Enzyme digestion combined with SP-ICP-MS analysis to characterize the bioaccumulation of gold nanoparticles by mustard and lettuce plants

Plants can absorb and accumulate engineered nanomaterials (ENMs) through water and soil, providing a potential way for nanoparticles to be enriched in humans through the food chain. In this paper, a combination of enzymatic digestion method and SP-ICP-MS analysis was used to quantitatively characterize the enriched AuNPs in mustard and lettuce plants. The results showed that Macerozyme R-10 enzyme can extract AuNPs from plants without obvious aggregation/dissolution. Both mustard and lettuce plants can absorb and enrich the complete AuNPs to the above-ground organs, and the particle number concentrations detected are 1.24 × 107 particles L−1 and 4.39 × 107 particles L−1, respectively. With different exposure level of AuNPs(0.5 mg L−1,), a particle number concentration of 2.32 × 107 particles L−1 was detected in the stems of lettuce plants, while the mustard failed to transport AuNPs to the above-ground organs. The transport efficiency of Au ions by plants is higher than that of AuNPs, and the plants have stronger bioavailability for ions. [Display omitted] •Enzymatic digestion method combined with SP − ICP − MS analysis was adopted for the characterization of AuNPs in plants.•The effects of different exposure levels of AuNPs on plant uptake were investigated.•The absorption and accumulation efficiency of different forms of Au by plants was discussed.