Superparamagnetic Fe3O4 nanoparticles: synthesis by a solvothermal process and functionalization for a magnetic targeted curcumin delivery system

Abstract

Tailoring surface characteristics is necessary for the biomedical application of superparamagnetic Fe₃O₄ nanoparticles. This study developed an approach for the synthesis of Fe₃O₄ nanoparticles with different functional groups grasped on the surface and the influence of different functionalization on the behavior of drug loading and release was also assessed. Monodisperse Fe₃O₄ nanoparticles were first prepared through a novel and simplified solvothermal process. The resulting oleylamine coated nanoparticles (about 4.3 nm in diameter) were carboxylated by meso-2,3-dimercaptosuccinic acid (DMSA) ligand-exchange reactions and further development of amino-functionalized nanoparticles (Fe₃O₄@DMSA–NH₂ NPs) was achieved by chemical reaction with a short chain molecule ethanediamine via 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride activation of the carboxylic acids on the surface of DMSA-coated Fe₃O₄ NPs. The two types of functionalized magnetic nanoparticles with –COOH and/or –NH₂ fabricating their hydrophilicity were characterized and designed as drug carriers to load a natural antitumor drug, curcumin (CUR), which is water-insoluble and instable. The loading process could be described by the Langmuir adsorption isothermal model and pseudo-second-order kinetic model for both functionalized Fe₃O₄ NPs and a stronger drug-loading ability was observed from the Fe₃O₄@DMSA–NH₂ NPs. Furthermore, it's worth noting that all the particles showed a relatively pH-sensitive drug release and the Fe₃O₄@DMSA–NH₂ NPs showed a prolonged drug release, which makes them suitable for use as a scaffold for the design of a pH-sensitive based controlled release carrier. Due to those properties, the functionalized nanoparticles have great promise to be developed as a magnetic targeted drug delivery system for hydrophobic drugs.