Green synthesis of AgNP–ligand complexes and their toxicological effects on Nilaparvata lugens

BACKGROUND: Despite developments in nanotechnology for use in the pharmaceutical field, there is still a need for implementation of this technology in agrochemistry. In this study, silver nanoparticles (AgNPs) were successfully prepared by a facile and an eco-friendly route using two different ligands, 2ʹ-amino-1,1ʹ:4ʹ,1″-terphenyl-3,3″,5,5″-tetracarboxylic acid (H(4)L) and 1,3,6,8-tetrakis (p-benzoic acid)-pyrene (TBAPy), as reducing agents. The physiochemical properties of the as-obtained AgNPs were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The toxicity of H(4)L–AgNP and TBAPy–AgNP against the brown planthopper (BPH, Nilaparvata lugens) was also measured. RESULTS: SEM and TEM analyses demonstrated the formation of quasi-spherical AgNP structures in the presence of H(4)L and TBAPy. Insecticidal assays showed that TBAPy is less effective against N. lugens, with a median lethal concentration (LC(50)) of 810 mg/L, while the toxicity of H(4)L increased and their LC(50) reached 786 mg/L 168 h posttreatment at a high concentration of 2000 mg/L. H(4)L–AgNPs were also highly toxic at a low concentration of 20 mg/L, with LC(50) = ~ 3.9 mg/L 168 h posttreatment, while TBAPy–AgNPs exhibited less toxicity at the same concentration, with LC(50) = ~ 4.6 mg/L. CONCLUSIONS: These results suggest that the synthesized AgNPs using the two ligands may be a safe and cheaper method compared with chemical insecticides for protection of rice plants from pests and has potential as an effective insecticide in the N. lugens pest management program. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12951-021-01068-z.