*2.1. Bioactive Glass Synthesis and Characterization*

The SBA2 glass has the following nominal composition (mol %): 48% SiO2, 18% Na2O, 30% CaO, 3% P2O5, 0.43% B2O3, 0.57% Al2O3 and was synthesised by melt-quenching route, as detailed elsewhere [7,32,33]. Briefly, reagent-grade reactants [SiO2, Na2CO3, CaCO3, Ca3(PO4)2, H3BO3 and Al2O3] were melted in a platinum crucible at 1450 ◦C for 1 h (Carbolite HTF 1800, CARBOLITE GERO, Neuhausen, Germany), the melt was then quenched in water to obtain a frit. The frit was ball milled in aqueous medium. The grain size distribution of milled SBA2 was estimated using a particle size analyser (Sympatec Helos H0621, kindly performed at CERICOL Research Centre, Sovigliana, Vinci (Firenze), Italy); the specific surface area (SSA) of milled SBA2 was assessed by using the Brunauer-Emmet-Teller (BET, ASAP2020Plus-Micromeritics, Aachen, Germany) method [39]. The obtained glass powder was analysed morphologically and compositionally by scanning electron microscopy (SEM, FEI QUANTA INSPECT 200, Eindhoven, The Netherlands) and energy dispersive X-ray spectrometry (EDS) (EDAX PV 9900, Weiterstadt, Germany). Thermal properties were determined by differential thermal analysis (DTA–404 PC instrument, Netzsch, Selb, Germany), in a temperature range of 20–1300 ◦C, using a heating rate of 10 ◦C/min and high-purity alumina as reference.
