User-safe and efficient chitosan-gated porous carbon nanopesticides and nanoherbicides.

Nanopesticides are selected as one of ten chemical innovations that will change our world. Carboxylated porous carbon nanoparticles (PCNs) were used to encapsulate water-insoluble pesticides and subsequently capped with chitosan (CS) to prepare the CS-gated PCN (PCN@CS) nanopesticides for the controlled release of pesticides in response to acidic pH and elevated temperature with good fungicidal efficacy. To resolve the issue of gastrointestinal absorption of PQ upon ingestion of PQ formulation, it is an innovative strategy to select the carboxylated PCNs as the paraquat (PQ) nanocarriers to inhibit PQ release in the gastrointestinal tract from the origin. The PQ-loaded PCN@CS nanoherbicides showed very low cytotoxicity to human normal cells and high survival rate in mice because the strong π-π interactions between the electron-deficient PQ and the electron-rich PCNs almost inhibited the release of PQ at both acidic and alkaline pH values. The controlled release of PQ from the nanoherbicides was realized at elevated temperatures owing to the weakening of the strong π-π interactions, aiming to eliminate weeds via the photothermal effect of PCNs under natural sunlight. The user-safe PCN-based PQ formulation can inhibit PQ release in the gastrointestinal tract and keep the PQ herbicidal efficacy in the practical application.