SERS-like Plasmonic Enhancement of Raman Spectroscopy in DNA Origami-based Complex Metallic Nanostructures
Mauricio Pilo-Pais
We utilize complex metallic nanostructures based on DNA origami templates with tailored plasmonic resonances to engineer an artificial SERS-like substrate. Briefly, gold nanoparticles (~5 𝑛) are attached at selected places within a DNA-origami “nano-breadboard” (~70𝑥9 𝑛) and later enlarged, and even fused, by electroless deposition of silver. By this method, we are able to control the structures' size and shape, and therefore their plasmonic resonances. We work with tetramer structures shown in Figure 1b and perform Raman spectroscopy of chemisorbed Raman active molecules such as 4-aminobenzenethiol, which are chosen based on the plasmonic resonance frequency of the structure. The strong localization of the electromagnetic fields at the so-called “hot-spots” results in SERS-like enhancement of the observed signal (inset Figure 1b) compared to the control sample of Figure 1a, in which only individual metallic particles are present, but not the assemblies. A decay of the SERS signal as a function of exposure time is observed, possibly due to the “burning” of the molecules located at the hot spots. The flexibility of the design and multiply parallel nature of the method should allow us to fabricate optimum structures for a desired plasmonic application.
