Combining multiple discrete components into a single multifunctional nanoparticle could be useful in a variety of applications. Retaining the unique optical and electrical properties of each component after nanoscale integration is, however, a long-standing problem1,2. It is particularly difficult when trying to combine fluorophores such as semiconductor quantum dots with plasmonic materials such as gold, because gold and other metals can quench the fluorescence3,4. So far, the combination of quantum dot fluorescence with plasmonically active gold has only been demonstrated on flat surfaces5. Here, we combine fluorescent and plasmonic activities in a single nanoparticle by controlling the spacing between a quantum dot core and an ultrathin gold shell with nanometre precision through layer-by-layer assembly. Our wet-chemistry approach provides a general route for the deposition of ultrathin gold layers onto virtually any discrete nanostructure or continuous surface, and should prove useful for multimodal bioimaging6, interfacing with biological systems7, reducing nanotoxicity8, modulating electromagnetic fields5 and contacting nanostructures9,10.
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This work was supported in part by NIH (R01 CA131797, NSF, 0645080), the Seattle Foundation and the Department of Bioengineering at the University of Washington. X.G. thanks the NSF for a Faculty Early Career Development award (CAREER). We are especially grateful to T. Kavanagh and D. Eaton for fruitful discussions on nanotoxicity, UW Nanotech User Facility for HRTEM, Z. Wang and Y. Ding for TEM image interpretation, D. Chiu and D. Ginger for critical reading of the manuscript and D. Zhang for help with computer graphics.
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Jin, Y., Gao, X. Plasmonic fluorescent quantum dots. Nature Nanotech 4, 571–576 (2009). https://doi.org/10.1038/nnano.2009.193
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