Construction of novel amphiphilic chitosan copolymer nanoparticles for chlorpyrifos delivery

Nanoparticles of a novel amphiphilic copolymer of chitosan with poly(lactide) (PLA) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) were generated. The chemical structure of the copolymer was determined using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and thermogravimetric analysis (TGA). Nanoprecipitation or emulsion/solvent evaporation was employed to prepare nanoparticles of this copolymer loaded with a lipophilic organophosphorus pesticide, chlorpyrifos. The nanoparticle size was adjusted to between 100 and 300 nm by varying the copolymer/chlorpyrifos mass ratio in the two nanoparticle preparation methods. The resulting nanoparticles exhibited high chlorpyrifos loading capacity (LC) and sustained release profiles. The nanoparticle size, loading content (LC), and encapsulation efficiency (EE) decreased with increasing mass ratio of copolymer to chlorpyrifos. Chlorpyrifos release was controlled by adjusting the ratio of copolymer to chlorpyrifos. The study showed that these chitosan-co-PLA-DPPE copolymer nanoparticles can be used as carriers for lipophilic pesticide delivery.