Magnetic and electrically responsive hydrogel networks were developed for drug-delivery applications. The hydrogel matrices were synthesized by the polymerization of acrylamide monomer in the presence of carboxymethylcellulose (CMC) or methylcellulose (MC) with N,N-methylenebisacrylamide, a crosslinker with the redox initiating system ammonium persulfate/tetramethylethylenediamine. The magnetic nanoparticles were generated throughout these hydrogel matrices by an in situ method by the incorporation of iron ions and their subsequent reduction with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNCs) were developed with various CMC and MC compositions. The synthesized HGMNCs were characterized with spectral (Fourier transform infrared and ultraviolet-visible spectroscopy), X-ray diffraction, thermal, and microscopy methods. These HGMNCs contained iron oxide (Fe3O4) nanoparticles with an average particle size of about 22 nm, as observed by transmission electron microscopy. The dielectrical properties of the pure hydrogel (HG); the hydrogel loaded with iron ions, or the hydrogel iron-ion composite (HGIC); and the HGMNCs were measured. These results suggest that HGMNCs exhibited higher dielectric constants compared to HG and HGICs. The curcumin loading and release characteristics were also measured for HG, HGIC, and HGMNC systems. These data revealed that there was a sustained release of curcumin from HGMNCs because of the presence of magnetic nanoparticles in the hydrogel networks. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 1364-1375, 2011