Gold nanoparticle superstructures with enhanced photothermal effect

Gold (Au) nanomaterials are promising photothermal therapeutic agents for the selective treatment of tumor cells. Further development of correlated techniques greatly depends on the current efforts to enhance the photothermal performance by fabricating novel Au architectures. In this work, water-dispersible spherical superstructures are constructed from original hydrophobic Au nanoparticles (NPs) in place of oil droplets in microemulsion as the templates. Different from the previous reports, Pluronic F127, a nonionic triblock copolymers of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), is employed as the capping agent to directly make the superstructures biocompatible. However, due to the nonionic nature, it is difficult to control the size and morphology of Au superstructures using F127 alone. Additional positive surfactants, such as octadecyl-p-vinylbenzyldimethylammonium chloride, are necessary to assist Au superstructure formation in a controlled manner. The as-prepared Au superstructures, which possess enhanced absorption the in red and near-infrared region, exhibit more efficient photothermal behavior in comparison to individual Au NPs.