ROS‐responsive modified chitosan oligosaccharide nanocapsules for improving pesticide efficiency and intelligent release

Some traditional pesticide formulations are inefficient, leading to excessive use and abuse of pesticides, which in turn effects environment. Intelligent release pesticide formulations are ideal for improving pesticide utilization and persistence while reducing environmental pollution.We designed a benzil-modified chitosan oligosaccharide (CO-BZ) to encapsulate avermectin (Ave). Ave@CO-BZ nanocapsules are prepared based on a simple interfacial method via cross-linking of CO-BZ with diphenylmethane diisocyanate (MDI). The Ave@CO-BZ nanocapsules have an average particle size of 100 nm and exhibited a responsive release performance for ROS. The cumulative release rate of nanocapsules at 24 h with ROS increased by about 11.4% compared to that without ROS. The Ave@CO-BZ nanocapsules displayed good photostability. Ave@CO-BZ nanocapsules can penetrate root-knot nematodes more easily and exhibited better nematicidal activity against root-knot nematodes. The pot experiment showed that the control effect of Ave CS at low concentration was 53.31% at the initial stage of application (15 d), while Ave@CO-BZ nanocapsules was 63.54%. Under the same conditions, the control effect of Ave@CO-BZ nanocapsules on root-knot nematodes was 60.00% after 45 days of application, while Ave EC was only 13.33%. The acute toxicity experiments of earthworms showed that the toxicity of nanocapsules was significantly lower than that of EC.The ROS-responsive nanocapsules can improve the utilization of pesticides and non-target biosafety. This modified chitosan oligosaccharide has great potential as a bio stimuli-responsive material, and this simple and convenient method for preparing Ave@CO-BZ nanocapsules provides a direction for the effective utilization of pesticides. © 2023 Society of Chemical Industry.