Detection of molecular vibrations of atrazine by accumulation of silver nanoparticles on flexible glass fiber as a surface-enhanced Raman plasmonic nanosensor

Surface-Enhanced Raman Spectroscopy (SERS) is a sensitive vibration spectroscopy method applied to analyze a variety of analytes, including toxins and pesticides. The SERS method is an accurate method for detecting significantly low concentrations of biomaterials and chemicals. In the present study, in order to detect atrazine pesticide, the glass fiber substrates coated with silver nanoparticles have been used as SERS plasmonic nanosensors. First, silver nanoparticles were prepared by applying a chemical approach named the Tollens' method, and the SERS plasmonic substrates (SPS) were fabricated by depositing the colloidal silver solution on a glass fiber substrate. The SERS plasmonic nanosensors were fabricated by self-assembling the silver nanoparticles and after functionalization of glass fiber substrate using 3-aminopropyl triethoxysilane (APTES). For this purpose, silver nanoparticles were chemically prepared, and their size distribution was determined to be 140–150 nm using dynamic light scattering (DLS). Ultraviolet–visible spectroscopy was applied for the optical characterization of colloids of silver nanoparticles and the prepared substrates. The results indicate the displacement of the plasmonic peak toward longer wavelengths after self-assembly of the nanoparticles. Field emission scanning electron microscopy images indicated the non-uniform distribution of silver nanoparticles on the surface of glass fiber substrates. Atrazine pesticide was employed as an analyte to investigate the performance of SERS plasmonic substrates (SPS). The detection limit of SPS for detecting atrazine pesticide was equal to 10 −12 M, and the average relative standard deviation for ten repeated measurements was obtained to be 4.02%. With reducing the solution concentration to 10 −12 M, the intensity of Raman modes decreased significantly so that only some peaks were clear. Moreover, the quantum mechanics calculation and molecular dynamics simulation were performed to clarify the molecular interactions between atrazine and silver nanoparticles. By increasing the concentration of atrazine, the Lennard-Jones potential was increased following the experimental results of Raman spectroscopy. • Silver nanoparticles (AgNPs) deposited on glass fibers as SERS-active substrates significantly amplify electric fields under laser light emitted to their surface. • The quantum mechanics calculation and molecular dynamics simulation were performed to clarify the molecular interactions between atrazine and silver nanoparticles. • Fast and sensitive detection of Atrazine up to the concentration of 10 −12 M due to the porous structure of silver nanoparticles (AgNPs) on glass fibers as SERS-active substrates.