2.1.3. Cu-Substituted MBG Microspheres

Cu-substituted MBG microspheres (nominal molar ratio Cu/Ca/Si=2/13/85, hereafter named as MBG\_Cu2%\_SD) were synthesized following the aerosol-assisted spray-drying method reported by Pontremoli, Boffito et al. [16]. Briefly, 2.030 g of Pluronic P123, acting as template, were dissolved in 85 g of ddH2O. Simultaneously, in a separate batch, a solution of 10.73 g of TEOS was pre-hydrolyzed under acidic conditions using 5 g of an aqueous HCl solution at pH 2. The solution with TEOS was then added drop-wise into the template solution and kept stirring for half an hour. Then, 0.163 g of CuCl2 and 1.86 g of Ca(NO3)2 · 4H2O were added. The final solution was stirred for 15 min and then sprayed with a Büchi, Mini Spray-Dryer B-290 (Büchi Labortechnik AG, Flawil, Switzerland), using N2 as atomizing gas (inlet temperature 220 ◦C, N2 pressure 60 mm Hg, feed rate 5 mL min−1). The obtained powder was finally calcined at 600 ◦C in air for 5 h at a heating rate of 1 ◦C min−<sup>1</sup> using a Carbolite 1300 CWF 15/5 (Carbolite Ltd., Hope Valley, UK).
