Plasmonic fluorescent quantum dots

Abstract

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 problem^1,2. 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 fluorescence^3,4. 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 nanostructures^9,10.