Development of carrier-free self-assembled nanoparticles based on fenhexamid and polyhexamethylene biguanide for sustainable plant disease management

Abstract

The utilization of nanotechnology for the design of pesticide formulations has enormous potential to enhance the efficiency of pesticides and reduce their adverse impacts on the environment. However, the complicated fabrication process of nanosized carriers and their multi-step chemical modifications greatly restrict the practical applications of nanocarrier-based formulations. To address these issues, herein, self-assembled nanoparticles (NPs) based on fungicide fenhexamid (FHA) and polyhexamethylene biguanide (PHMB) were constructed by the electrostatic and hydrophobic interactions between FHA and PHMB in water solution without using carriers or adjuvants. The optimal temperature and mass ratio between FHA and PHMB for the formation of NPs were 60 °C and 10 : 7, respectively. Obtained spherical NPs with sizes of 50–250 nm were stable in neutral and acidic aqueous mediums and displayed desirable physicochemical properties (strong surface positive charges, low conductivity, high light stability, and good surface activity). Moreover, the combination of FHA and PHMB by the self-assembly of NPs had a synergistic effect on the antimicrobial activity, and NPs exhibited higher activities against Pseudomonas syringae pv. lachrymans, Botrytis cinerea, and Sclerotinia sclerotiorum than FHA and PHMB. Furthermore, the results of the genotoxicity evaluation in Vicia faba showed that the prepared NPs did not further increase the cytotoxicity of FHA. Overall, the formation of co-self-assembly nanoparticles of FHA and PHMB via a simple and green approach may be a novel avenue for sustainable plant disease management and provides inspiration to construct new nano-based pesticide formulations.