Plasmonic Dual‐Gap Nanodumbbells for Label‐Free On‐Particle Raman DNA Assays

Abstract

and the strategy and results shown here for label-free on-particle DNA detection are promising for the development of molecular fingerprint Raman assays with nanoparticles.

A Chemist’s View on Electronic and Steric Effects of Surface Ligands on Plasmonic Metal Nanostructures

“…Such robust Au–DNA interactions can be mimicked by using polymers with distinctive structures. With the anisotropic adsorption of branched polyethylenimine on AuNRs, Au growth can be selectively facilitated on the tips by forming the internal nanogaps (Figure B) . Notably, when a surface ligand (e.g., cyclodextrin) itself can occupy a large portion of the space on surfaces, the internal nanogaps can be uniformly formed .…”

“…With the anisotropic adsorption of branched polyethylenimine on AuNRs, Au growth can be selectively facilitated on the tips by forming the internal nanogaps (Figure 8B). 3 Notably, when a surface ligand (e.g., cyclodextrin) itself can occupy a large portion of the space on surfaces, the internal nanogaps can be uniformly formed. 79 These nanogap particles with a uniform 1 nm intragap are known to generate strong and uniform Raman signals from the Raman dyes inside the nanogap.…”

“…Notably, when a surface ligand (e.g., cyclodextrin) itself can occupy a large portion of the space on surfaces, the internal nanogaps can be uniformly formed . These nanogap particles with a uniform 1 nm intragap are known to generate strong and uniform Raman signals from the Raman dyes inside the nanogap. ,, …”

“…79 These nanogap particles with a uniform 1 nm intragap are known to generate strong and uniform Raman signals from the Raman dyes inside the nanogap. 2,3,79 If such surface−ligand steric hindrance decreases, the unimpeded ligands can fully utilize their functionalities derived from intra-or intermolecular interactions. For example, unmodified DNAs cannot form Au−thiolate bonds, generating relatively weak steric hindrances with a surface.…”

Carbonized polyacrylonitrile array as a sensitive, biocompatible, and durable substrate for surface-enhanced Raman spectroscopy

“…3 In 1977, 4 SERS was described as a Raman enhancement phenomenon that occurs on the surface of precious metals. In recent years, SERS has benefited from developments in optics, laser technology, and nano-devices, and has become one of the most widely used spectroscopic techniques, with applications in areas such as molecular identification 5,6 biological sensing, 7–9 environmental analysis, 10,11 and national security. 12–14…”