Solution preparation

The PCL solution was prepared by dissolving 14% (w/v) of PCL pellets (average Mw 80,000, Sigma Aldrich, USA) in formic acid (98–100%, Fisher Chemical, Fisher Scientific, Sweden), and was left to stir overnight on a magnetic stirrer at 400 rpm. The PCL/Gt solution was prepared by dissolving and stirring 14% PCL in formic acid for 3 h until a clear solution was obtained followed by the addition of 30 w% (with respect to PCL weight) of Gt from porcine skin (gel strength ~300 g Bloom, Type A, Sigma Aldrich, USA), and was left to stir overnight at 400 rpm.

The BG nanoparticles (Bioglass nanoparticles; Nanostreams, Egypt: NS0001) were manufactured by the sol-gel technique with a composition of 45% silica, 25% CaO, 25% Na₂O, and 5% P₂O_5, and a particle size of less than 10 nm. The PCL/Gt/BG composite scaffold was prepared by adding 3 w% (with respect to PCL weight) of BG to a PCL/Gt solution prepared as previously mentioned, where 0.042 g BG powder was weighed and dispersed in the PCL/Gt solution after complete dissolution of the polymers. The composite solution was left to stir overnight at 600 rpm and then was placed in an ultrasonic bath for 10 min and that solution was immediately electrospun [20]. On the other hand, to obtain BG nanofibers and due to the difficulty of spinning BG alone, PCL was chosen as a suitable polymer to incorporate BG. The PCL/BG solution was prepared by dissolving 14% PCL in formic acid for 3 h, after which 3% BG powder was added and left to stir overnight at 600 rpm, then was placed in an ultrasonic bath for 10 min and immediately electrospun. The preparation of solutions was done at room temperature (22 ± 1 °C).