DNA Origami Directed Assembly of Gold Bowtie Nanoantennas for Single-Molecule Surface-Enhanced Raman Scattering

Metallic bowtie nanoarchitectures can produce dramatic electric field enhancement, which is advantageous in single-molecule analysis and optical information processing. Plasmonic bowtie nanostructures were successfully constructed using a DNA origami-based bottom-up assembly strategy, which enables precise control over the geometrical configuration of the bowtie with an approximate 5 nm gap. A single Raman probe was accurately positioned at the gap of the bowtie. Single-molecule surface-enhanced Raman scattering (SM-SERS) of individual nanostructures, including ones containing an alkyne group, was observed. The design achieved repeatable local field enhancement of several orders of magnitude. This method opens the door on a novel strategy for the fabrication of metal bowtie structures and SM-SERS, which can be utilized in the design of highly-sensitive photonic devices.