Effect of Alumina Incorporation on the Surface Mineralization and Degradation of a Bioactive Glass (CaO-MgO-SiO2-Na2O-P2O5-CaF2)-Glycerol Paste

Abstract

This study investigates the dissolution behavior as well as the surface biomineralization in simulated body fluid (SBF) of a paste composed of glycerol (gly) and a bioactive glass in the system CaO-MgO-SiO2-Na2O-P2O5-CaF2 (BG). The synthesis of the bioactive glass in an alumina crucible has been shown to significantly affect its bioactivity due to the incorporation of aluminum (ca. 1.3–1.4 wt %) into the glass network. Thus, the kinetics of the hydroxyapatite (HA) mineralization on the glass prepared in the alumina crucible was found to be slower than that reported for the same glass composition prepared in a Pt crucible. It is considered that the synthesis conditions lead to the incorporation of small amount of aluminum into the BG network and thus delay the HA mineralization. Interestingly, the BG-gly paste was shown to have significantly higher bioactivity than that of the as-prepared BG. Structural analysis of the paste indicate that glycerol chemically interacts with the glass surface and strongly alter the glass network architecture, thus generating a more depolymerized network, as well as an increased amount of silanol groups at the surface of the glass. In particular, BG-gly paste features early intermediate calcite precipitation during immersion in SBF, followed by hydroxyapatite formation after ca. seven days of SBF exposure; whereas the HA mineralization seems to be suppressed in BG, probably a consequence of the incorporation of aluminum into the glass network. The results obtained within the present study reveal the positive effect of using pastes based on bioactive glasses and organic carriers (here alcohols) which may be of interest not only due to their advantageous visco-elastic properties, but also due to the possibility of enhancing the glass bioactivity upon surface interactions with the organic carrier.

Effect of microwave and probe sonication processes on sol–gel‐derived bioactive glass and its structural and biocompatible investigations

“…050453), and wollastonite (Ca 2 SiO 4 —JCPDS. 310299) . These HCA, HA, calcite, and wollastonite diffractograms characteristic patterns are matched with the obtained peaks.…”

Injectable bioactive glass-based pastes for potential use in bone tissue repair

“…The chemical degradation tests performed earlier for BG1d-BG and BG-gly paste in Tris-HCl at 37 ∘ C in static regime without solution replacement revealed that mass loss after 120 h was 2.81 wt% and 28.46 wt%, respectively [40]. Considering that the BG-gly sample consists of 27 wt% glycerol, one can conclude that relatively fast dissolution of glycerol from glass surface occurs.…”

“…ca. 25 and 50% higher concentrations, respectively, after 3 h immersion in SBF [40]). The enhanced dissolution of Ca 2+ and Mg 2+ is governed by surface chemistry and is due to significant fraction of Q 1 and Q 0 units in the BG-gly material (Table 3).…”

“…Figure 3b presents FTIR spectrum of glycerol with two characteristic bands at 1112 and 1038 cm −1 assigned to C=OH stretching vibrations [26,39]. In turn, the FTIR spectrum of BG-gly paste (Figure 3c) exhibited transmittance bands at 1104 and 1027 cm −1 which could be attributed to stretching vibrations of C-O-R units [26,40] and, according to Gonzalo et al [26], it is an indication that glycerol chemically bonds to the surface of the BG1d-BG glass particles. An appearance of the low frequency transmittance band at 675 cm −1 might serve as an additional evidence to this assumption.…”

Effects of GPTMS concentration and powder to liquid ratio on the flowability and biodegradation behaviors of 45S5 bioglass/tragacanth bioactive composite pastes

“…Interestingly, the BG‐gly paste had a significantly higher bioactivity than as‐prepared BG during immersion in the SBF. This was attributed to the chemical interaction of gly with the surface of BG, which resulted in a strong decrease in the network connectivity of BG, as well as a significant increase in the number of silanol groups on the surface of the paste . Aho et al ., formulated injectable composites of BG S53P4 and poly(ε‐caprolactone‐ co ‐ d , l ‐lactide).…”