Hierarchically Nanostructured Magnetic Hollow Spheres of Fe₃O₄ and γ-Fe₂O₃:  Preparation and Potential Application in Drug Delivery

Abstract

We report for the first time a novel precursor-templated conversion method for the controlled synthesis of hierarchically nanostructured magnetic hollow spheres assembled by Fe 3 O 4 or γ-Fe 2 O 3 nanosheets with a relatively high saturation magnetization. We synthesized hierarchically nanostructured hollow spheres organized by nanosheets of a layer-structured ferrous precursor by a microwave-assisted hydrothermal method in ethylene glycol (EG). Ferric chloride (FeCl 3 ·6H 2 O) was used as the iron source, and EG acted as both a solvent and a reductant to reduce ferric salt to ferrous precursor in the presence of sodium hydroxide (NaOH) and sodium dodecyl benzene sulfonate (SDBS). The precursor was heated to prepare hierarchically nanostructured magnetic hollow spheres assembled by Fe 3 O 4 or γ-Fe 2 O 3 nanosheets, which were surface-modified with poly(ethylene glycol) (PEG). The surface-modified hierarchically nanostructured magnetic hollow spheres were explored as drug carriers. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behaviors of ibuprofen in a simulated body fluid (SBF) were studied. The results indicate that these hierarchically nanostructured magnetic hollow spheres of Fe 3 O 4 or γ-Fe 2 O 3 have a high drug loading capacity and favorable release property for ibuprofen; thus, they are very promising for application in drug delivery. The samples were characterized by XRD, TEM, SEM, TG/DSC, BET, PPMS, FTIR, and UV−vis.