Programmable shape transformation of 3D printed magnetic hydrogel composite for hyperthermia cancer therapy

Recent advances in soft magnetic nanocomposites have enabled myriads of magnetic robots with programmable shape transformation, shedding light on various biomedical applications. However, the complex shape transformation of magnetic hydrogels remains a challenge because of their ultralow magnetization and simple geometry. Here we demonstrate an approach to meet this challenge by fabricating composite structures of magnetic hydrogels and elastomers with extrusion-based 3D printing. Under an alternating magnetic field, magneto-thermo-sensitive hydrogels — poly(N-isopropylacrylamide) (PNIPAm) embedding Fe₃O₄ nanoparticles, can undergo abrupt volume collapse due to magnetothermal effect. The mismatch in the responsiveness of magnetic hydrogels and elastomers enables the shape transformation of the composite structure. We have printed magnetic hydrogels with various geometries and achieved complex shape transformation of the composite structure. The shape transformative structure can simultaneously encase and kill cancer cells (human malignant melanoma cells) through magnetic hyperthermia. ∼50% of cancer cells can be killed by the heated magnetic hydrogel during deformation. This approach may open opportunities for applications in medicine and bioengineering.