Direct Synthesis of Water-Dispersible Magnetic/Plasmonic Heteronanostructures for Multimodality Biomedical Imaging

Magnetic/plasmonic hybrid nanoparticles are highly desirable for multimodal bioimaging and biosensing. Although the synthesis of heterodimeric nanoparticles has been reported, the products are usually hydrophobic so that post-treatment procedures are required to transfer them into water which are often difficult to perform and cause damages to the structures. Direct synthesis of hydrophilic hybrid nanostructures has remained a grand challenge albeit its immediate advantage of biocompatibility. Herein we report a general seed-mediated approach to the synthesis of hydrophilic and biocompatible M–Fe3O4 (M = Au, Ag, and Pd) heterodimers, in which the size of metals and Fe3O4 can be independently regulated in a wide range. Benefiting from the aqueous synthesis, this approach can be further extended to design more complex heterodimeric structures such as AgPtalloy–Fe3O4, Aucore@Pdshell–Fe3O4, and Aushell–Fe3O4. The hydrophilic nature of our heterodimers makes them readily useful for biomedical applications with...