*2.4. Degradation studies*

The degradation behaviour of composite fibres was investigated by immersion in Dulbecco's phosphate buffered saline (DPBS, Sigma-Aldrich, Munich, Germany) medium at pH 7.4. Resulting pH values were measured instantly after the immersion of the sample and for different time points, up to 21 days, at 37 ◦C by using a pH meter (HD8705, Delta OHM, Padova, Italy). The pH measurements of different solutions were correlated to the dissolution of ions in the incubation media. In addition, the degradation of PLLA-SBA2 fibres in physiological solutions was assessed by measuring the weight loss [23] for dried fibrous mats after 21 days of DPBS incubation. The percentage of weight loss, *W*<sup>L</sup> %, was computed as 100 × (*W*<sup>0</sup> − *W*r)/*W*0, where *W*<sup>0</sup> and *W*<sup>r</sup> are the initial and the residual weight of the sample, respectively.
