This work focused on designing a novel redox-responsive nanocarrier synthesized from carboxymethyl-β-cyclodextrin-modified nanosilica, which could load and release plant hormones, such as salicylic acid (SA), in plant cells. When the SA-loaded nanoparticles cross the plant cell wall, the disulfide bond can be broken to form sulfhydryl groups under the action of reduced glutathione (GSH), thus releasing SA. Meanwhile, the resulting thiol groups exhibited strong affinity toward several heavy metal ions, mercury ions in particular, thus playing a role similar to phytochelatins for detoxification. The results of SA release in vitro proved that the release proceeded much faster in GSH-rich than in GSH-free environments. The adsorption behaviors of the redox-responsive nanoparticles toward heavy metal ions, after phytohormones release, were systematically investigated. Moreover, the synergetic effects on sustained release and metal ion capture enable the redox-responsive cyclodextrin-modified silica to be an effective and dual-functional nanocarrier that has great potential for agricultural applications.
Keywords: carboxymethyl-β-cyclodextrin; heavy metal; nanosilica; phytohormone; redox-responsive.