Mesoporous silica-based pH/enzyme dual-response system: Nanoparticles for smart delivery of indoxacarb with improved insecticidal activity and biocompatibility

Mesoporous silica nanoparticles (MSN) are ideal carriers for agrochemical control release systems due to their smart environmental stimulus response by easy modification. Herein, MSN loaded with indoxacarb (IN) were successfully prepared using the hard template method. Dopamine (DA) and α-cyclohexapentylose (α-CD) were encapsulated around the MSN surface to obtain pH and enzyme dual-response nanoparticles (IN@MSN@PDA@α-CD). The prepared nanoparticles showed a spherical core-shell structure with a loading content of 22.5 %, and the polymer coating covering the surface of the nanoparticles effectively protected IN from photolysis. Moreover, different biostimuli associated with Spodoptera frugiperda can trigger the release of IN from nanoparticles. Compared with the commercial emulsifiable concentrate (14.93 mg L−1), IN@MSN@PDA@α-CD (8.89 mg L−1) extended the effective duration of IN against Spodoptera frugiperda, and considerably decreased the toxicity of IN to Eisenia fetida, zebrafish and human BEAS-2B cells. Thus, pH/enzyme dual-responsive nanoparticles have substantial potential for sustainable on-demand targeted delivery of agrochemicals and for improving their environmental safety.