139 diffractometer

The hybrid powders were obtained using an agate mortar. As reported by Kokubo [36 (link)], to evaluate their bioactivity, the materials were soaked for 7, 14 and 21 days in a simulated body fluid (SBF); the ion concentration in SBF is nearly equal to that in human blood plasma and the solution temperature fixed at 37 °C. The reaction of hydroxyapatite nucleation is affected by the total surface area of the material exposed to SBF and its volume; thus, a constant ratio was maintained, according to literature [36 (link),53 (link),54 (link)]. Then, the SBF solution containing the materials was exchanged every 2 days, to minimize the decrease of the ionic species due to the formation of biominerals in the SBF. After 7, 14 and 21 days the samples, were removed from the SBF and then air-dried in a desiccator. To evaluate the ability to form an apatite layer on their surfaces, Quanta 200 SEM (FEI, Eindhoven, The Netherlands), equipped with energy-dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FT-IR) were used. Furthermore, the apatite layer on the hybrids materials was analyzed by XRD analysis using a Philips 139 diffractometer equipped with a PW 1830 generator, tungsten lamp and Cu anode, where the source 140 of X-ray is given by a Cu-Kα radiation (λ = 0.15418 nm).

The bioactivity of the different materials was evaluated using the simulated body fluid (SBF) solution [15 (link)], in which the ion concentration is nearly equal to that in human blood plasma. The formation of hydroxyapatite on the material’s surface was observed by Quanta 200 SEM (FEI, Eindhoven, the Netherlands), equipped with an energy-dispersive X-ray (EDX), after soaking in SBF for 21 days at 37 °C. The reaction of hydroxyapatite nucleation is affected by the total surface area of the material exposed to SBF and its volume; thus, a constant ratio was maintained, according to the literature [15 (link),16 (link),17 (link)]. Also, apatite layers on the hybrid materials were analyzed by XRD analysis using a Philips 139 diffractometer, equipped with a PW 1830 generator, a tungsten lamp and a Cu anode, where the source 140 of the X-ray is given by the Cu-Kα radiation (λ = 0.15418 nm).

The simulated body fluid (SBF) solution was used for 7, 14, 21 days at 37 °C to study the hybrids’ bioactivity [21 (link)]. The materials powders were obtained using a mortar. The FTIR and XRD analysis were used to evaluate the apatite formation. XRD analysis was carried out using a Philips 139 diffractometer (Amsterdam, The Netherlands) equipped with a PW 1830 generator, tungsten lamp and Cu anode, where the source 140 of X-ray is given by a Cu-Kα radiation (λ = 0.15418 nm). The nucleation of biominerals on the samples could allow the depletion of the ionic species in the SBF, to overcome this problem the solution was replaced every 2 days. The ratio between the total exposed surface and the volume solution was chosen in agreement with the literature. After the exposure, the samples powders were dried in a glass desiccator (Sigma-Aldrich, St. Louis, MO, USA), and then subjected to FTIR analysis.”