Glutathione-responsive carboxymethyl chitosan nanoparticles cross-linked with disulfide bonds were developed for controlled release of herbicides. The nanoparticles were synthesized by selfassembly 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 preemergence treatment of target species (Echinochloa crusgalli) showed the effectiveness of diuron- loaded nanoparticles. Assays with nontarget species (Zea mays) showed that the diuronloaded nanoparticles did not affect plant growth. The results indicate that the glutathioneresponsive nanoparticles prepared in this work will be a promising candidate for controlled release of herbicides in agriculture.
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