• Synthetic HA stability in ionic environments remains a concern.
• Investigating HA from diverse sources is key to improving implant performance.

Purpose of the Study:

• To evaluate the in vitro stability of HA from commercial, chemical, and natural limestone sources.
• To analyze the impact of different HA sources on simulated body fluid (SBF) chemistry.
• To characterize the apatite layer formed on HA surfaces in SBF.

Main Methods:

• Three HA types (HAC, HAS, HAK) were immersed in SBF for 31 days.
• SBF pH, Calcium (Ca), and Phosphate (P) ion concentrations were monitored.
• X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyzed HA reactions and surface changes.

Main Results:

• HAK exhibited the smallest crystallite size, affecting SBF pH.
• Ca and P ion concentrations decreased over time, with varying rates for each HA type.
• Apatite growth occurred on all HA surfaces within 3 days, showing distinct morphologies.

Conclusions:

• HA source significantly influences its behavior in SBF.
• Natural limestone-derived HA (HAK) presents unique characteristics.
• Further research is needed to understand apatite crystal differences and cellular effects.