Highly sensitive gold nanoparticles-modified silver nanorod arrays for determination of methyl viologen.

Abstract

Gold nanoparticles-modified silver nanorod (AuNPs@AgNR) arrays were fabricated as surface-enhanced Raman spectroscopy (SERS) substrates. The coffee ring effect of the AuNPs@AgNR was explored as a preconcentration method for enriching the targetanalytes and increasing the "hot spots." Furthermore, methyl viologen (MV) as a toxic herbicide used in agricultural production was successfully determined to investigate the application of the coffee ring effect on AuNPs@AgNR arrays and density functional theory (DFT) was employed to calculate its vibrational modes of corresponding characteristic peaks. Good linearity was obtained in the range 0.10-100mg/L, and the limit of detection (LOD) of MV was estimated to be 0.01mg/L, which was lower than the US maximum residue limits (MRLs). This method was also applied to practical detection of MV in river water and apple peel with LODs of 0.10mg/L and 0.05mg/L, respectively. SERS results suggest that the coffee ring on AuNPs@AgNR arrays provides a promising way for monitoring environmental pollution and food safety caused by pesticides.