Facile solvothermal synthesis of monodisperse superparamagnetic mesoporous Fe3O4 nanospheres for pH-responsive controlled drug delivery

In the present work, monodisperse Fe3O4 nanospheres with typical mesoporous structures and superparamagnetic characteristics were synthesized through a simple solvothermal approach. Various characterization experiments including SEM, TEM, XRD, XPS, BET and SQUID were performed to investigate in detail the morphology, microstructure, composition and physicochemical properties of the prepared Fe3O4 nanospheres. It was found that the average diameter of Fe3O4 nanospheres was determined to be about 207.3 nm with a relatively narrow size distribution. The analysis of nitrogen adsorption/desorption isotherms indicated that Fe3O4 nanospheres represented typical mesoporous structures having a surface area of 20.68 m2/g. The magnetic property measurements demonstrated that the synthesized nanospheres behaved as superparamagnetic with a high saturation magnetization of 97.5 emu/g. Most importantly, the mesoporous Fe3O4 nanospheres could be utilized as a potential anti-cancer drug carrier for doxorubicin hydrochloride (DOX). The drug loading capacity and in vitro drug release behavior of DOX in phosphate buffered solutions under different pH values (4.0, 5.5 and 7.4) were examined. The results showed that the developed drug delivery system based on mesoporous Fe3O4 nanospheres exhibited a high drug loading capacity and a controlled drug release behavior.