Glutathione-Responsive Carboxymethyl Chitosan Nanoparticles for Controlled Release of Herbicides

Abstract

Glutathione-responsive carboxymethyl chitosan nanoparticles cross-linked with disulfide bonds were developed for controlled release of herbicides. The nanoparticles were synthesized by self-assembly of amphiphilic carboxymethyl chitosan derivative (CMCS-MUA) in aqueous solution and subsequently producing disulfide cross-linking bonds by ultrasonic treatment. TEM showed that the nanoparticles had a spherical core-shell configuration with a size of about 250 nm. Assessment of stability of the nanoparticles (considering mean diameter, polydispersity, and Zeta potential) was conducted over a period of three months, and the nanoparticles were found to be stable in solution. Herbicide-loaded nanoparticles were prepared using diuron as a model herbicide. In vitro release study revealed that diuron can be released from nanoparticles in a controlled manner depended on the glutathione concentration. Herbicidal activity assays performed with pre-emergence treatment of target species (Echinochloa crusgalli) showed the effectiveness of diuron-loaded nanoparticles. Assays with nontarget species (Zea mays) showed that the diuron-loaded nanoparticles did not affect plant growth. The results indicate that the glutathione-responsive nanoparticles prepared in this work will be a promising candidate for controlled release of herbicides in agriculture.