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-2P2 O5 -XTa2 O5 with X varying from 0mol% (TA0) to 0.5mol% (TA2) were synthesized. The addition of small amounts of Ta2 O5 did not cause crystallization of the glasses but increasing Ta2 O5 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 (0.5mol%) exhibited greater cumulative % weight loss, pH values and cumulative Zn2+ and Sr2+ ion concentration over a period of 30days of maturation, when compared to Ta2 O5 -free glasses. The results presented in this article confirm that replacing ZnO with Ta2 O5 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.