Gallic acid-grafted hybrid strontium fluoride/polycaprolactone nanocomposite fibers for bone regeneration

This study aimed to develop a new bioactive scaffold by combining the structural characteristics of polycaprolactone (PCL) nanofibers with the therapeutic properties of gallic acid (GA) and strontium fluoride (SrF 2 ) nanoparticles (NPs). Thus, SrF 2 NPs were first synthesized and then incorporated into PCL nanofibers in different amounts (0, 5, 10, and 15 wt%). The resultant nanofibrous mats were then aminolized to immobilize GA via carbodiimide chemistry. As demonstrated by FTIR, GA is successfully immobilized on PCL nanofibers. The crystallinity of PCL nanofiber declined with a lower SrF 2 amount but improved when the SrF 2 amount increased to 15 wt%. The addition of SrF 2 decreases the diameter of the fibers while enhancing their water absorption and tensile strength. The bioactivity results indicated that GA promotes apatite formation on the PCL nanofibers and that SrF 2 increases the amount of deposited apatite. MTT results indicate that both strontium and GA do not have cytotoxic effects on human mesenchymal stem cells. GA enhances PCL wettability, allowing more water or culture medium to penetrate the pores of the scaffold, which increases Sr 2+ release and, consequently, enhances cell adhesion and proliferation, ALP activity, biomineralization, and antibacterial activity. Overall, hybrid SrF 2 -PCL nanocomposite fibers immobilized with GA have significant potential for bone regeneration applications. • Gallic acid grafted-SrF 2 -PCL nanofibrous scaffold were successfully prepared. • GA increases the PCL wettability, causing more Sr2+ to be released. • In PCL nanofibers, apatite deposition is induced by GA and increased by SrF2. • SrF2 enhanced the antibacterial activity of PCL nanofibers grafted with GA.