Nano-film pesticide for Schistosoma japonicum cercariae: synthesis, characterization, toxicity and insecticidal effect

To improve the efficiency of pesticides, two novel niclosamide derivatives have been synthesized by adding polyethylene glycol groups (PEG) with different lengths to the niclosamide core. The derivatives were characterized by infrared spectroscopy (IR) and magnetic resonance (1H NMR). The results from brewster angle microscopy (BAM) revealed that these two derivatives formed a self-diffusion thin film at the air–water interface. In addition, Langmuir–Blodgett (LB) films on solid substrate have been used to investigate the formation mechanism of the thin film at the air–water interface, combined with atomic force microscopy (AFM). It was suggested that the height of the monolayer at the air–water interface is consistent with the theoretical length of niclosamide derivatives. Further experimental results indicated that these two compounds exhibit relatively low cytotoxicity to HeLa cells, but have higher efficiency to anti-cercariae compared with that of pristine pesticide.