Developing Porous Ortho- and Pyrophosphate-Containing Glass Microspheres; Structural and Cytocompatibility...

Area of Science:

• Biomaterials Science
• Materials Chemistry
• Regenerative Medicine

Background:

• Phosphate-based glasses (PBGs) mimic bone's inorganic components, offering potential for bone repair.
• PBG formulation can be adjusted to control degradation and ion release for cellular responses like osteogenesis.

Purpose of the Study:

• To formulate novel invert-PBGs with varying phosphate content (30-40 mol%).
• To process these PBGs into highly porous microspheres (PMS) via flame spheroidisation.
• To evaluate the structural, compositional, ion release, and in vitro bioactivity of the PMS for bone regeneration.

Main Methods:

• Formulation of PBGs with varying phosphate content (xP2O5·(56-x)CaO·24MgO·20Na2O).
• Processing into highly porous microspheres (PMS) using flame spheroidisation (~68-75% porosity).
• Analysis via EDX, 31P-MAS NMR, ion release studies, in vitro bioactivity in simulated body fluid (SBF), and cell culture.

Main Results:

• Reduced phosphate content led to significant depolymerisation, increasing orthophosphate (Q0) species (6% to 35%) and decreasing metaphosphate (Q2) species (50% to 0%) in PMS.
• Ion release decreased with lower phosphate content (up to 4x cations, 8x anions).
• Orthophosphate-rich PMS demonstrated favorable in vitro bioactivity, cytocompatibility, and supported cell growth over 7 days.

Conclusions:

• The P30 PMS, with ~65% pyrophosphate and ~35% orthophosphate, exhibited the most favorable properties.
• These highly porous microspheres are highly suitable for bone repair and regeneration, particularly for orthobiologic applications.