Is non-buffered DMEM solution a suitable medium for in vitro bioactivity tests?

Several laboratories had tested bioactivity of the materials in commercially available solution DMEM (Dulbecco's Modified Eagle's Medium) that is normally used for cultivation of cell cultures. The objective of this work was to find out whether it is possible to replace TRIS-buffered SBF currently used for bioactivity tests with the non-buffered DMEM solution. To understand the role of the organic part of the DMEM solution in the process of crystallization, we have prepared non-buffered solution simulating only its inorganic part (identified as I-solution). It was found that under static-dynamic test conditions calcite (CaCO3) and the amorphous phase of calcium phosphate (ACP) formed on the surface of the glass-ceramic (45S5 bioactive glass based) scaffold exposed to both solutions. Additionally, halite (NaCl) formed at the beginning of exposure to DMEM. Hydroxyapatite phase was not detected on the surface in either non-buffered solution. Organic components contained in the DMEM solution failed to prevent formation of crystalline phases. The present results indicate that it is not recommendable to use DMEM for bioactivity tests of glass-ceramic materials due to its low concentration of Ca2+ ions, high concentration of HCO 3- ions and the necessity to maintain sterile environment during the test. © 2014 the Partner Organisations

Voltammetric measurement of the Pt electrode capacity and the determination of the polyvalent ions diffusion coefficients in the glass melt

The temperature dependence of diffusion coefficients of the polyvalent ions (iron and chromium)is one of characteristic structure parameters in given glass melt. The new voltammetry arrangement with triangular shape of the potential and the three-ele

Signs of degradation of czech art nouveau mosaic glasses

Analyses of Art Nouveau mosaics from the church of St. Simon and Juda in Dolín near Slaný and from Holovousy, both most likely made by the workshop of Viktor Foerster, have shown that the author used the NaO-PbO-SiO 22 glass type and that he used the same glass also for restoration of The Last Judgment mosaic at the Prague Castle in 1890-1910. Despite the fact that lead glasses are more durable than potassium glasses, the material investigations identified corrosion processes on the surface of the glass pieces (tesserae) depending on their composition. Apart from the analyzed mosaic NaO-PbO-SiO2 glasses, we also used ancient sodium glasses (NaO-CaO-SiO2) and 22 potassium glasses (K2O-CaO-SiO2) from archaeological finds in Opava to demonstrate their different chemical durability. We also paid attention to fixation binders used in Art Nouveau mosaics. Inappropriate use of gypsum-containing binders is a significant cause of disintegration of the mosaics. Gypsum and gypsum-lime plasters are very sensitive to humidity. Capillary action of water is a very serious problem that endangers the overall lifespan of any mosaic

Cobalt‐containing spherical glass nanoparticles for therapeutic ion release

Bioactive glass nanoparticles (BGNPs) can be internalized by cells, allowing the intracellular release of dissolution products with therapeutic benefit. Different therapeutic ions can be incorporated into the glass network that can promote angiogenesis via simulation of hypoxia conditions and consequent activation of pro-angiogenic genes. Here, novel monodispersed spherical dense BGNPs were obtained by a modified Stöber method with the SiO2–CaO–CoO composition, with diameters of 92 ± 1 nm, with cobalt as the pro-angiogenic ion. The presence of Co2+ species and the role of Co and Ca as network modifiers in the silica glass were confirmed by X-ray photoelectron spectroscopy and 29Si solid-state magic-angle spinning nuclear magnetic resonance, respectively. Controlled Co2+ ion release was observed in culture media, and no cytotoxicity was observed by (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cell viability assay on human osteosarcoma cells in direct contact with the nanoparticles. This study demonstrated that Co2+ ions can be incorporated into dense and spherical BGNPs, and these materials exhibit great potential as intracellular ion delivery systems with therapeutic properties