Multifunctional Janus particles composed of inorganic nanoparticles through emulsion confined assembly

Janus particles, consisting of two or more chemically distinct composites within a single structural system, have attracted significant attention for their solid surfactant functionality, as well as their potential applications in micro/nanomotors and functional materials. Here, we present a simple and robust method to prepare plasmonic Janus particles consisting of a polystyrene-tethered gold nanorod (AuNRs@PS) head and a poly(4-vinylpyridine) (P4VP) head through emulsion confined assembly. The balance of the Janus particles can be finely tuned by adjusting the volume ratio of the AuNRs@PS solution and P4VP solution. The result shows that the diameter ratio (r) of AuNRs@PS_5k/P4VP is proportional to the volume ratio (R) of the AuNRs@PS and P4VP solutions. Furthermore, the obtained Janus particles with AuNR head have a peak absorbance of around 800 nm, which can be applied in photothermal therapy. Additionally, multifunctionality can be achieved by reducing nanoparticle (NP) precursors on a prefabricated scaffold of P4VP or co-assembling P4VP-tethered NPs with AuNRs@PS building blocks. These multifunctional Janus particles hold great potential for applications in micro/nanomotors, catalysts, and biological materials.