Synthesis and characterization of a novel stimuli-responsive magnetite nanohydrogel based on poly(ethylene glycol) and poly(N-isopropylacrylamide) as drug carrier

A novel stimuli-responsive magnetite nanohydrogel (MNHG), namely [poly(ethylene glycol)-block-poly(N-isopropylacrylamide-co-maleic anhydride)(2)]-graft-poly(ethylene glycol)/Fe3O4 [PEG-b-(PNIPAAm-co-PMA)(2)]-g-PEG/Fe3O4, was successfully developed. For this purpose, NIPAAm and MA monomers were block copolymerized onto PEG-based macroinitiator through atom transfer radical polymerization technique to produce PEG-b-(PNIPAAm-co-PMA)(2). The synthesized Y-shaped terpolymer was crosslinked through the esterification of maleic anhydride units using PEG chains to afford a hydrogel. Afterward, magnetite nanoparticles were incorporated into the synthesized hydrogel through the physical interactions. The chemical structures of all synthesized samples were characterized using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. Morphology, thermal stability, size, and magnetic properties of the synthesized MNHG were investigated. In addition, the doxorubicin hydrochloride loading and encapsulation efficiencies as well as stimuli-responsive drug release ability of the synthesized MNHG were also evaluated. The drug-loaded MNHG at physiological condition exhibited negligible drug release values. In contrast, at acidic (pH 5.3) condition and a little bit higher temperature (41 degrees C) the developed MNHG showed higher drug release values, which qualified it for cancer chemotherapy due to especial physiology of cancerous tissue in comparison with the surrounding normal tissue. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46657.