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The ability of Ce-containing bioactive glasses, based on 45S5 Bioglass, to inhibit oxidative stress in terms of reduction in hydrogen peroxide and superoxide (O ), by mimicking the catalase and superoxide dismutase activity is reported in this work. The characterization is performed on the powders of pristine glasses and after the soaking in HO solutions and simulated body fluid. The glass samples are analysed by XPS, XRD, UV-Vis and FT-IR. The best catalyst activities are obtained for the glass with the highest content of cerium (H_5.3 = 5.3 mol% of CeO in the nominal glass composition), and the best Ce/Ce ratio in terms of catalase mimetic activity is found to be a function of HO concentration. Moreover, the detailed study of the surface during the mimic enzymatic activity tests shows the formation of a Ca-P-rich layer on the glass surface, where the presence of Ce ions favours the formation of CePO. The phosphate in turn inhibits the formation of hydroxyapatite, decreasing the bioactivity of the glass with the highest of CeO in the glass composition. This work shows the effect of Ce/Ce ratio towards the catalase mimetic activity and for the first time the superoxide dismutase mimetic activity of Ce-containing 45S5-derived glasses. [ABSTRACT FROM AUTHOR]

Bioceramics, such as silica-based glasses, are widely used in bone and teeth restoration. Nowadays, the association between nanotechnology and pharmacology is one of the most promising research fields in cancer therapy. The advanced processing methods and new chemical strategies allow the incorporation of drugs within them or on their functionalized surfaces. Bioceramics can act as local drug delivery systems to treat bone and teeth diseases. The present paper reports data related to the development of a pH-stimuli responsive bioactive glass. The glass conjugation with 5-aminofluorescein (5-AF), through a pH-sensitive organic spacer, allows to produce a pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favour the release of 5-AF directly at the target site. 5-AF has been chosen as a simple, low cost, non toxic model to simulate doxorubicin, an anticancer drug. As doxorubicin, 5-AF contains an amino group in its structure in order to form an amide bond with the carboxylic functionalities of the glass. Raman spectroscopy and thermal analysis confirm the glass conjugation of 5-AF by means of an amide bond; the amount of 5-AF loaded was very high (≈65 and 44 wt%). The release tests at two different pH (4.2 and 7.4) show that the amount of released 5-AF is higher at acid pH with respect to physiological one. This preliminary datum evidenced that a pH-sensitive drug delivery system has been developed. The low amount of 5-AF released (<1 wt% of the total 5-AF) is due to the very low solubility of 5-AF in aqueous medium. This disadvantage, may be overcome in a dynamic environment (physiological conditions), where it is possible to obtain a drug release system ensuring an effective therapeutic dose for long times and, at the same time, avoiding the drug toxicity. [ABSTRACT FROM AUTHOR]

The present study is aimed at investigating the contribution of two biologically important cations, Mg and Sr, when substituted into the structure of hydroxyapatite (Ca(PO)(OH),HA). The substituted samples were synthesized by an aqueous precipitation method that involved the addition of Mg- and Sr-containing precursors to partially replace Ca ions in the apatite structure. Eight substituted HA samples with different concentrations of single (only Mg) or combined (Mg and Sr) substitution of cations have been investigated and the results compared with those of pure HA. The obtained materials were characterized by X-ray powder diffraction, specific surface area and porosity measurements (N adsorption at 77 K), FT-IR and Raman spectroscopies and scanning electron microscopy. The results indicate that the co-substitution gives rise to the formation of HA and β-TCP structure types, with a variation of their cell parameters and of the crystallinity degree of HA with varying levels of substitution. An evaluation of the amount of substituents allows us to design and prepare BCP composite materials with a desired HA/β-TCP ratio. [ABSTRACT FROM AUTHOR]

Potentially bioactive fluorine-containing glasses of formula 46.2SiO·24.3NaO·(26.9−x)CaO·2.6PO·xCaF [x = (0), 5, 10, 15] have been studied: the study was carried out as a function of fluorine percentage, dimensions and time of soaking in SBF. The results are compared to those obtained in the same conditions for Bioglass 45S5. Due to the high number and different kind of variables/conditions explored by this set of data, the results are rationalized for the first time by means of multivariate data analysis (MDA); in this way it is possible to classify the behaviour of bioglasses toward bioactivity. The presence of fluorine does not inhibit the formation of HA; in particular, for a fast bioactivity (in term of HA crystallization) it will be better to have large particle size or slabs, while for a fast dissolution fine particle sizes should be preferred. [ABSTRACT FROM AUTHOR]

The local and medium-range structure of the 20CaO·20AlO·60SiO glass generated by classical molecular dynamics simulations has been compared to NMR experiments by computing the Al and O NMR parameters and NMR spectra from first-principles simulations. The calculation of the NMR parameters (chemical shielding and quadrupolar parameters), which are then used to simulate solid-state MAS and 3QMAS NMR spectra, is achieved by the gauge including projector augmented-wave and the projector augmented-wave methods on the DFT-PBE relaxed structure. The NMR spectra calculated with the present approach are found to be in excellent agreement with the experimental data, providing an unambiguous view of the local and medium-range structure of aluminosilicate glasses. [ABSTRACT FROM AUTHOR]

This paper shows recent progresses in the field of computer simulations of inorganic glasses. Molecular dynamics simulations and energy minimization methods have been applied to calculate the elastic and transport properties of alkali silicate glasses of compositions xM2O · (100 − x)SiO2 (with x = 0, 10, 15, 20, 25, 30 % mol for M = Li, Na and K) and of a soda-lime glass with composition 15Na2O · 10CaO · 75SiO2, which has been employed to ascertain the effect of the replacement of CaO for Na2O. The excellent agreement of the computed results with the experimental data highlights the important predictive and interpretative role reached by computer simulations techniques. [ABSTRACT FROM AUTHOR]