DNA origami based Au–Ag-core–shell nanoparticle dimers with single-molecule SERS sensitivity

Abstract

DNA origami nanostructures are used to arrange gold nanoparticles into dimers with defined distance, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). Single dye molecules (TAMRA and Cy3) can be placed into the SERS hot spots, with Raman enhancement up to 1010, which is sufficient to detect single molecules by Raman scattering.

Hybrid Structures for Surface‐Enhanced Raman Scattering: DNA Origami/Gold Nanoparticle Dimer/Graphene

“…In all cases SERS measurements on single AuNPs are accompanied by AFM measurements in order to confirm the origin of each signal. In every SERS series (Figure a–d) the characteristic TAMRA bands are marked with a green star whereby the peaks at ≈1361 and 1654 cm −1 are visible in all spectra and additional peaks at 1222, 1509, 1538, and 1570 cm −1 only appear in some cases. For AuNPs coated by DNA with TAMRA at the 5′‐end (Figure c,d) a slight red‐shift of 4 cm −1 for the two most prominent TAMRA bands is observed resulting in spectral positions of 1357 and 1650 cm −1 , which is attributed to distance‐dependent interactions between the dye molecules and the gold surface.…”

“…Subsequent correlation of AFM and SERS images allows for a direct assignment of SERS signals to defined structures which is illustrated in Figure b (left: AFM image; right: SERS image). Usually, in AFM images of AuDG hybrid structures solely the AuNP dimers are visible (Figure c, white circles) due to the geometrical arrangement of the AuNPs with respect to the DNA origami substrate preventing the DNA origami from flat adsorption . However, when the two AuNPs are attached to one side of the DNA origami substrate and when the structures are located in close proximity to the edge of the graphene flake the apex of the DNA origami triangle might become visible (Figure d, white arrows).…”

“…Due to the addressability of every single DNA staple strand being part of the self‐assembly process, functional units, e.g., gold nanoparticles (AuNPs), can be attached to DNA origami templates with nm precision. Such hybrid structures have been used for the study of plasmonic effects or surface‐enhanced spectroscopies such as fluorescence enhancement or quenching, surface‐enhanced Raman scattering (SERS), and even for single‐molecule SERS …”

FRET efficiency and antenna effect in multi-color DNA origami-based light harvesting systems

“…21,22 Since every staple strand can be addressed and modied individually and separately, different moieties can be arranged with a high local control since the exact position of each staple strand in the DNA origami structure is known. DNA origami structures have been used to create highly sensitive SERS substrates by attaching gold nanoparticle dimers, [23][24][25] to analyze DNA strand breaks induced by low energy electrons 26,27 and UV photons 28 and to arrange different uo-rophores 29,29,30 at precise distances to create nanoscale photonic devices which can be used for example as photonic wires, 15,18 to resolve conformational changes of biomolecules, [31][32][33][34] as logic gates 35,36 and articial light harvesting complexes. 8,10,18 The light harvesting efficiency is in this context typically expressed as an antenna effect (AE), i.e.…”

Fundamentals and applications of SERS-based bioanalytical sensing

“…SERS is a powerful technique that uses the enhancement of the Raman signal of molecules situated in the near vicinity of metallic nanostructures to obtain detailed information regarding the identity of those molecules [33][34][35][36], with sensitivities down to single-molecule level [37][38][39]. The enhancement of the Raman signal is based on two mechanisms: electromagnetic enhancement [40,41] and chemical enhancement [42,43].…”