Synthesis and Surface Modification of Spindle-Type Magnetic Nanoparticles: Gold Coating and PEG Functionalization

摘要

In this paper, we describe the synthesis of gold coated spindle-type iron nanoparticles and its surface modification by a thiolated fluorescently-labelled polyethylene glycol (PEG) polymer. A forced hydrolysis of ferric salts in the presence of phosphate ions was used to produce α-Fe2O3 spindle-type particles. The oxide powders were first reduced to α-iron under high temperature and controlled dihydrogen atmosphere. Then, the resulting magnetic spindle-type particles were covered by a shell of gold. The formation of the core@shell structure was driven by a redox-transmetalation reaction between iron(0) at the surface of particles and a gold(III) salt. Protected against oxidation, the Fe@Au core@shell nanoparticles were then grafted with a water soluble fluorescent-PEG-thiol. TEM, XRD, EDX and measurements of magnetic properties of particles confirm 1) the conversion of hematite into iron and 2) their subsequent surface protection with a gold shell. Furthermore, the functionalization of the gold nanoparticle surface with a PEG carrying a fluorescent dye was unambiguously attested by confocal laser scanning microscopy.