Fe ₃O ₄/Au/Fe ₃O ₄ nanoflowers exhibiting tunable saturation magnetization and enhanced bioconjugation

Composite nanoparticles have proved to be promising in a wide range of biotechnological applications. In this paper, we report on a facile method to synthesize novel Fe ₃O ₄/Au/Fe ₃O ₄ nanoparticles (nanoflowers) that integrate hybrid components and surface types. We demonstrate that relative to conventional nanoparticles with core/shell configuration, such nanoflowers not only retain their surface plasmon property but also allow for 170% increase in the saturation magnetization and 23% increase in the conjugation efficiency due to the synergistic co-operation between the hierarchical structures. Moreover, we demonstrate that the magnetic properties of such composite nanoparticles can be tuned by controlling the size of additional petals (Fe ₃O ₄ phase). These novel building blocks could open up novel and exciting vistas in nanomedicine for broad applications such as biosensing, cancer diagnostics and therapeutics, targeted delivery, and imaging. © 2012 The Royal Society of Chemistry.