Carboxymethyl Chitosan-Modified Graphene Oxide as a Multifunctional Vector for Deltamethrin Delivery and pH-Responsive Controlled Release, Enhanced Leaf Affinity, and Improved Mosquito-Killing Activity

Traditional deltamethrin (DM) formulations (e.g., emulsifiable concentrates, wettable powders, etc.) have significant disadvantages of poor water dispersion stability, burst release, weak leaf affinity, short duration, poor efficacy, and high environmental toxicity. A nanomaterial-based pesticide delivery system (PDS) has provided effective strategies for green preparation and synergism of pesticide formulations. In this article, we developed carboxymethyl chitosan (CMCS)-modified graphene oxide (GO) as a vector for DM and constructed a pH-responsive PDS for Culex pipiens pallens control. GO-CMCS possesses excellent pesticide loading performance for DM (loading rate 87.76%). After being loading on GO-CMCS, the GO-CMCS-DM has a significantly improved dispersion stability in water. The GO-CMCS-DM exhibits pH-responsive controlled release performance, which can sustain the release of DM into the medium, maintaining an effective long-term concentration. Additionally, the leaf adhesion of GO-CMCS-DM is better than that for free DM, which can improve the pesticide utilization. Therefore, GO-CMCS-DM has a prolonged persistent period and sustained activity against Culex pipiens pallens. Considering the industrialization potential of GO, we believe that GO will play an important role in the pest control and antiepidemic fields.