Abstract
The content of this thesis concerns the production and characterization of phosphate-based glasses in the P2O5-CaO-Na2O system for biomedical applications via new synthetic routes, alternatives to the melt-quench method.
The coacervate method, a room-temperature, scalable and greener method to produce phosphate-based glasses, was used to produce phosphate-based glasses doped with therapeutic ions (Ag+, Cu2+ and Zn2+). The structure of these coacervate glasses was probed by the use of rheology, X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, Raman spectroscopy, 31P nuclear magnetic resonance spectroscopy, 31P and 23Na magic angle spinning nuclear magnetic resonance spectroscopy as well as using synchrotron techniques, X-ray absorption spectroscopy and high-energy X-ray diffraction. This structural investigation confirms that glasses made via the coacervation process have similar atomic structures to those produced via the melt-quench method.
The antibacterial and dissolution properties of silver-doped coacervate glasses were also explored, with these glasses expressing antimicrobial properties. Dissolution of these silver-doped coacervate glasses is shown to occur rapidly and potential methods for retarding the dissolution rate are discussed.
Coacervation has also shown itself to be versatile for the production of phosphate-based glass fibres which can be again doped with therapeutic ions (Ag+, Cu2+, Zn2+ and Sr2+). The atomic environments of these ions were explored via X-ray absorption spectroscopy and were shown to be similar to those of bulk glasses.
The sol-gel method provides a synthetic route to produce multifunctional glasses with a variety of morphologies. Investigation was undertaken into the synthesis of mesoporous phosphate-based glasses via a soft-template sol-gel route and the incorporation of therapeutic ions (Ag+, Sr2+ and Ga3+) was explored. The atomic environments of these therapeutic ions were probed via X-ray absorption spectroscopy. Porosity of these glasses was found to be highly dependent on the synthetic parameters, such as water:ethanol ratios. The synthetic method developed here was also shown to be tolerant to the incorporation of therapeutic ions, with atomic environments similar to those observed in glasses produced via other methods.
In the production of glasses for biomedical applications, both the coacervation and sol-gel methods have been proven to be facile alternatives to the melt-quench method.