Amorphous calcium phosphate phase-mediated crystal nucleation kinetics and pathway

Area of Science:

• Biomineralization
• Materials Science
• Crystallization

Background:

• Solution nucleation models are standard for biomineralization kinetics.
• Amorphous calcium phosphate (ACP)-mediated hydroxyapatite (HAP) nucleation deviates from expected linear relationships.

Purpose of the Study:

• To investigate the nucleation mechanism of HAP from ACP in simulated body fluids (SBF).
• To elucidate the role of polymers in ACP-mediated HAP formation.
• To challenge existing solution nucleation models with a heterogeneous nucleation theory.

Main Methods:

• Experimental investigation of HAP nucleation kinetics in SBF.
• Application of developed heterogeneous nucleation theory.
• Analysis of polymer influence (embedded vs. adsorbed) on ACP precursor phase.

Main Results:

• HAP nucleation from ACP follows a heterogeneous pathway at the ACP-solution interface via polymorph transformation.
• Polymers embedded within ACP do not affect HAP nucleation kinetics.
• Polymers adsorbed onto the ACP surface inhibit HAP nucleation.

Conclusions:

• The study confirms a heterogeneous nucleation pathway for HAP on the ACP precursor phase.
• Findings provide a deeper understanding of HAP formation mechanisms in ACP-mediated crystallization.
• The developed heterogeneous nucleation model offers a more accurate explanation for observed kinetics.