Core−Shell Magnetite Nanoparticles Surface Encapsulated with Smart Stimuli-Responsive Polymer: Synthesis, Characterization, and LCST of Viable Drug-Targeting Delivery System

Abstract

We describe here the synthesis of a novel magnetic drug-targeting carrier characterized by a core−shell structure. The core−shell carrier combines the advantages of a magnetic core and the stimuli-responsive property of the thermosensitive biodegradable polymer shell (e.g., an on−off mechanism responsive to external temperature change). The composite nanoparticles are ∼8 nm in diameter with ∼3 nm shell. The lower critical solution temperature (LCST) is ∼38 °C as determined by UV−vis absorption spectroscopy. The carrier is composed of cross-linked dextran grafted with a poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) [dextran-g-poly(NIPAAm-co-DMAAm)] shell and superparamagnetic Fe₃O₄ core. Fourier transform infrared spectroscopy (FTIR) confirmed the composition of the carrier. The synthesized magnetic carrier system has potential applications in magnetic drug-targeting delivery and magnetic resonance imaging.