Oligonucleotide-Mediated Au–Ag Core–Shell Nanoparticles

Abstract

The bimetallic core-shell nanoparticles show unique plasmonic properties and their preparations and characterizations are currently under investigation. A new type of Au core-Ag shell (Au@Ag) nanoparticles is prepared by sandwiching the chemically attached Raman reporter molecules (RRMs) and a 12-base-long oligonucleotide between the 13 nm average size core-gold nanoparticles (AuNPs) and 9 nm and 21 nm average size of Ag shell. The synthesized Au@Ag nanoparticles are tested for their surface-enhanced Raman scattering (SERS) performance. It is found that the chemical attachment of the oligonucleotides along with the RRM improved the enhancement in Raman scattering more than one order of the magnitude with the Au@Ag nanoparticles with an average 9-nm shell thickness while the Au@Ag nanoparticles with 21 nm average shell thickness have poor SERS activity. A minimum enhancement factor of 1.0×10 7 is estimated for the SERS active oligonucleotide-mediated Au@Ag nanoparticles. The approach may provide new routes for preparation of highly sensitive new generation of bimetallic core-shell nanoparticles.

Silver-Based Nanoparticles for Surface Plasmon Resonance in Organic Optoelectronics

“…The mixture of Ag and Au NPs has SPR peaks at 400 and 520 nm, which correspond to the plasmonic peak of pure Ag NPs and pure Au NPs, respectively . In contrast, Ag–Au core–shell metal NPs have only one SPR peak at 500 nm with a broad shoulder at 400 nm . This core–shell structure can be used together with the strategy of controlling the shape of metal NCs.…”

“…[ 78 ] In contrast, Ag-Au core-shell metal NPs have only one SPR peak at 500 nm with a broad shoulder at 400 nm. [ 79 ] This core-shell structure can be used together with the strategy of controlling the shape of metal NCs. One example is use of Au-Ag core-shell nanorods (NRs).…”

Preparation and characterization of different shapes of Au–Ag bimetallic nanocomposites for enhanced physicochemical properties

“…The Ag + ions adsorbed on the surface of AuNPs undergo a reduction in the presence of a weak reducing agent, ascorbic acid to form a layer on the surface of existing metallic surfaces. Subsequently, the resultant NCs may lead to the increment of size compared to bare NPs due to the growing thickness of the Ag-shell irrespective of the Au-core size which can be evidenced by the DLS particle size distribution [39]. It was found that the average hydrodynamic size of AuNS (28 nm) changed to 30 nm after coating of 10 l Ag + ions.…”

Fundamentals and applications of SERS-based bioanalytical sensing

“…There are several studies focusing on the development of novel SERS nanotags for the specific detection of biological molecules [150,[160][161][162][163][164][165][166][167][168][169]. Such assays have been developed to target cancer cells [164], other cancer biomarkers [166], and proteins [163].…”

“…The attachment usually involves coated glass or polymer beads, which makes easy surface chemistry for the attachment of different targeting molecules. SERS nanotag assays have been mostly prepared as core-shell NPs such as silver core-glass shell [160], gold core-silica shell [162], or gold core-silver shell [166,167] for use in biosensing [150,168,169].…”