Surface properties of calcium phosphate particles for self setting bone cements

Area of Science:

• Biomaterials Science
• Materials Chemistry
• Surface Science

Background:

• Calcium phosphate cements (CPC) are essential biomaterials with particle sizes typically ranging from 1-20 micrometers.
• Surface properties, including zeta potential and adsorption, significantly influence CPC manufacturing and application due to small particle sizes.

Purpose of the Study:

• To investigate the zeta potential of various calcium phosphates (dicalcium phosphate anhydride, tetracalcium phosphate, hydroxyapatite) in different media.
• To assess the impact of suspension media, pH, and sodium phosphate addition on zeta potential and particle stabilization.
• To examine the interaction of calcium phosphates with antibiotics and its effect on surface charge and cement properties.

Main Methods:

• Zeta potential measurements of dicalcium phosphate anhydride (DPCA), tetracalcium phosphate (TTCP), and hydroxyapatite.
• Experiments conducted in various organic/aqueous media across different pH values.
• Analysis of particle interactions with antibiotics and their influence on surface charge.

Main Results:

• Zeta potential showed a strong dependency on the suspension medium and milling properties.
• Sodium phosphate addition led to pH-dependent particle stabilization, increasing zeta potential from -15 to -18 mV in water and -35 to -45 mV in 0.05 mol/l sodium phosphate solution.
• Antibiotic interactions caused significant changes in surface charge, affecting rheology, morphology, setting time, and mechanical strength of the CPC.

Conclusions:

• Zeta potential is a critical parameter for understanding and controlling calcium phosphate cement behavior.
• Suspension media composition and pH play a vital role in particle stabilization.
• Antibiotic incorporation can detrimentally impact CPC performance, necessitating careful consideration during formulation.