A novel tantalum-containing bioglass. Part I. Structure and solubility

Bioglasses are employed for surgical augmentation in a range of hard tissue applications. Tantalum is a bioactive and biocompatible transition metal that has been used as an orthopedic medical device. It has a range of biological and physical properties that make its incorporation into ionic form into bioactive glass systems promising for various clinical applications. The work herein reports the characterization and properties of novel tantalum-containing glasses. A series of glasses based on the system 48SiO₂-(36-X)ZnO-6CaO-8SrO-2P₂O₅-XTa₂O₅ with X varying from 0 mol% (TA0) to 0.5 mol% (TA2) were synthesized. The addition of small amounts of Ta₂O₅ did not cause crystallization of the glasses but increasing Ta₂O₅ content at the expense of ZnO was found to result in an increased number of bridging oxygens (BOs). This, along with the data recorded by differential thermal analysis (DTA) and magic angle spinning-nuclear magnetic resonance (MAS-NMR), confirms that Ta acts as a glass former in this series. Solubility experiments showed that minor changes in the glass structure caused by Ta incorporation (0.5 mol%) exhibited greater cumulative % weight loss, pH values and cumulative Zn²⁺ and Sr²⁺ ion concentration over a period of 30 days of maturation, when compared to Ta₂O₅-free glasses. The results presented in this article confirm that replacing ZnO with Ta₂O₅ in silicate glasses results in the formation of stronger bonds within the glass network without any adverse effects on the solubility of the glasses prepared from them. - Highlights: • Ta₂O₅ can be incorporated into silicate based ionomer glasses up to 0.5 mol%. • Incorporation resulted in amorphous glasses. • Insertion of TaO units into the silicate network confirms the former role of Ta₂O₅. • The incorporation increased the glass solubility.