Composition and morphology effects on catalase mimetic activity of potential bioactive glasses

Abstract The catalase mimetic activity (CMA) of potential bioactive glasses based on Hench - 45S5 Bioglass® (46.1%SiO2-24.4%Na2O-26.9%CaO-2.6P2O5 mol%, called H), Kokubo bioactive glass (50%SiO2–25%Na2O–25%CaO mol%, called K) and mesoporous bioactive glass (80%SiO2–15%CaO–5%P2O5 mol%, called MBG) modified by the introduction of metal oxide (MO, M = Ti, V, Mn, Fe, Co, Cu, Zr and Ce) was tested in order to verify how their composition, morphology and synthesis procedure influence the ability to inhibit oxidative stress in terms of decomposition of hydrogen peroxide (H2O2), a common reactive oxygen species (ROS). The characterization was achieved on the glasses before and after the soaking in H2O2 in order to obtain information about the kinetic order, the rate and the type of mechanism related to the decomposition H2O2 process. In fact, the H2O2 decomposition can follow a radical mechanism (with the formation of OH● radical) or a peroxide-complex mechanism. Tests in SBF solutions were performed in order to verify the bioactivity in term of hydroxyapatite (HA) formation. The introduction of metal oxide into the glass composition promotes the CMA and the better catalytic activities were gained for the Co-, Mn-, Cu-, Ce- and Fe-containing glasses. All these glasses follow a 1st order kinetics but only in the case of Ce-containing glasses (H_4.0Ce) we observe a peroxide-complex mechanism. The Ce-containing glasses preserve their catalytic activity also coated with alginate and the reduction of glass powder dimension enhances the rate of H2O2 decomposition. Mesoporous glasses with a high specific surface area show a higher H2O2 decomposition rate with respect to that of melt-quenched derived glasses. The introduction of Ce, Cu, V, Ti, Zr and Fe do not modify the bioactivity in terms of HA formation during SBF tests (respect to H bioactive glass) and the alginate coating delay the HA formation without inhibiting its formation. H_5.3Co and H_5.3Mn showed the best catalytic performance (highest k value) but they seem not bioactive until 28 days of SBF soaking. By the data analysis obtained in this manuscript, we can affirm that the Ce-containing glasses are the most promising potential bioactive glasses with antioxidant properties.