Single particle ICP-MS method development for the determination of plant uptake and accumulation of CeO2 nanoparticles

Abstract

Cerium dioxide nanoparticles (CeO2NPs) are among the most broadly used engineered nanoparticles that will be increasingly released into the environment. Thus, understanding their uptake, transportation, and transformation in plants, especially food crops, is critical because it represents a potential pathway for human consumption. One of the primary challenges for the endeavor is the inadequacy of current analytical methodologies to characterize and quantify the nanomaterial in complex biological samples at environmentally relevant concentrations. Herein, a method was developed using single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) technology to simultaneously detect the size and size distribution of particulate Ce, particle concentration, and dissolved cerium in the shoots of four plant species including cucumber, tomato, soybean, and pumpkin. An enzymatic digestion method with Macerozyme R-10 enzyme previously used for gold nanoparticle extraction from the tomato plant was adapted successfully for CeO2NP extraction from all four plant species. This study is the first to report and demonstrate the presence of dissolved cerium in plant seedling shoots exposed to CeO2NPs hydroponically. The extent of plant uptake and accumulation appears to be dependent on the plant species, requiring further systematic investigation of the mechanisms.

Elucidating the mechanisms for plant uptake and in-planta speciation of cerium in radish (Raphanus sativus L.) treated with cerium oxide nanoparticles

“…The concentrations of total Ce in all treated radish tissues were significantly higher than the concentrations of dissolved Ce in the corresponding tissues, implying the existence of undissolved Ce within plant tissues. Dan et al [14] detected particulate Ce signals in plant tissues spiked with dissolved Ce only using the same enzymatic extraction method adopted in this study. The authors attributed it to the attachment of dissolved Ce on the undigested plant tissue colloids so that the SP (single particle)-ICP-MS mistakenly reported this adsorbed Ce as particulate Ce.…”

“…A few previous studies reported that Ce in plant tissues remained as CeO 2 NPs after plant uptake [11,12]. However, several recent publications suggest that Ce accumulated in plant tissues following plant treatment with CeO 2 NPs could exist in the form of Ce salts [13] or dissolved Ce [14]. Due to the importance of the physicochemical states of Ce to its food safety implications, it is important to further understand the physicochemical properties of Ce in plant tissues after plant exposure to CeO 2 NPs.…”

“…Because CePO 4 and Ce carboxylates were detected in lettuce roots but not in soil, the authors interpreted the results as evidence of in-planta transformation of CeO 2 NPs. More recently, Dan et al [14] investigated the uptake of CeO 2 NPs by four different plant species using a highly sensitive single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) technology and reported common presence of dissolved Ce in plant tissues. In spite of these new progresses, questions remain concerning the mechanisms for CeO 2 NPs uptake by plant, the location of Ce transformation (e.g.…”

Multiple Method Analysis of TiO2 Nanoparticle Uptake in Rice (Oryza sativa L.) Plants

“…This technique has been recently used to analyze the size distribution of gold NPs and cerium dioxide NPs in plants. 19, 20 However, to our knowledge, spICP-MS has not yet been used for assessing TiO 2 NPs in any organism, although spICP-MS has been used to quantify titania NPs in other environmentally relevant matrices. 21–23 The spICP-MS technique utilizes time-resolved isotopic analysis with short dwell times to characterize the particle size distribution and particle number concentration in samples.…”

Atomic spectrometry update – a review of advances in environmental analysis

“…The original particle size distribution was preserved when TX-114 with or without 2mM NaCl was used as extractant. Enzymatic digestion with Macerozyme R-10 successfully recovered both CeO2 NPs170 and Pt NPs 171 from plants that had been grown hydroponically in NP-contaminated nutrient.Several improved methods for radionuclides were reported. Researchers in Japan 172 recommended CaF2/LaF3 co-precipitation followed by sequential application of three commercial resins -TEVA, UTEVA, DGA -for removal of interfering elements in their method for determination of Pu in soils and sediments by SF-ICP-MS. Members of the same team developed a method 173 for ultratrace determination of 241 Am in soil and made a detailed study 174 of TRU and DGA resins for interference removal.…”