Fabrication of iron oxide core/gold shell submicrometer spheres with nanoscale surface roughness for efficient surface-enhanced Raman scattering

A method to synthesize Fe₃O₄ core/Au shell submicrometer structures with very rough surfaces on the nanoscale is reported. The Fe₃O₄ particles were first modified with uniform polymers through the layer-by-layer technique and then adsorbed a lot of gold nanoseeds for further Au shell formation. The shell was composed of a large number of irregular nanoscale Au particles arranged randomly, and there were well-defined boundaries between these Au nanoparticles. The Fe₃O ₄ core/Au shell particles showed strong plasmon resonance absorption in the near-infrared range, and can be separated quickly from solution by an external magnet. This kind of very rough Fe₃O₄ core/Au shell multicomponent was used in the adsorption of 4-aminothiophenol and as a substrate for detection by surface-enhanced Raman spectroscopy.