Highly sensitive plasmonic metal nanoparticle-based sensors for the detection of organophosphorus pesticides

• Published in: Talanta (Oxford) 2019-08, Vol.200, p.218-227
• Main Authors: Dissanayake, Niluka M., Arachchilage, Jaliya S., Samuels, Tova A., Obare, Sherine O.
• Format: Article
• Language: English
• Subjects: Bimetallic nanoparticles; Localized surface plasmon resonance; Organophosphorus pesticides; Plasmonic nanoparticles; Sensors
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2019.03.042

Plasmonic nanoparticles offer attractive benefits for the detection of environmental contaminants due to their high extinction coefficients and unique optical properties. Excess use of OP pesticides has been found to have adverse effects on human health and the environment. Here, we demonstrate the use of plasmonic silver (Ag), gold (Au) and bimetallic silver-gold (Ag-Au) nanoparticles (NPs) to detect and distinguish between organophosphorus (OP) pesticides. The NPs were found to detect the thion pesticides: ethion, parathion, malathion, and fenthion) in real time. In each case, the interaction of the pesticides with the plasmonic NPs were found to result in wavelength shifts of the localized surface plasmon resonance (LSPR) accompanied by color changes. The wavelength shifts were characteristic of the pesticide structure and concentration. The interaction between the sensors and the pesticide was a result of the soft metal surface binding to the soft sulfur atom of the pesticide. Similarly, oxon pesticides showed no effect on the LSPR of the NPs. The three plasmonic NPs showed limits of detections (LOD) in ppm range for all pesticides under real-time analysis. The LOD of Ag NPs with ethion, fenthion, malathion, and parathion were 9 ppm, 11 ppm, 18 ppm, and 44 ppm, respectively. The LOD of Au NPs with ethion, fenthion, malathion, parathion were 58 ppm, 53 ppm, 139 ppm, and 3203 ppm, respectively. Ag-Au NPs with ethion, fenthion, malathion, and parathion showed LOD values of 228 ppm, 231 ppm, 1189 ppm, and 1835 ppm, respectively. The ability of the plasmonic NPs to detect the selected pesticides in natural environments was tested under simulated natural conditions in the presence of dissolved organic matter (DOM). Steep gradients in the sedimentation plots revealed that the time dependent interaction of each OP pesticide with the NP surface was accompanied by a considerable change in the LSPR indicative of colloidal destabilization over time. All pesticides showed nearly the same trend in their sedimentation with the plasmonic NPs. The stability of the nanoparticles in the colloidal medium was described by classical DLVO theory, which showed that the net interaction was attractive. [Display omitted] •The plasmonic nanoparticles can detect five OP pesticides (ethion, fenthion, malathion, parathion & paraoxon-ethyl).•Each sensor can differentiate between the five OP pesticides and the detection is visible to the naked eye.•The detection can be monitored by ch