Zeptomolar detection of 4-aminothiophenol by SERS using silver nanodendrites decorated with gold nanoparticles

In the present work we report a simple, fast, reproducible and cheap methodology for SERS substrate fabrication of silver dendritic nanostructures (prepared by electrodeposition) decorated with gold nanospheres by electrophoretic deposition. This is the first report where a metal dendritic nanostructure has been decorated with another type of metal nanoparticles by this technique. The decorated nanostructures were used directly as SERS substrate using 4-aminothiophenol (4-ATP) as analyte. The objective of the decoration is to create more hot-spots in order to detect the analyte in a lower concentration. Decorated nanodendrites had a detection limit one million times lower than bare silver nanodendrites and all the substrates showed an increase in the Raman intensity at concentrations below 1 nM; because this concentration corresponds to the threshold for the formation of a monolayer resulting in a triple mechanism of intensity increase, namely electric field, chemical factor and hot-spots. 4-ATP was detected in zeptomolar concentration, which is below 1 ppq, corresponding to an analytical enhancement factor (AEF) in the order of 1015.

Fabrication of Silver Nanodendrites on Copper for Detecting Rhodamine 6G in Chili Powder Using Surface-enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is increasingly being used as a method for detecting traces of contaminants in a variety of specimens. In order to maximize SERS’s performance, the most important thing is to have highly active SERS substrates. In this report, we present a simple method for synthesizing silver nanodendrites (AgNDs) on the surface of a copper (Cu) plate using chemical deposition method. The results showed that, after fabrication, a large number of fern-like AgNDs formed on the Cu surface. These AgNDs are distributed evenly across the entire Cu surface with a relatively thick density. The prepared AgNDs were applied as SERS substrates for detecting Rhodamine 6G (R6G) in chili powders. The results showed that, using the prepared AgNDs substrates, as low as 10−10 M R6G in chili powders can be detected. This demonstrates the applicability of fabricated AgNDs as a highly active SERS substrate.

Portable surface-enhanced Raman scattering analysis performed with microelectrode-templated silver nanodendrites

Using a handheld Raman spectrometer, we demonstrate how silver nanodendritic substrates formed using microelectrode platforms and a semi-batch process can be used for ultrasensitive detection and identification of target analytes.