Graphene oxide/zein nanocomposites loaded with rotenone: Synergistically enhancing the pesticidal activity and biosafety of rotenone

Nanomaterials have been widely applied as pesticide carriers, representing an important approach to enhancing insecticidal efficacy against target pests, improving safety for non-target organisms, and further mitigating environmental pollution. In this work, a pesticide delivery system (SGO-Rot@Zein) was developed by loading rotenone (Rot) onto small-sized graphene oxide (SGO) and further encapsulating with zein as a protective matrix. Characterizations via SEM, FTIR, and TGA confirmed successful synthesis: Rot interacts with SGO through hydrogen bonds and π-π interactions, and zein encapsulates SGO-Rot via hydrogen bonding to enhance thermal stability. Compared with technical Rot, under environmental temperatures (25–35°C) and pH conditions (6.0–8.0), SGO-Rot@Zein exhibited excellent temperature- and pH-responsive controlled release behavior. The release of Rot from SGO-Rot@Zein fitted the Higuchi model (diffusion-controlled release). SGO-Rot@Zein showed significantly improved UV stability (only 69.73 % photodegradation after 168 h vs. 100 % after 96 h for technical Rot) and enhanced wettability on leaf surfaces (smaller contact angles), boosting adhesivity. Biological activity assays demonstrated that SGO-Rot@Zein exerted higher and more persistent insecticidal activity against Rhopalosiphum maidis and Tetranychus urticae than technical Rot, maintaining superior mortality rates up to 14 days post-treatment. Environmental safety evaluations revealed reduced soil mobility and lower acute toxicity to zebrafish. Therefore, SGO-Rot@Zein provides a novel strategy for effective and sustainable pest control with broad application prospects. • Hydrogen bonding and π-π interactions in nanoparticles boost their thermal stability. • SGO-Rot@Zein exhibits temperature- and pH-responsive controlled release behavior. • Nanoparticles show UV stability and enhanced wettability on leaf surfaces. • SGO-Rot@Zein exerts higher and more persistent insecticidal activity. • Nanoparticles revealed reduce soil mobility and lower toxicity to zebrafish.