Enhancement of Single Molecule Raman Scattering using Sprouted Potato Shaped Bimetallic Nanoparticles

Abstract

Herein, for the first time, we report the single molecule surface enhanced resonance Raman scattering (SERRS) and surface enhanced Raman scattering (SERS) spectra with high signal to noise ratio (S/N) using plasmon-active substrates fabricated by sprouted potato shaped Au-Ag bimetallic nanoparticles, prepared using a new one-step synthesis method. This particular shape of the nanoparticles has been obtained by fixing the amount of Au and carefully adjusting the amount of Ag. These nanoparticles have been characterized using scanning electron microscopy, extinction spectroscopy, and glancing angle X-ray diffraction. The single molecule sensitivity of SERS substrates has been tested with two different molecular Raman probes. The origin of the electromagnetic enhancement of single molecule Raman scattering in the presence of sprouted shape nanoparticles has been explained using quasi-static theory as well as finite element method (FEM) simulations. Moreover, the role of (i) methods for binding Raman probe molecules to the substrate, (ii) concentration of molecules, and (iii) Au-Ag ratio on the spectra of molecules has been studied in detail.

Biosensing Using SERS Active Gold Nanostructures

“…In metal nanoparticle suspensions for SERS sensing applications, it is important to control the nanoparticle aggregation and distribution. The colloidal nanoparticle solution can be directly spotted on a glass slide followed by evaporation of the solution (dropcasting) [61,62] (Figure 2a). This method is easy and fast but without specific control of the nanoparticle distributions and signal reproducibility.…”

Latest Novelties on Plasmonic and Non-Plasmonic Nanomaterials for SERS Sensing

“…The shape of these Au/Ag nanoparticles was obtained by carefully setting the quantity of silver for a given quantity of gold. Thus, the authors obtained a LOD of 1 fM for methylene blue molecules [ 80 ]. Joseph et al reported on the fabrication AuAg@Ag hollow cubic nanosystems for a detection of mercaptothiophenol (4-MPh) molecules.…”

Application of Novel Plasmonic Nanomaterials on SERS

“…The peak at 1640 cm −1 was due to molecular H 2 O bending vibrations [78]. The features at 2850-2950 cm −1 indicated the presence of sp 3 -hybridized C-H bonds [80]. Features in the 1000-1450 cm −1 region can be assigned to C-N and possibly C-O stretching vibrations [44,50].…”

“…Features in the 1000-1450 cm −1 region can be assigned to C-N and possibly C-O stretching vibrations [44,50]. The sharp peak at 2120 cm −1 was due to terminal C≡N bond stretching within the incompletely condensed carbon nitride matrix [79,80]. The strong Raman peak at 2155 cm −1 confirmed this assignment (Figure 5b), although it is not clear why there should be a 35 cm −1 difference between the IR and Raman data.…”