Preparation and properties of fipronil/β-cyclodextrin derivatives/chitosan nanoparticles

In this study, β-cyclodextrin (β-CD) was modified and fipronil (FP) was used as a model pesticide, the inclusion complex (ICs) of carboxymethyl-β-cyclodextrin (CM-β-CD) and carboxymethyl-hydroxypropyl-β-cyclodextrin (CM-HP-β-CD) was prepared, then IC_S and chitosan (CS) were interacted with each other to form nanoparticles (NPs) via electrostatic interaction, and the NP_S were characterized. At the same time, the solubility of inclusion complex, the storage stability and light stability of nano-microspheres, and the release behavior in vitro were investigated. The results showed that FP formed 1:1 inclusion complexes with CM-β-CD and CM-HP-β-CD, increasing its solubility in water by 102.34 and 76.29 times, respectively. The drug-loaded nano-microspheres have a regular spherical appearance, the particle size distribution is about 200 nm, and the encapsulation efficiency can reach up to 90.42%. After UV irradiation for 48 h, the degradation rate of both nanoparticles was less than 30%, which was significantly lower than that of FP (88.8%). The release profiles showed the NPs provided sustained release of FP, following the Korsmeyer-Peppas model. The NPs also exhibited a higher release rate under alkaline conditions, which could help improve insecticidal efficacy of alkaline insects in the digestive juice.