Fe3O4-nanoparticle-functionalized 3D-printed injectable microgel

Magnetic Fe 3 O 4 nanoparticles have attached attention in bone tissue engineering because of their superior magnetism and great biocompatibility. However, some disadvantages such as the potential risk of agglomeration impair their applications. Here, we proposed a hybrid magnetic nanocomposite microgel by the integration of Fe 3 O 4 nanoparticles and digital lighting processing (DLP) three-dimensional (3D) printing technology. The 3D-printed microgels could be precisely customized by printing the mixture of gelatin methacryloyl (GelMA) solution and polydopamine-coated Fe 3 O 4 nanoparticles, in which polydopamine decoration improved the hydrophilicity and distribution of the incorporated Fe 3 O 4 . The degradable microgels could be injected through a 22-G needle while retaining their original shape after injection. Interestingly, the addition of Fe 3 O 4 nanoparticles into GelMA solution displayed improved printing accuracy. Moreover, these magnetic microgels were biocompatible in vitro and in vivo. After induction within osteogenic medium, addition of nanoparticles upregulated the osteogenic gene expression of rat bone mesenchymal stem cells (BMSCs). In a word, this work provides a magnetic microplatform, which shows great potential in bone tissue engineering.