Journal of the American Chemical Society | 14 Nov 2017
S Tanwar, K Haldar and T Sen
We demonstrate the synthesis of Au nanostar dimer with tunable interparticle gap and controlled stoichiometry as-sembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red dye was specifically attached in the junction of the dimerized origami which acts as a Raman reporter molecule. The SERS enhancement factors of single Texas red dye located in the conjunction region in the dimer structures having inter-particle gaps of 7 nm and 13 nm are 2 × 1010 and 8 × 109, respectively, which are strong enough for single analyte detec-tion. The highly enhanced electromagnetic field generated by the plasmon coupling between sharp tips and cores of two Au nanostars in the wide conjunction region allows the accommodation and specific detection of large biomole-cules. Such DNA directed assembled nanoantennas with controlled interparticle separation distance and stoichiome-try, and well-defined geometry can be used as excellent substrates in single molecule SERS spectroscopy and will have potential applications as a reproducible platform in single molecule sensing.
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