Dissolution,bioactivity behavior,and cytotoxicity of rare earth-containing bioactive glasses (RE = Gd,Yb)

Rare earth-containing bioactive glasses (RE-BGs) have been poorly explored in the biomaterials field, although RE has optical, nuclear, and magnetic properties that could be used in different biomedical applications. In order to verify whether these glasses can be promising as biomaterials, we studied the dissolution, bioactivity, and cytotoxicity of RE-BGs based on the SiO₂–Na₂O–CaO–P₂O₅–RE₂O₃ (RE = Gd, Yb) system. The glasses were obtained by melting-quenching and their particle size was determined by laser diffraction. Their dissolution behavior was studied in Tris-HCl, while bioactivity was performed in simulated body fluid solution under physiological conditions during several periods. The cytotoxicity test was performed using glass-derived conditioned medium and mesenchymal stem cell derived from deciduous teeth. The dissolution results showed that the glasses dissolved under two different kinetics, which are lower for rare earth-containing glasses, due to the more covalent character of Si–O–RE bonds. The bioactivity results evidenced that all glasses showed bioactivity after 24 hours. However, gadolinium and ytterbium promoted a more calcium phosphate deposition, which contrasts with the slower dissolution kinetics of rare earth-containing glasses. All the glasses were considered biocompatible, showing cell viability higher than 80%. The overall results showed that RE-BGs are promising materials for applications that require bioactivity and/or biocompatibility.