The Impact of Stirring Rate on the Crystallinity and Bioactivity of 58S Bioactive Glass

Abstract

In most biphasic composite systems consisting of sol-gel derived bioactive glass and a second system that is usually used as a reinforcing agent, thorough stirring is necessary to prevent the precipitation of the grains of the second system. Consequently, the aim of this work is to investigate the impact of various stirring rates on the crystallinity and bioactivity of a bioactive glass in the system 58S. Sol-gel-derived bioactive glass (58S) was produced as described in literature. During the gelation, stirring rates of 0, 200, 400, 600 and 800 rpms were applied producing, respectively, the corresponding glass powders. The in vitro bioactivity of the powders was tested in Simulated Body Fluid (SBF) for various immersion times, while the solution was renewed after 6h, 24h and then every 2 days. Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD) were used to characterize all materials before and after immersion in SBF solution. FTIR and XRD measurements of all powders revealed mainly the formation of an amorphous glass, while the main crystalline phase was identified to be Ca2SiO4. After immersion in SBF solution for 12h, SEM microphotographs revealed apatite formation on the surface of all samples, while FTIR and XRD confirmed the aforementioned findings. Furthermore, since EDS analysis proved a mean molar Ca/P ratio of about1.7 after 6 days of immersion of all samples- besides those stirred at 400 and 600rpm- it can be assumed that a thick apatite layer was formed covering the whole surface.

Fabrication and multiscale characterization of 3D silver containing bioactive glass-ceramic scaffolds

“…Hydroxyapatite formation, while minimal as evidenced from TEM images (Fig. 6b) and the broad rings in diffraction patterns, can result from the applied heat treatment and the relevant concentrations of the Ca, P ions in the structure [39,40]. Similarly, the formation of metallic silver indicates that the stabilization of silver ions cannot be preserved under the given processing conditions.…”

Sol–gel processing of novel bioactive Mg-containing silicate scaffolds for alveolar bone regeneration

“…These results were confirmed by FTIR spectroscopy, since the FTIR spectrum presented the peaks at 665 and 632 cm À1 , which have been attributed to diopside 20,21 as well as the peaks at 700 and 750 cm À1 that can be assigned to clinoenstatite. 21,22 Finally, even though Ca-olivine has been reported not to present any characteristic bands in the MIR region (4000-400 cm À1 ) of the FTIR spectrum, 23,24 the peak at 800 cm À1 that can be attributed to the symmetric stretching mode of Si-O bonds has been previously connected with the formation of a Caolivine phase. 23,24 Morphological characterization.…”

“…) of the FTIR spectrum, 23,24 the peak at 800 cm À1 that can be attributed to the symmetric stretching mode of Si-O bonds has been previously connected with the formation of a Caolivine phase. 23,24 Morphological characterization.…”

“…23,24 Morphological characterization. The morphology and structure of the fabricated sol-gel scaffolds are illustrated in Figure 2(i).…”

Towards the synthesis of an Mg-containing silicate glass–ceramic to be used as a scaffold for cementum/alveolar bone regeneration

“…However, XRD patterns of 50S20Mg heated at the same temperatures were inconsistent with the FTIR findings, since they all indicated the formation of dicalcium silicate (Ca 2 SiO 4 , ICDD card 70-2450), while the one heated at T 2 presented in addition a small amount of diopside (ICDD card 71-1494). Dicalcium silicate has been previously reported not to present any characteristic bands in the Mid-Infrared (MIR) region (4000-400 cm À 1 ) of the FTIR spectrum [33,34] and this is a possible explanation for the inconsistency of the FTIR and XRD findings at lower temperatures. In the case of 50S20Mg heated at T 3 the FTIR spectrum presented distinct bands at the spectral areas of 600-700 cm À 1 and 850-1100 cm À 1 , which can be attributed to diopside and akermanite (Ca 2 MgSi 2 O 7 ), as illustrated in Fig.…”