Sensitive Surface-Enhanced Raman Spectroscopy (SERS) Detection of Organochlorine Pesticides by Alkyl Dithiol-Functionalized Metal Nanoparticles-Induced Plasmonic Hot Spots

Abstract

In this work, we report the detection of the organochlorine pesticides aldrin, dieldrin, lindane, and α-endosulfan by using surface-enhanced Raman spectroscopy (SERS) and optimization of the SERS-sensing substrate. In order to overcome the inherent problem of the low affinity of the above pesticides, we have developed a strategy consisting of functionalization of the metal surface with alkyl dithiols in order to achieve two different goals: (i) to induce the nanoparticle linkage and create interparticle junctions where sensitive hot spots needed for SERS enhancement are present, and (ii) to create a specific environment in the nanogaps between silver and gold nanoparticles, making them suitable for the assembly and SERS detection of the analyzed pesticides. Afterward, an optimization of the sensing substrate was performed by varying the experimental conditions: type of metal nanoparticles, molecular linker (aromatic versus aliphatic dithiols and the length of the intermediate chain), surface coverage, laser excitation wavelength. From the adsorption isotherms, it was possible to deduce the corresponding adsorption constant and the limit of detection. The present results confirm the high sensitivity of SERS for the detection of the organochlorine pesticides with a limit of detection reaching 10(-8) M, thus providing a solid basis for the construction of suitable nanosensors for the identification and quantitative analysis of this type of chemical.

Impact of the Crosslinker’s Molecular Structure on the Aggregation of Gold Nanoparticles

“…In terms of electro-optic devices, AuNP could act as plasmonic waveguides [10][11][12][13]. Additionally, films of interlinked AuNP can be used to study the conductance of molecules [5,14,15].…”

Ag Nanoparticles Decorated Cactus-Like Ag Dendrites/Si Nanoneedles as Highly Efficient 3D Surface-Enhanced Raman Scattering Substrates toward Sensitive Sensing

“…[1][2][3][4] It was widely pursued in various fields due to the rich fingerprinting information of analytes at trace levels or even at single-molecule levels. 5,6 However, the biggest obstacle to the expansion of the scope of practical application for SERS sensing is the lack of highly efficient substrates with uniform and high-density hotspots.…”

Structures and Conformations of Alkanedithiols on Gold and Silver Nanoparticles in Water

“…8,9 While it is generally assumed that organodithiols exist as dithiolates on plasmonic gold and silver nanoparticles (AuNPs and AgNPs) that bridges two AuNPs or electrodes as a single molecular linker, 1,2,4,6 conclusions from studies on the organodithiol structure and conformation on AuNPs and AgNPs have been highly controversial. For example, Joo et al proposed that oligomerized dithiols, not dithiol monomers, bridge two plasmonic nanoparticles.…”