ABSTRACT
Magnetic nanoparticles (MNPs) have unique properties suitable for numerous biomedical applications. Here, the utility of MNPs for drug delivery applications were examined through two features: magnetic capture and hyperthermia-triggered release. Magnetic localization of the nanoparticles was investigated using iron oxide nanoparticles in simulated blood flow, with the effectiveness of magnetic capture tested as a function of field strength, vessel diameter, flow rate, and the presence of blood proteins. The dispersion quality and viscosity also impact capture. After localization, drug release can be triggered using MNPs imbedded in thermosensitive hydrogels. The tuning of the lower critical solution temperature in poly(N-isopropylacrylamide-co-acrylamide) gels allows triggering to release a drug when mild heating is applied. Thermally modulated release showed that 5-fluorouracil, an anticancer agent, could be effectively squeezed from gels containing 90% NIPAAm upon heating. Additionally, MNPs were successfully dispersed into hydrogels with minimal visible agglomerations, and were largely retained within the hydrogel structure despite their size of less than 10 nm. Magnetic heating of hydrogels with imbedded MNPs was demonstrated. The materials described herein provide a reasonable foundation for the design of magnetothermally responsive gels, which have the potential for triggered drug release using a magnetic field applied from outside of the body.
