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Surface‐enhanced fluorescence using AuNPs can be applied in various fields such as highly sensitive single‐molecule detection, biomolecule sensing, and nanoscale optical control. This surface enhancement effect depends on the size and shape of the AuNP and the relative position with respect to the fluorescent molecule. Therefore, the technical question is whether the excited plasmons of the AuNPs can be coupled and the fluorescent molecules can be fixed to the electric field “hot spot” that is locally enhanced. Studies have been conducted to systematically control surface‐enhanced fluorescence by designing the size and position of multiple AuNPs and the position of fluorescent molecules using a DNA origami structure [95]. Two AuNPs (100 nm) were fixed to a tower‐shaped DNA origami structure (height 220 nm, diameter 15 nm) with a gap of 23 nm, and dye molecules were introduced into the space (Figure 1.12d). By using this structure, the fluorescence of the dye molecules located in the hot spots between AuNPs was enhanced up to 117 times. Using this plasmonic structure, a single‐stranded DNA strand (anchor) was placed at the hot spot, and single‐molecule binding and dissociation of a complementary strand DNA strand to a dye molecule was detected (Figure 1.12d). Dynamic single‐molecule detection of biomolecules in a short time (~10 μs) at low excitation energy was realized with this system.