The effect of composition on structural, thermal, redox and bioactive properties of Ce-containing glasses. (5th May 2016)

• Record Type: Journal Article
• Authors: Nicolini, Valentina; Varini, Elena; Malavasi, Gianluca; Menabue, Ledi; Menziani, Maria Cristina; Lusvardi, Gigliola; Pedone, Alfonso; Benedetti, Francesco; Luches, Paola
• Is Part Of: Materials & design. Volume 97(2016)
• Page Start: 73
• Page End: 85
• Publication Date: 2016-05-05
• Subjects: Bioactive glasses -- Cerium -- Catalase mimetic activity -- Bioactivity -- SEM-EDS -- XPS -- Molecular dynamics simulations; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.02.056
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The effect of phosphate on the ability of Ce-containing bioactive glasses to inhibit oxidative stress was studied on compositions based on Hench (46.2%SiO2 24.3%Na2 O26.9%CaO2.6P2 O5, mol%) and Kokubo (50.0%SiO2 25.0%Na2 O25.0%CaO) glasses. In particular, the reduction of catalase mimetic activity of Ce-containing glasses due to the presence: i) of P2 O5 in the glass compositions, and ii) of phosphate groups in the solution employed for catalase mimetic activity tests was explained and rationalized by combining SEM, XPS, XRD, DTA, FT-IR and UV–vis experiments with Molecular Dynamics simulations. The results suggest that the Ce ions play a different structural role in the two series of glasses. In particular, in phosphate free glasses Ce is coordinated by non-bridging oxygens (NBOs) originated from the disruption of the silicate network, whereas in phosphate containing glasses the NBOs around Ce ions belong to orthophosphate groups. The latter groups stabilize the Ce 3+ species subtracting them from the interconversion process between Ce 3+ and Ce 4+, which is of fundamental importance for the exhibition of the catalase mimetic activity. Graphical abstract: Highlights: Different structural roles of the Ce ions in the two series of glasses (with or without phosphate) are found. The structural roles of the Ce ions in the glasses are correlated with bioactivity and catalase mimetic activity. The study allows the design of glass compositions with improved desired properties. Phosphate groups decrease the catalase mimetic activity of the glasses studied.