title: Evidence of catalase mimetic activity in Ce(3+)/Ce(4+) doped bioactive glasses.
abstract: The ability of Ce-containing bioactive glasses to inhibit oxidative stress in terms of reduction of hydrogen peroxide, by mimicking the catalase enzyme activity is demonstrated here for the first time. The antioxidant properties of three bioactive glasses containing an increasing amount of CeO2 have been evaluated by following the degradation of hydrogen peroxide with time after immersion in H2O2 aqueous solutions with different concentration. XPS and UV-vis measurements allowed us to determine the Ce(3+)/Ce(4+) ratio in the bulk and on the glass surface, and to correlate it with the ability of the samples to show catalase mimetic activity. Interestingly, we have found that the bioactive glass with composition 23.2Na2O-25.7CaO-43.4SiO2-2.4P2O5-5.3CeO2 immersed in 0.1 M H2O2 aqueous solution is able to degrade 90% of it in 1 week. The reduction in bioactivity of the glasses with increasing CeO2 content is here rationalized in terms of a lower amount of phosphate groups available for the hydroxyapatite layer formation, after binding with cerium ions. In fact, classical molecular dynamics simulations revealed that the addition of CeO2 leads to the formation of cerium phosphate rich regions. The formation of an insoluble CePO4 crystalline phase is also observed by XRD analysis after thermal treatment of the glass samples.
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 183, 41125 Modena, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Nicolini
authors.forename: Elisa
authors.initials: E
authors.lastname: Gambuzzi
authors.forename: Gianluca
authors.initials: G
authors.lastname: Malavasi
authors.forename: Ledi
authors.initials: L
authors.lastname: Menabue
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Menziani
authors.forename: Gigliola
authors.initials: G
authors.lastname: Lusvardi
authors.forename: Alfonso
authors.initials: A
authors.lastname: Pedone
authors.forename: Francesco
authors.initials: F
authors.lastname: Benedetti
authors.forename: Paola
authors.initials: P
authors.lastname: Luches
authors.forename: Sergio
authors.initials: S
authors.lastname: D'Addato
authors.forename: Sergio
authors.initials: S
authors.lastname: Valeri
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002563:Cerium / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001672:Biocompatible Materials; D010710:Phosphates; D002563:Cerium; C030583:ceric oxide; D017886:Durapatite; D006861:Hydrogen Peroxide; D002374:Catalase; C048083:cerium phosphate