Uniting Top-Down and Bottom-Up Strategies Using Fabricated Nanostructures as Hosts for Synthesis of Nanomites

Abstract

Gold nanomites on gold nanotriangles were produced using a combination of bottom-up synthesis and top-down fabrication. Modified gold nanostar protocols were the basis for the synthesis to form the nanomite features on the fabricated structures. Gold nanostars produce some of the strongest signal enhancements in plasmonics due to the large number of sharp features per particle. However, the tendency for the high-aspect-ratio features of nanostars to undergo structural changes and the prevalence of particle aggregation in different solution conditions present challenges for research as well as applications of these particles. As an alternative to solution-based synthesis, top-down fabrication methods have been used to produce plasmonic structures with sharp features with greater stability in different environments and elimination of aggregation issues. These advantages tend to be at the cost of decreased sensitivity compared to synthesized particles with a higher density of high-aspect-ratio features such as nanostars. Here, top-down fabrication is united with bottom-up synthesis to add a high density of surface features to fabricated gold nanotriangles in the form of nanomites. This approach combines advantageous features of both nanomaterial strategies. The nanomite nucleation and growth processes were controlled by altering the reagents and incubation temperatures used in the one-pot synthesis. Fabricated gold nanostructures with different shapes and sizes could be hosts for the nanomites making this hybrid bottom-up/top-down approach a highly versatile route to tunable plasmonic substrates with a high density of hotspot regions for plasmon-enhanced spectroscopy applications.

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