Addressing the optimal silver content in bioactive glass systems in terms of BSA adsorption

Bioactive glasses doped with silver are aimed to minimize the risk of microbial contamination, and therefore, the influence of silver on the bioactive properties is an intense investigated task. However, the information related to the role played by silver, when added to the bioactive glass composition, on the biocompatibility properties is scarce. This aspect is essential as long as the silver content can influence the blood protein adsorption onto glass surface, affecting thus the material biocompatibility. Therefore, from the perspective of the biocompatibility standpoint, the finding of an optimal silver content in a bioactive glass is an extremely important issue. In this study, silver doped bioactive glasses were prepared by melt-derived technique, which eliminates the pores influence in the protein adsorption process. The obtained glasses were characterized by X-ray diffraction, UV-vis, X-ray Photoelectron (XPS) and Fourier Transform Infrared (FT-IR) spectroscopy, and afterwards they were investigated in terms of protein adsorption. Both UV-vis and XPS spectroscopy revealed the presence of Ag+ ions in all silver containing samples. By increasing the silver content, metallic Ag0 appears, the highest amount being observed for the sample with 1 mol% AgO2. Electron Paramagnetic Resonance measurements evidenced that the amount of spin labeled serum albumin attached on the surface increases with the silver content. The results obtained by analyzing the information derived from Atomic Force Microscopy and FT-IR measurements indicate that the occurrence of metallic Ag0 in the samples structure influences the secondary structure of the adsorbed protein. Based on the results derived from the protein response upon interaction with the investigated glass calcium-phosphate based system it was determined the optimal silver oxide concentration for which the secondary structure of the adsorbed protein is similar with that of the free one. This concentration was found to be 0.5 mol%

Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of Fe2O3 addition

This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P2O5–5B2O3–5Na2O–(29 − x)CaO–16MgO–(x)Fe2O3 and 45P2O5–5B2O3–5Na2O–24CaO–(21 − x)MgO–(x)Fe2O3 where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q2 units with increasing Fe2O3 content. DSC analyses showed an increase in Tg by ~5 °C with an increment of 3 mol% in Fe2O3 content. The thermal properties were also used to calculate processing window (i.e. Tc,ons—Tg) and another parameter, Kgl, to determine the suitability for fibre drawing directly from melt, which equals (Tc,ons—Tg)/(Tl—Tc,ons). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing Fe2O3 content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to Fe2O3 addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing Fe2O3 content

Structural studies of copper doped 2TeO

The FT-IR absorption and Raman scattering were used in order to obtain information concerning the short range order in xCuO·(100-x)[ 2TeO2·PbO·0.2Ag2O] (0 ≤ x ≤ 5 mol%) glasses. Moreover, the changes in tellurium atoms coordination that occurs with copper oxide addition were followed. Both techniques reveal that tellurium is disposed in the network structure in trigonal bipyramids (TeO4), trigonal pyramids (TeO3) along with TeO3+1 polyhedra units. Increasing the CuO content in the glasses changes the coordination of tellurium atoms from 4 to 3 through the so-called 3+1 intermediate units, simultaneously with the increase of the non-bridging oxygen (NBOs) ions amount causing a depolymerization process in the glass structure