Surface-enhanced Raman scattering of the adsorption of pesticide endosulfan on gold nanoparticles

Abstract

The absorption of pesticide endosulfan on the surface of gold nanoparticles results from the formation of micrometric structures (1-10 μm) with irregular shape because of the aggregation of individual particles. Such aggregation of gold nanoparticles after absorption of pesticide shows a surface-enhanced Raman scattering (SERS) spectrum, whose intensity depends on the concentration of endosulfan. In addition, the discoloration of the colloidal solution and a diminishing of the intensity of the surface plasmon resonance absorption from individual particles were observed by UV-visible spectroscopy. At the same time, a second band between 638 and 700 nm confirms the formation of aggregates of gold nanoparticles as the concentration of endosulfan increases. Finally, we used the SERS intensity of the S-O stretching vibration at 1239 cm(-1) from the SO3 group as a measure of concentration of pesticide endosulfan. This method could be used to estimate the level of pollution in water by endosulfan in a simple and practical form.

Simultaneous In Situ Extraction and Self-Assembly of Plasmonic Colloidal Gold Superparticles for SERS Detection of Organochlorine Pesticides in Water

“…To date, one commonly used strategy is to immerse a fabricated Au film substrate into an OCP ethanol solution for several hours and then take it out; after flushing the substrate or completely evaporating the solvent, a laser beam was directly focused on this substrate to record Raman signals. 14 However, depositing OCPs on the substrate just by gravity and solvent evaporation may cause signal loss of some OCPs and low reproducibility due to the coffee ring effect and weak interaction between OCPs and the substrate. To solve this problem, another strategy is modification of the adsorbing material or linker molecule on a Au/Ag substrate to specifically capture target OCPs.…”

“…Undoubtedly, it is essential to capture OCP molecules close enough to the metal substrate and that they fall in the hotspot area to obtain SERS signals. To date, one commonly used strategy is to immerse a fabricated Au film substrate into an OCP ethanol solution for several hours and then take it out; after flushing the substrate or completely evaporating the solvent, a laser beam was directly focused on this substrate to record Raman signals . However, depositing OCPs on the substrate just by gravity and solvent evaporation may cause signal loss of some OCPs and low reproducibility due to the coffee ring effect and weak interaction between OCPs and the substrate.…”