Self-assembled chitosan-based nanocarriers in response to chitinase and plant surface charge: targeted delivery and...

The plants could secrete chitinase and trigger their immune response for disease resistance when they were invaded by pathogenic fungi. On the other side, plant vascular bundle serves as a critical site for pathogen spread and orchestrating immune responses. The targeted delivery of pesticides from the tissue interface to the vascular system could enhance the agrochemical utilization efficiency. In this study, based on the structural and immune characteristics of the plant, a dual-responsive chitosan-based nanocarrier was designed with tailored surface charges and efficient release in response to plant surface charge and chitodextrinase. Tebu@HACC/CS and Tebu@SCS NPs were fabricated to study their bioactivity, and their absorption process was visually tracked by preparing fluorescence-labeled Tebu. As we proposed, the prepared nanopesticide system exhibited dual responsiveness to chitinase and surface charge. The quaternized chitosan nanoparticles with positive charge (HACC/CS NPs) demonstrated absorption absorption-promoting effect in xylem compared with SCS NPs. Upon introduction of chitinase, the cumulative release of HACC/CS and SCS NPs was significantly increased at 130 h, reaching 94.52 % and 91.61 %, respectively. In vivo and in vitro fungal inhibition tests showed that Tebu@HACC/CS NPs exhibited superior fungal inhibition activities. To track pesticide delivery, Rhodamine B-labeled tebuconazole (RBTebu) was synthesized and loaded, and confocal laser scanning microscopy (CLSM) revealed that RBTebu could be efficiently absorbed by the xylem of cotton roots, which indicated that HACC could efficiently enhance transmission and release of the pesticide. These results suggest that Tebu@HACC/CS could be a promising nanopesticide carrier in response to plant structural and metabolic characteristics.