DNA‐Directed Self‐Assembly of Core‐Satellite Plasmonic Nanostructures: A Highly Sensitive and Reproducible Near‐IR SERS Sensor

Abstract

The excitation of surface plasmons in metallic nanostructures provides an opportunity to localize light at the nanoscale, well below the scale of the wavelength of the light. The high local electromagnetic field intensities generated in the vicinity of the nanostructures through this nanofocusing effect are exploited in surface enhanced Raman spectroscopy (SERS). At narrow interparticle gaps, so‐called hot‐spots, the nanofocusing effect is particularly pronounced. Hence, the engineering of substrates with a consistently high density of hot‐spots is a major challenge in the field of SERS. Here, a simple bottom‐up approach is described for the fabrication of highly SERS‐active gold core‐satellite nanostructures, using electrostatic and DNA‐directed self‐assembly. It is demonstrated that well‐defined core‐satellite gold nanostructures can be fabricated without the need for expensive direct‐write nanolithography tools such as electron‐beam lithography (EBL). Self‐assembly also provides excellent control over particle distances on the nanoscale. The as‐fabricated core‐satellite nanostructures exhibit SERS activities that are superior to commercial SERS substrates in signal intensity and reproducibility. This also highlights the potential of bottom‐up self‐assembly strategies for the fabrication of complex, well‐defined functional nanostructures with future applications well beyond the field of sensing.

DNA-embedded Au–Ag core–shell nanoparticles assembled on silicon slides as a reliable SERS substrate

“…For the assembled core-satellite structure by pure Au NPs, the surface plasmon resonance has been found to be at $650 nm. 26 However, in this study, the surface plasmon resonance of the core-satellite structure blue-shied because of the Ag shell on the satellite nanoparticles, leading the surface plasmon resonance closer to 633 nm. Therefore, the 633 nm laser resulted in a higher enhancement than the 785 nm laser.…”

Three-Dimensional SERS Substrates Formed with Plasmonic Core-Satellite Nanostructures

“…Many of the core-satellite nanostructures used for SERS detection of molecules were based on detection schemes that utilized either DNA aptamers and Raman reporter molecules 28,29,36,37,51–53 or certain kinds of chemical interactions 54–56 , but the availability of suitable aptamers and chemical reactions could limit the use of the nanostructures for the detection of other molecules. Some of the SERS substrates formed with core-satellite nanostructures did not have many SERS hot spots in the z-direction, and the density of the nanostructures in the xy-plane was not maximized 14,27,57 . In this study, we did not use any specific aptamer, Raman reporter, or chemical reactions for SERS detection.…”

“Zero-transfer” production of large-scale, flexible nanostructured film at water surface for surface enhancement Raman spectroscopy

“…2,[6][7][8] In past, the majority of micro-patterning techniques relied on first provision of a hard template such as glass 9 and silicon wafer, 10 wherein a precise machining process, including electron beam lithography, 11 focused ion beam patterning, 12 or vacuum deposition, 13 was generally utilized. These techniques are unaffordable for immediate off-the-shelf of SERS active substrates, 14 due to high capital investment and intensive energy consumption.…”