Although many lab-scale experiments happen inside a flask, glassware can interfere with some reactions going on inside them. That’s why Qianqian Shi, a research fellow at Monash University working with Monash professor Wenlong Cheng and Duyang Zang of Northwestern Polytechnical University, performed this self-assembly reaction in midair. First, Shi levitates a drop of water using ultrasound waves coming out of the emitter above the drop. Then she adds a suspension containing gold nanocubes on the surface of the water droplet. Because there’s no glassware holding the droplet, the nanocubes quickly spread across its entire outer surface, creating a skin. After about 30–60 min, the water evaporates and the skin of nanocubes collapses, leaving behind a flat bilayer (micrograph shown) of the gold nanocubes floating in the ultrasound wave. Nanoassemblies like these bilayers may have applications in anticounterfeiting and ultrathin lenses.
Credit: Qianqian Shi
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