4D Printed Shape Morphing Biocompatible Materials Based on Anisotropic Ferromagnetic Nanoparticles

摘要

Shape morphing materials, especially those fabricated by 4D printing, aregaining much attention due to their versatility of actuation and capability ofbeing programmed in advance. These materials become particularly interestingfor biomedical applications where implant materials could be remotelyactuated, exerting a force on the surrounding tissues and cells. However,applications in this field have been restricted due to the biocompatibility of thematerials and the character of the required stimuli, generally not compatiblewith physiological environments. Magnetic nanoparticles (MNPs) representa great opportunity to this end; however, the actuation results in a uniformmovement toward the magnet that requires anchoring of the object. Here, forthe first time, the application of anisotropic Fe_3O_4 MNPs is described, and synthesizedby a novel and easy route, that can be aligned on pre-defined patternswithin objects printed by digital light processing, resulting in materials thatcan be actuated remotely (4D printing). These nanoparticles (178 nm × 55 nm),show good biocompatibility when directly seeded on top of human mesenchymalstem cells, despite being uptaken. Most importantly, the alignmentof the MNPs can tune the movement of fabricated nanocomposite materials,resulting in complex movements of attraction or repulsion depending on thedirection of the applied magnetic field.