Osteogenic effects of inductive coupling magnetism from magnetic 3D printed hydrogel scaffold

The surface of iron oxide nanoparticles was chemically modified before being embedded in a chitosan hydrogel and for the first time, made into a scaffold by three-dimensional printing. The nanoparticles were embedded in the scaffold so that they would not be ingested by the surrounding tissue cells. The effects of the inductive coupling magnetism on bone cells were studied in the presence of an external magnetic force. Results from the FTIR and surface zeta potential analyses suggested that the citrate modification of the nanoparticles was successful. TEM images showed that the modification helped reduce the sizes of the agglomerates from 1237 nm to 408 nm. The negative charge on the particle surface formed ionic interaction with the chitosan in the solution. The smaller and charged particles evenly dispersed in a chitosan solution without blocking the extruding nozzle during three-dimensional printing. With the presence of the inductive coupling magnetism, osteoblast cells had a higher proliferation, type 1 collagen production, alkaline phosphatase expression, and mineralization (p < 0.01). The morphology of the osteoblast cells appeared normal and elongated. At the end of 21 days the cells proliferated into the interconnected pores as seen in the SEM images. Inductive coupling was shown to have invoked additional osteogenic responses in bone cells aside from the positive effects from the external magnetic force. The novel magnetic scaffold provided a potential alternative for bone tissue repair using magnetic therapy.