Synthesis, characterization and evaluation of bioactivity of glasses in the CaO-SiO₂-P₂O₅-MgO system with different CaO/MgO ratios

Abstract

Bioactive glasses (80Mg, 70Mg, 60Mg and 50Mg) in the system SiO2-CaO-P2O5-MgO were prepared by sol-gel method and then characterized. The structure of the synthesized samples has been studied by X-ray diffraction (XRD), Fourrier Transform Infrared Spectroscopy (FTIR) and Environmental Scanning Electron Microscopy (ESEM). In vitro bioactivity tests were performed in Simulated Body Fluid (SBF). The apparent density and wettability variation with time were measured. The in vitro studies showed the formation of an apatite-like layer covering areas of the material surface. The variation in the CaO/MgO ratio has an influence on the chemical durability and bioactivity. The XRD and FTIR analysis revealed that the samples with larger CaO/MgO ratio exhibited better bioactivity. The results showed that the 50Mg glass which has the higher content of CaO/MgO is hydrophilic sample for the two used fluids (water and SBF). The porosity and hydrophilicity increase with increased the rate of CaO/MgO. The surface of bioglasses became rougher with the increased CaO/MgO ratio, which may lead to a decrease in water contact angle.

Physicochemical and in vitro bioactivity studies of bioactive glasses in the SiO2-CaO-MgO-P2O5, SiO2-Na2O-CaO-P2O5 and SiO2-Na2O-CaO-MgO-P2O5 systems

“…The spectra of the as-prepared samples show the absorption bands of the silicate group in the region 1020-1038 cm −1 , and at 446 cm −1 25 . In addition, for SNCP and SNCMP glasses, bands at 570 and within 788-794 cm -1 are observed and ascribed respectively to the bending vibration mode of P-O in amorphous calcium phosphate and to the symmetric stretching of Si-O-Si bond 25,26 ; however, none of these bands is observed for the as-prepared SCMP glass. A broad OH absorption band at 3330 cm −1 and a weak adsorbed water band ~ 1635-1660 cm −1 appeared in the spectra of as-prepared SCMP and SNCP samples.…”

Bioactive glass doped with zinc-based metal–organic frameworks (Zn/MOF) nanoparticles for antibiotic delivery applications

“…The increase in pH values continues until the tenth day (8.92 ± 0.09, and 8.80 ± 0.02 for BG, and BG/Zn MOF, respectively), then begins to decrease gradually until it reaches 8.26 ± 0.05 and 8.30 ± 0.03 for BG and BG/Zn MOF, respectively, at the end of soaking time. These findings could be explained as follows: at the early stages of incubation, the dissolution of samples takes place leading to Ca 2+ , and Si leaching out from samples, so pH increase occurs rapidly [39]; the Zn +2 release does not contribute to change in pH due to its low content in BG/Zn MOF sample. The decrease in pH may be ascribed to Ca +2 ions precipitation on the surface of the samples due to the attraction of the negative charge of Si-OH groups [46].…”

“…The presence of Zn MOF improved hydroxyapatite formation and caused Ca/P to approach stoichiometric apatite value (Ca/P = 1.67). Ion dissolution from glass samples initiates the formation of hydroxyapatite layer [39].…”

“…Although the low Zn content in BG/Zn MOF sample is favorable from the view Fig. 7 FTIR spectra of the prepared samples after 4 weeks of SBF immersion of decreased toxicity, it is also attributed to the increased ability of hydroxyapatite formation in addition to its advantageous antibacterial effect [39].…”

The unexplored role of alkali and alkaline earth elements (ALAEs) on the structure, processing, and biological effects of bioactive glasses

“…57 Although replacing calcium with other alkaline earth elements may not negatively affect dissolution rates, it can reduce the rate and amount of HAp formed. 58,59 Magnesium has been well studied and described to delay the formation of an apatite layer. 60,61 On the other hand, strontium has been found to assist in apatite formation through strontium-substituted apatite.…”