Figure 7.

Synthetic scheme for the preparation of the three-layer NPs (left); TEM images of colloids after each synthetic step. ab SiO₂ particles covered with silica-primed Fe₃O₄ NPs (SiO₂–Fe₃O₄). cd SiO₂ particles covered with silica-primed Fe₃O₄ NPs and heavily loaded with Au nanoparticle seeds (SiO₂–Fe₃O₄–Au seeds). e Three-layer magnetic NPs synthesized in a single-step process from particles presented in (c) and (d). Note the uniformity of the gold shell. The inset shows the three-layer magnetic NPs drawn to the wall with a magnet. From [125]