HEPES-involved hydrothermal synthesis of Fe3O4 nanoparticles and their biological application

Abstract

A simple one-step hydrothermal route was developed for the synthesis of magnetite (Fe₃O₄) nanoparticles in HEPES solution, using FeCl₂ as the Fe(II) precursor. It was found that HEPES played an important role in the fabrication of Fe₃O₄ nanoparticles, where HEPES could act as a weak antioxidant to prevent the complete oxidation of Fe(II) to Fe(III). The possible formation mechanism of HEPES-coated Fe₃O₄ nanomaterials was also discussed. In the reaction system, the influence of inorganic anions on the morphologies of Fe₃O₄ nanostructures was also investigated. The as-synthesized spherical Fe₃O₄ nanoparticles with a concentration of 5–100 μg mL⁻¹ exhibited nontoxicity towards HUVEC normal cells, indicating their potential application in biology. Combining the preparation of Ag and Au nanoparticles in HEPES solution, Ag/Fe₃O₄ and Au/Fe₃O₄ nanocomposites were successfully synthesized by a two-step method, which showed excellent antibacterial properties against S. aureus. Furthermore, the Ag/Fe₃O₄ and Au/Fe₃O₄ nanocomposites could be recycled and reused due to their superparamagnetic properties and retained their antibacterial activities.