Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route

Area of Science:

• Biomaterials Science
• Nanotechnology
• Materials Chemistry

Background:

• Calcium phosphates are key nanobiomaterials for bone repair, signaling, and drug/gene delivery.
• Metastable amorphous calcium phosphate (ACP) shows high reactivity, crucial for bone development, but synthesis control is challenging.
• Controlling ACP's crystalline structure, composition, particle shape, and size is vital for its biomedical applications.

Purpose of the Study:

• To adapt the epoxide route for synthesizing pure and stable amorphous calcium phosphate (ACP) colloids.
• To achieve control over the shape, size, and phase purity of ACP.
• To explore the use of biocompatible green solvents for ACP synthesis.

Main Methods:

• Adapted the epoxide route using biocompatible solvents like ethylene glycol and/or glycerine.
• Utilized solvent mixtures to prevent ACP maturation into crystalline apatites.
• Tuned the fractalization of the internal mesostructure by adjusting solvent composition.

Main Results:

• Successfully synthesized pure and stable amorphous calcium phosphate (ACP) colloids.
• Achieved control over particle size, ranging from 60 nm nanoparticles to >500 nm spheroids.
• Demonstrated tunable fractalization of the internal mesostructure by varying solvent mixtures.
• Avoided the need for capping agents, preserving the natural surface reactivity of ACP.

Conclusions:

• Green solvents offer a novel approach to control crystallinity and particle size in nanomaterial synthesis.
• The developed method provides a synthetic route to stable ACP colloids with tunable properties.
• This advancement facilitates the use of ACP in biomedical applications by overcoming previous synthetic challenges.