Rotating magnetic field-controlled fabrication of magnetic hydrogel with spatially disk-like microstructures

Abstract

Composite biomaterials with controllable microstructures play an increasingly important role in tissue engineering and regenerative medicine. Here, we report a magnetic hydrogel composite with disk-like microstructure fabricated by assembly of iron oxide nanoparticles during the gelation process in the presence of rotating magnetic field. It should be mentioned that the iron oxide nanoparticles here were synthesized identically following techniques of Ferumoxytol that is the only inorganic nanodrug approved by FDA for clinical applications. The microstructure of nanoparticles inside the hydrogel was ordered three-dimensionally due to the twist of the aligned chains of magnetic nanoparticles which leads to the lowest state of systematic energy. The size of microstructure can be tuned from several micrometers to tens of micrometers by changing the assembly parameters. With the increase of microstructure size, the magnetothermal anisotropy was also augmented. This result confirmed that the assembly-induced anisotropy can occur even for the several micron aggregates of nanoparticles. The rotating magnetic field-assisted technique is cost-effective, simple and flexible for the fabrication of composite hydrogel with ordered microstructure. We believe it will be favorable for the quick, green and intelligent fabrication of some composite materials.