Insights into the Seeded-Growth Synthesis of Colloidal Hybrid Nanoparticles

Colloidal hybrid nanoparticles integrate two or more nanocrystal domains into a single architecture that can have properties not found in, or enhanced relative to those of, the individual components. These hybrid nanomaterials are typically constructed using multistep seeded-growth reaction sequences, which are conceptually analogous to the total synthesis approaches used in molecular synthesis. Here, we discuss in detail the synthetic protocols that lead to the formation of three-component Ag-Pt-Fe3O4 and Au-Pt-Fe3O4 heterotrimers. These instructive model systems highlight the important synthetic details that underpin successful hybrid nanoparticle reactions. We provide detailed, step-by-step protocols for generating these materials, focusing on describing and rationalizing the key reaction parameters that need to be rigorously controlled to minimize unwanted nanoparticle byproducts. The importance of comprehensive analysis using a suite of materials characterization tools is highlighted, as such efforts are useful for diagnosing subtle chemical and morphological features that can lead to synthetic bottlenecks throughout the course of the reaction sequences. Finally, we offer strategies for circumventing these commonly encountered problems as well as insights that can lead to increased hybrid nanoparticle yields and improved sample-to-sample reproducibility. Although this work specifically details the synthesis of Ag-Pt-Fe3O4 and Au-Pt-Fe3O4 heterotrimers, these synthetic strategies and protocol guidelines are generally applicable to many other hybrid nanoparticle systems.