Novaluron nanoparticles: Formation and potential use in controlling agricultural insect pests

Nanoparticles of novaluron, a water-insoluble insecticide, were prepared by a novel method, based on a direct conversion of O/W microemulsions containing pesticide and volatile solvents, into powders. The conversion of nanoparticles into powder was achieved by rapid evaporation of all the liquids in the microemulsion by spray drying. The microemulsions were evaluated by SAXS, self diffusion NMR, conductivity, and viscosity. The droplet size was approximately 6. nm, and the novaluron particle size, after redispersion and evaluation by DLS, was 200 ± 50. nm. These particles consisted of aggregates of nanoparticles (30-100. nm), as viewed by Cryo-TEM. Electron diffraction and XRD showed that the nanoparticles were amorphous indicating a possible improved bioactivity. The stability of the dispersed nanoparticles was evaluated by following particle size by DLS for a period of time, revealing a slight increase in particle size despite the high value of zeta potential. In vivo experiments carried out with Egyptian cotton leafworm Spodoptera littoralis larvae indicated that the toxicity of nanoparticles of novaluron resembled that of the commercial formulation.