Uptake, distribution and translocation of imidacloprid-loaded fluorescence double hollow shell mesoporous silica nanoparticles and metabolism of imidacloprid in pakchoi

Fluorescent labeling techniques have been increasingly used to study the transport of pesticides in crops instead of radioisotope techniques due to the high cost, low resolution and handling and disposal of radioisotope materials. Nevertheless, the use of fluorescent labeling techniques to study the uptake and translocation mechanisms of pesticides in crops has rarely been reported. The distribution, translocation and metabolism of imidacloprid in the vegetable pakchoi were studied via a combination of fluorescence microscopy and UPLC-MS/MS. The translocation rate of imidacloprid-loaded fluorescence double hollow shell mesoporous silica nanoparticles ([email protected]) under sunlight conditions were observed by fluorescence microscopy to be higher than that under the dark. The [email protected] was mainly transported from the ducts to the stem and leaf parts through transpiration under hydroponic conditions. In contrast, [email protected] was transported downward mainly through the sieve tubes of the phloem driven by photosynthesis after the foliar spray. Moreover, fewer metabolites of imidacloprid from [email protected] were produced than those from 70% Im granules. This work revealed how [email protected] was absorbed, distributed and translocated as well as how the released imidacloprid was metabolized in pakchoi plants.