Hakwon Yoon is a Ph.D student in the Division of Environmental Science and Engineering at POSTECH, Korea. He got his B.D degree in Environmental chemistry and Microbiology (double major) from Pusan National University, Korea in 2013. Right now he is working in Prof. Yoon-Seok Chang’s Lab on environmental implication of nanotechnology and emerging contaminants (Persistent organic pollutants (POPs) and Microplastics).
Uptake, distribution and transformation of zerovalent iron nanoparticles in the edible plant
Nanoscale zerovalent iron (nZVI) is the sole engineered nanoparticle which has been invariably utilized as the ideal soil and groundwater remediation for a fairly long period of time. This could lead to an inevitable risk in the environment due to massive exposure raising concerns in achieving safe nano-remediation. Therefore, the primary focus of this research was to examine the uptake, distribution, and biotransformation of nZVI using edible cucumber (Cucumis sativus) plant. Electron microscopy revealed that nZVI penetrated into the cell membrane of the root, and excess iron was translocated into the leaf and re-mineralized in the vacuoles of parenchymal cells. X-ray absorption spectroscopy identified ferric citrate (71%) and (oxyhydr)oxides (29%) as the main transformed products after 21 days and notably, there was no direct evidence of pristine nZVI translocation to the shoot. The 1.8-fold higher expression of CSHA1 gene indicated that the plant-promoted transformation of nZVI was mainly driven by protons released from the root layers. Collectively, current data provide a good basis for two mechanistic pathways taken together for nZVI transformation by cucumber plant: (1) interaction with low molecular weight organic ligands (most likely the hydroxyl-carboxylate-citrate end products), and (2) dissolution-precipitation of the mineral (e.g., (oxyhydr)oxide products due to iron oxophilicity). To the best of our knowledge, this study represents the first report that comprehensively explores the transformation of nZVI in a crop plant. Information obtained from this study may help to garner fundamental clues and enhance our understanding of the nZVI transformation mechanisms – a previously overlooked risk.