Magnetic liquid metal scaffold with dynamically tunable stiffness for bone tissue engineering

The stiffness of most biomaterials used in bone tissue engineering is static at present, and does not provide an ideal biomimetic dynamical mechanical microenvironment for bone regeneration. To simulate the dynamic stiffness better during bone repair, the preparation of dynamic materials, especially hydrogels, has aroused researchers' interest. However, there are still many problems limiting the development of hydrogels such as small-scale stiffness changes and unstable mechanical properties. Here, magnetic liquid metal (MLM) was introduced into bone tissue engineering for the first time. A MLM scaffold was obtained by adding magnetic silicon dioxide particles (Fe@SiO2) into galinstan. Furthermore, a porous MLM (PMLM) scaffold was obtained by adding polyethylene glycol as a template to the MLM scaffold. Both scaffolds can respond to external magnetic fields, so changing the magnetic field intensity can achieve a large-scale of dynamic stiffness change. The results showed that the MLM scaffold has good biocompatibility and can promote the osteogenic differentiation of mesenchymal stem cells (MSCs). The PMLM scaffold with dynamic stiffness can promote new bone regeneration and osseointegration in vivo. Our research will open up a new field for the application of liquid metal and bring new ideas for the development of bone tissue engineering materials.