Bioactive Glass Surfaces: A Study on Accelerated Reaction Mechanisms

Strategic Insights -

Recent research from Stockholm University's Division Physics Chemical has shed light on the accelerated surface reaction mechanisms of mesoporous bioactive glasses (MBGs). In a study published in the Journal of Physical Chemistry C, P.N. Gunawidjaja and colleagues applied magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy experiments to explore the surface reactions of a MBG when subjected to simulated body fluid (SBF) for variable intervals. The team employed powder X-ray diffraction and P-31 NMR techniques to monitor the formation of an initially amorphous calcium phosphate surface layer and its subsequent crystallization into hydroxycarbonate apatite (HCA). Their findings suggest that the high bioactivity of phosphorus-bearing MBGs stems from an acceleration of their surface reactions due to the presence of amorphous calcium orthophosphate clusters on the MBG pore wall.

Key Takeaways:

  • The study demonstrated the application of MAS NMR spectroscopy experiments to explore the surface reactions of MBGs subjected to SBF for variable intervals.
  • The team employed powder X-ray diffraction and P-31 NMR techniques to monitor the formation of an initially amorphous calcium phosphate surface layer and its subsequent crystallization into HCA.
  • The researchers observed the dissolution of calcium ions and a slightly increased connectivity of silicate ions on the MBG surface over 1 week of SBF exposure using H-1 → Si-29 cross-polarization (CP) NMR.
  • The incorporation of carbonate and sodium ions into the bioactive orthophosphate surface layer was explored using H-1 → C-13 CPMAS and Na-23 NMR, respectively.
  • The study highlighted similarities and distinctions in composition-bioactivity relationships established for traditional melt-prepared bioglasses compared to MBGs.
  • The high bioactivity of phosphorus-bearing MBGs is rationalized to stem from an acceleration of their surface reactions due to the presence of amorphous calcium orthophosphate clusters on the MBG pore wall.

Statistics:

  • 1 week of SBF exposure observed a slightly increased connectivity of silicate ions on the MBG surface using H-1 → Si-29 cross-polarization (CP) NMR.
  • Powder X-ray diffraction and P-31 NMR techniques employed to monitor the formation of an initially amorphous calcium phosphate surface layer and its subsequent crystallization into HCA.
  • 44 pages of the Journal of Physical Chemistry C (Volume 114, Issue 45) dedicated to the study.

Sources:

  • P.N. Gunawidjaja et al. "Biomimetic Apatite Mineralization Mechanisms of Mesoporous Bioactive Glasses as Probed by Multinuclear P-31, Si-29, Na-23 and C-13 Solid-State NMR." Journal of Physical Chemistry C, 2010;114(45):19345-19356.
  • Stockholm University's Division Physics Chemical, Dept. of Materials & Environmental Chemical, Arrhenius Laboratory, SE-10691 Stockholm, Sweden.
  • American Chemical Society, 1155 16th St., NW, Washington, DC 20036, USA.