New Glass-Ceramics in the System CaSiO-Ca(PO)-Phase Composition, Microstructure, and Effect on the Cell Viability.

The CaO-SiO-PO 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 CaSiO-Ca(PO) subsystem with the composition 6CaSiO·Ca(PO) = Ca(PO)(SiO). 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, Ca(PO)(SiO), silicocarnotite Ca(PO)(SiO), and pseudowollastonite CaSiO were identified by XRD, and the particle size varied between 20 and 70 µm. The compact glass-ceramic obtained at 1400 °C contained CaSiO-Ca(PO) solid solutions with an α-CaSiO 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, are biocompatible, and S-1400 might have a potential application as a scaffold material for bone regeneration.