3D printing of step-gradient nanocomposite hydrogels for controlled cell migration.

In this study, we report the step-gradient nanocomposite (NC) hydrogel generated easily by spatial connection of different nanocomposite hydrogel pastes varying in the concentrations of nanomaterials with the aid of a 3D printing technique. The prepared 3D printed gradient NC hydrogel has self-adhesive properties and is used to direct the migration of fibroblast cells towards the higher concentration of biopolymer-coated silica-based nanomaterials (NMs) within the 3D network of the hydrogel. Furthermore, we demonstrate the potential application of our gradient NC hydrogel in migration and subsequent enhanced osteogenic differentiation of human bone marrow derived mesenchymal stem cells (hBM MSC). The osteogenic differentiation of hBM MSC is achieved in the absence of osteogenic differentiation medium due to the silica-based NMs. The increase in the NM content in the gradient construct promotes hBM MSC migration and results in higher Ca deposition.