Characterization of gold nanoparticle uptake by tomato plants using enzymatic extraction followed by single-particle inductively coupled plasma-mass spectrometry analysis.

Plant uptake and accumulation of nanoparticles (NPs) represent an important pathway for potential human expose to NPs. Consequently, it is imperative to understand the uptake of accumulation of NPs in plant tissues and their unique physical and chemical properties within plant tissues. Current technologies are limited in revealing the unique characteristics of NPs after they enter plant tissues. An enzymatic digestion method, followed by single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) analysis, was developed for simultaneous determination of gold NP (AuNP) size, size distribution, particle concentration, and dissolved Au concentration in tomato plant tissues. The experimental results showed that Macerozyme R-10 enzyme was capable of extracting AuNPs from tomato plants without causing dissolution or aggregation of AuNPs. The detection limit for quantification of AuNP size was 20 nm, and the AuNP particle concentration detection limit was 1000 NPs/mL. The particle concentration recoveries of spiked AuNPs were high (79-96%) in quality control samples. The developed SP-ICP-MS method was able to accurately measure AuNP size, size distribution, and particle concentration in the plant matrix. The dosing study indicated that tomato can uptake AuNPs as intact particles without alternating the AuNP properties.