Here, this study reports a novel confined-space thermal dewetting strategy for the fabrication of Au nanocups with tunable diameter, height, and size of cup opening. The nanocup morphology is defined by the cup-shaped void space created by a yolk-shell silica template that spontaneously takes an eccentric configuration during annealing. Thermal dewetting of Au, which is sandwiched between the yolk and shell, leads to the desired nanocup morphology. With strong scattering in near infrared, the Au nanocups exhibit superior efficiency as contrast agents for spectral-domain optical coherence tomography imaging. This confined-space thermal dewetting strategy is scalable and general, and can be potentially extended to the synthesis of novel anisotropic nanostructures of various compositions that are difficult to produce by conventional wet chemical or physical methods, thus opening up opportunities for many new applications.

We propose the use of branched gold nanoparticles (B-GNPs) as a contrast agent for optical coherence tomography (OCT) imaging. Our results show that even when the central source of our OCT (1325 nm) is too far from the maximum peak of the plasmon resonance, branched nanoparticles scatter light very efficiently at this wavelength. B-GNPs were tested as a contrast agent in water and agarose-TiO 2 tissue phantoms; the estimated increments in contrast were 9.19 dB and 15.07 dB for branched nanoparticles in water with concentrations of 2.2 × 10 9 NPs/mL and 6.6 × 10 9 NPs/mL, respectively, while for agarose-TiO 2 tissue phantoms the estimated value was 3.17 dB. These results show the promising application of B-GNPs as a contrast agent for tissue imaging using OCT, not only for sources at 1325 nm but also at other central wavelengths located between 800 and 1000 nm.

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In article number https://doi.org/10.1002/adma.201701070, Boris Hyle Park, Yadong Yin, and co‐workers describe the development of a novel “confined‐space thermal dewetting” strategy for the fabrication of gold nanocups with controlled morphologies. By controlling the relative dimension of the silica and polymer layers in the original particles, Au nanocups with tunable diameter, height, and size of cup opening can be produced. The gold nanocups strongly scatter near‐infrared light, and exhibit superior efficiency in enhancing contrast for optical coherence tomography imaging, which uses light to capture high‐resolution images of biological tissue.

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