Browsing by Author "Ivanova R."

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    New Glass-Ceramics in the System Ca2SiO4-Ca3(PO4)2—Phase Composition, Microstructure, and Effect on the Cell Viability
    (2025-08-01) Mihailova I.; Dimitrova P.; Avdeev G.; Ivanova R.; Georgiev H.; Nedkova-Shtipska M.; Teodosieva R.; Radev L.
    The CaO-SiO2-P2O5 system is one of the main systems studied aiming for the synthesis of new bioactive materials for bone regeneration. The interest in materials containing calcium-phosphate-silicate phases is determined by their biocompatibility, biodegradability, bioactivity, and osseointegration. The object of the present study is the synthesis by the sol-gel method of biocompatible glass-ceramics in the Ca2SiO4-Ca3(PO4)2 subsystem with the composition 6Ca2SiO4·Ca3(PO4)2 = Ca15(PO4)2(SiO4)6. The phase-structural evolution of the samples was monitored using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and surface area analysis. A powder (20–30 µm) glass-ceramic material containing fine crystalline aggregates of dicalcium silicate and plates of silicon-substituted hydroxyapatite was obtained after heat treatment at 700 °C. After heat treatment at 1200 °C, Ca15(PO4)2(SiO4)6, silicocarnotite Ca5(PO4)2(SiO4), and pseudowollastonite CaSiO3 were identified by XRD, and the particle size varied between 20 and 70 µm. The compact glass-ceramic obtained at 1400 °C contained Ca2SiO4-Ca3(PO4)2 solid solutions with an α-Ca2SiO4 structure as a main crystalline phase. SEM showed the specific morphology of the crystalline phases and illustrated the trend of increasing particle size depending on the synthesis temperature. Effects of the glass-ceramic materials on cell viability of HL-60-derived osteoclast-like cells and on the expression of apoptotic and osteoclast-driven marker suggested that all materials at low concentrations, above 1 µg mL−1, are biocompatible, and S-1400 might have a potential application as a scaffold material for bone regeneration.