Superparamagnetic Amine-Functionalized Maghemite Nanoparticles as a Thixotropy Promoter for Hydrogels and Magnetic Field-Driven Diffusion-Controlled Drug Release

Superparamagnetic nanoparticle-arrested hydrogel matrices have immense significance in smart soft biomaterials. Herein, we report the synthesis of superparamagnetic nanoparticle-loaded magneto-responsive tough elastomeric hydrogels for dual-responsive drug delivery. In the first phase of work, we carried out room-temperature synthesis of amine-functionalized superparamagnetic iron oxide nanoparticles (IONPs), and in the second phase of work, we demonstrated that IONPs could act as a toughening agent as well as a viscosity modifier for poly­(acrylic acid-co-hydroxyethyl methacrylate) copolymer hydrogels. The hydrogel was tested by Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and continuous-wave-electron paramagnetic resonance (CW-EPR). Moreover, the IONPs affect its gelation time and elasticity significantly, which was also evaluated from its rheological behavior. The compressive mechanical strength (∼120 kPa), elasticity, recovery to original shape (zero permanent set), water uptake, and thixotropic behavior under dynamic stress of the hybrid hydrogels have supported its robustness in the swelled state. The drug release behavior of the hydrogel showed dual parameter dependency (IONPs and cross-linker) and dual responsiveness against both pH and static magnetic field. The delayed network rupturing, dual-responsive drug delivery nature, and noncytotoxic behavior against human live cells could promote this hybrid hydrogel as an ideal alternative for the remotely controlled drug delivery vehicle.