Fast and sensitive detection of carbaryl pesticide trace by using 2D-arrays of Au and Au/Ag core/shell nanoparticles

Thuy Ung Thi Dieu and Liem Nguyen Quang

Abstract

We report on (i) the synthesis of monodisperse Au and Au-core/Ag-shell nanoparticles (NPs) with controllability of the Au-core in the range of 20–50 nm and fixing the thickness of the Ag shell of ~20 nm, and (ii) the arrangement of two-dimensional (2D) arrays of Au core and Au-core/Ag-shell NPs on the 1 cm² ITO substrates. Various Au NPs with uniform size-distribution were synthesised by seed-mediated growth method at ambient conditions. All synthesised 2D-arrays with homogeneous and dense monolayers of NPs (coverage ~85%) were prepared by hybrid deposition method based on the mixed n-alkanethiolate self-assembled monolayer. We have used the fabricated 2D-arrays from the 20-nm Au-core/Ag-shell NPs as a surface-enhanced Raman scattering (SERS) substrate to take the Raman scattering spectra of carbaryl pesticide at very low concentration of 0.01 ppm.