SF/HAP composite hydrogels with different HAP contents (0–3 wt%) were named as SF-0, SF-1, SF-2, and SF-3 respectively. Table 1 shows the compositions of SF/HAP composite hydrogels.Table 1Sample code and composition of SF/HAP composite hydrogelsSample nameSF concentration (wt%)HAP concentration (wt%)PVP concentration (wt%)SF only7.90.01.0SF-1% HAP7.91.01.0SF-2% HAP7.92.01.0SF-3% HAP7.93.01.0