Application of Anisotropic Gold Nanomaterials in Plasmonic Sensors for Detection of Glyphosate

Abstract

The trend of using agrochemicals is increasing, especially glyphosate-based herbicides (GBH). The application of toxic chemicals as pest control in food crops carries a risk to human safety. Therefore, it is important to create a sensor for detection through Localized Surface Plasmon Resonance (LSPR) by utilizing anisotropic gold nanoparticles (AGN) to detect the presence of GBH contaminants in the form of malathion and temephos, with a detection level as low as three-part per million (ppm). AGN-based LSPR is successfully synthesized through an experimental technique using the Seed Mediated Growth Method (SMGM). The UV-Vis response showed two strong absorbances with a peak occurring around 500 to 600 nm, the peak within the transverse surface plasmon resonance range (t-SPR) corresponds to one aspect, while the peak within the spectral range extending from 700 nm to 900 nm corresponds to another aspect, namely Longitudinal Surface Plasmon Resonance (l-SPR). Anlysis of the FESEM photograph shows a structure consisting of two particles with different shapes, pentagonal pyramids and a bone shape. Pentagonal pyramids joined with a surface density of 64.43 ± 1,53 % and bone shape of 32,46 ± 1.53 %. This characterization shows strong and distinctive optical resonance in the near-infrared visible light spectrum, which is very suitable for LSPR sensors. It is necessary to fabricate an LSPR sensor device capable of detecting the presence of GBH by testing sensitivity, stability and repeatability. The sensitivity test results were evaluated by varying the synthesis time and concentration of contaminants in the AGN growth solution. It confirmed that the AGN-based LSPR sensor has a promising potential for GBH residue detection.