The performance of plasmonic sensor using gold nanobipyramids and Cu-modified gold nanobipyramids for sensing malathion in <i>Ipomoea aquatica</i>

Abstract Pesticides are widely used in agriculture, particularly on plants that we frequently consume, including malathion, an organophosphate insecticide. The use of hazardous chemicals to control pests in food crops poses risks to human safety. The urgency of this research lies in the need to develop an effective and sensitive detection method for pesticide residues, particularly malathion, in order to ensure food safety. This study proposes to investigate the performance of plasmonic sensor for the detection of pesticides specifically malathion, in Ipomoea aquatica ( I. aquatica ) using two anisotropic shapes of sensing gold nanomaterials, namely gold nanobipyramids (GNBPs) and Cu-modified gold nanopyramids GNBPs. The research employed the seed-mediated growth method to fabricate sensing materials. The seeding process is carried out to obtain nano seeds for GNBPs and Cu-modified GNBPs, while for the growth process, platinum (Pt) was used as a foreign metal ion for GNBPs and copper for Cu-modified GNBPs. The optical UV–vis analysis revealed two significant absorption peaks: one in the range of ∼500–600 nm, transverse surface plasmon resonance (t-SPR), and the second peak in the range of 800–900 nm, related to longitudinal surface plasmon resonance (l-SPR) for GNBPs and ∼700–800 nm for Cu-modified GNBPs. The sensor testing for detecting malathion in I. aquatica was performed to assess the sensitivity, stability, and repeatability of plasmonic sensor-based GNBPs and Cu-modified GNBPs. This sensor has the potential to be further developed for the detection of various other pesticides and applied in real-time food safety monitoring.