Osteogenic differentiation of the MSCs on silk fibroin hydrogel loaded Fe3O4@PAA NPs in static magnetic field environment

The combination of static magnetic field and magnetic materials for bone tissue repair provides a remote, minimally invasive, and uncomplicated treatment method. Although materials based on Fe3O4 nanoparticles (Fe3O4 NPs) have been widely applied in bone tissue regeneration, the high mobility of Fe3O4 NPs and the oxidative stress involving hydrogen peroxide (H2O2) limit its applications. In this work, silk fibroin (SF) hydrogel was selected to astrict the flowability of Fe3O4 NPs. SF has strong biocompatibility and inducement to the osteogenic differentiation of mesenchymal stem cells (MSCs). In order to reduce the influence of oxidative stress, polyacrylic acid (PAA) was employed to modify the Fe3O4 NPs. The results indicated that Fe3O4@PAA nanoparticles (Fe3O4@PAA NPs) eliminated about 40 % H2O2 in 3 hrs and reduced hydroxyl radicals produced by Fenton reaction. Intracellular studies have shown that SF hydrogel contained Fe3O4@PAA NPs reduced intracellular ROS-induced damage and thus improved cell activity. Compared with other groups, the ALP activity, mineralization ability and collagen secretion level of MSCs on SF hydrogel with Fe3O4@PAA NPs were higher when magnetic field exists.