posted on 2021-08-19, 15:39authored bySwati Tanwar, Vishaldeep Kaur, Gagandeep Kaur, Tapasi Sen
Engineering hotspots in surface-enhanced
Raman spectroscopy (SERS)
through precisely controlled assembly of plasmonic nanostructures
capable of expanding intense field enhancement are highly desirable
to enhance the potentiality of SERS as a label-free optical tool for
single molecule detection. Inspired by DNA origami technique, we constructed
plasmonic dimer nanoantennas with a tunable gap decorated with Ag-coated
Au nanostars on origami. Herein, we demonstrate the single-molecule
SERS enhancements of three dyes with emission in different spectral
regions after incorporation of single dye molecules in between two
nanostars. The enhancement factors (EFs) achieved in the range of
109–1010 for all the single dye molecules,
under both resonant and nonresonant excitation conditions, would enable
enhanced photostability during time-series measurement. We further
successfully explored the potential of our designed nanoantennas to
accommodate and detect a single thrombin protein molecule after selective
placement in the wide nanogap of 10 nm. Our results suggest that such
nanoantennas can serve as a broadband SERS enhancer and enable specific
detection of target biological molecules with single-molecule sensitivity.