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Abstract:The structural effects of yttrium (Y) and cerium (Ce) are investigated when substituted for sodium (Na) in a 0.52SiO 2 -0.24SrO-(0.24−x)Na 2 O-xMO (where x = 0.08; MO = Y 2 O 3 and CeO 2 ) glass series. Network connectivity (NC) was calculated assuming both Y and Ce can act as a network modifier (NC = 2.2) or as a network former (NC up to 2.9). Thermal analysis showed an increase in glass transition temperature (Tg) with increasing Y and Ce content, Y causing the greater increase from the control (Con) at 493 ∘ C to 8 mol% Y (HY) at 660 ∘ C. Vickers hardness (HV)was not significantly different between glasses. 29 Si MagicAngle Spinning-Nuclear Magnetic Resonance (MAS-NMR) did not show peak shift with addition of Y, however Ce produced peak broadening and a negative shift in ppm. The addition of 4 mol% Ce in the YCe and LCe glasses shifted the peak from Con at −81.3 ppm to −82.8 ppm and −82.7 ppm respectively; while the HCe glass produced a much broader peak and a shift to −84.8 ppm. High resolution X-ray Photoelectron Spectroscopy for the O 1s spectral line showed the ratio of bridging (BO) to non-bridging oxygens (NBO), BO:NBO, was altered, where Con had a ratio of 0.7, HY decreased to 0.4 and HCe to 0.5.

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Abstract:The effect on ion release and cytocompatibility of Yttrium (Y) and Cerium (Ce) are investigated when substituted for Sodium (Na) in a 0.52SiO 2 -0.24SrO-0.24-Na 2 O-MO glass series (where MO = Y 2 O 3 or CeO 2 ). Glass leaching was evaluated through pH measurements and Inductive Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis where the extract pH increased during incubation (11.2 -12.5). Ion release of Silicon (Si), Na and Strontium (Sr) from the Con glass was at higher than that of glasses containing Y or Ce, and reached a limit after 1 day. Ion release from Y and Ce containing glasses reached a maximum of 1800 µg/mL, 1800 µg/mL, and 10 µg/mL for Si, Na, and Sr, respectively. Release of Y and Ce was below the ICP-OES detection limit <0.1 µg/mL. Cell viability of both L929 fibroblasts and MC3T3 osteoblasts decreased for Con, LY, and LCe extracts; HY extracts did not significantly decrease cell viability while YCe and HCe saw concentrationdependent viability decrease (20%, 33% extract concentrations). Bacterial studies saw Con and LCe eliminating >75% of bacteria at a 9% extract concentration. Antioxidant capacity (mechanism for neuroprotection) was evaluated using the ABTS assay. All glasses had inherent radical oxygen species (ROS) scavenging capability with Con reaching 9.5 mMTE.

A bioactive glass series (0.42SiO -0.10Na O-0.08CaO-(0.40 - x)ZnO-(x)Ga O ) was synthesized, and it is efficacy against the Gram (-ve) bacteria Escherichia coli (E. coli), the Gram (+ve) bacteria Staphylococcus aureus (S. aureus), and the fungus Candida albicans (C. albicans), were characterized through liquid broth analysis. The glass series was also seeded in CMC-Dex hydrogels at three different loadings (0.05, 0.10, and 0.25 m ), and the antibacterial and antifungal efficacies of the resulting composites were characterized using both liquid broth and agar diffusion analysis. Liquid broth analysis was conducted using liquid extracts, which for glass samples were obtained after incubation for up to 30 days in both ultrapure water and phosphate buffered saline (PBS), while glass-hydrogel extracts were obtained solely in PBS. Glass extracts (water) decreased C. albicans viability, while those obtained in PBS decreased the viability of both E. coli and C. albicans. Glass-hydrogel extracts exhibited slight inhibition of E. coli and C. albicans. However, none of the liquid extracts decreased S. aureus viability. Glass-hydrogel composites produced inhibition zones in all three microbial cultures, with the greatest efficacy against C. albicans. The results of this study suggest these materials have potential as bone void-filling materials which display antifungal, and possibly, antibacterial properties. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1102-1113, 2017.