Synthetic amorphous calcium phosphates (ACPs): preparation, structure, properties, and biomedical applications

Area of Science:

• Biomaterials Science
• Biomineralization
• Materials Chemistry

Background:

• Amorphous calcium phosphates (ACPs) are metastable, glass-like materials lacking long-range atomic order.
• Naturally occurring ACPs are found in biological tissues and milk, while synthetic ACPs are produced via wet-chemical precipitation.
• ACPs are thermodynamically unstable and tend to convert to crystalline apatitic structures unless stabilized.

Purpose of the Study:

• To review the current knowledge on synthetic amorphous calcium phosphates (ACPs).
• To summarize their occurrence, structural design, chemical composition, preparation, properties, and biomedical applications.
• To highlight the biological relevance and potential of ACPs in biomineralization and regenerative medicine.

Main Methods:

• Literature review of synthetic amorphous calcium phosphates (ACPs).
• Analysis of synthesis methods, focusing on wet-chemical precipitation.
• Examination of ACPs' properties, including metastability and transformation pathways.

Main Results:

• Synthetic ACPs are the initial solid phases in precipitation reactions involving Ca2+ and PO43- ions.
• The inherent metastability of ACPs is critical for biological processes like matrix vesicle biomineralization.
• ACPs demonstrate significant potential as biomaterials for bone grafts and dental restorations.

Conclusions:

• Amorphous calcium phosphates are vital intermediates in biomineralization and possess considerable potential for biomedical applications.
• Understanding the synthesis and properties of ACPs is crucial for their effective use in regenerative medicine.
• Further research into stabilizing ACPs could enhance their utility in bone and dental tissue engineering.