Nonselective uptake of silver and gold nanoparticles by wheat

Abstract

Metallic nanoparticles (NPs) show unique reactivity to crop plants, but the uptake mechanisms remain unclear. We quantitatively evaluated the phytoavailability of particles to wheat (Triticum aestivum L.) in hydroponics upon exposure to AgNPs (15 nm) or AuNPs (13 and 33 nm). Particles were physically separated from the released Ag ions by a dialysis membrane, under which particle-specific uptake of AgNPs could be discerned. Plants did not differentiate AgNPs and AuNPs during particle uptake, with uptake rate constants of 1.1 ± 0.1, 1.2 ± 0.3, and 1.2 ± 0.1 L kg⁻¹ h⁻¹ for AgNPs, AuNPs (13 nm), and AuNPs (33 nm), respectively. We found little effect of particle size (13 or 33 nm AuNPs) or core composition (Ag or Au) on particle bioavailability. Plants stimulated the subsequent uptake of Evans blue stain and showed cell damage in root tips. These results imply similar physiological processes involved in particle-specific uptake of AgNPs and AuNPs. The internalization of particles was further confirmed by single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscope-energy dispersive spectrometer (TEM-EDS) analysis. The work here builds the knowledge base for the nature of particle-specific uptake of different NP types by crop plants.

Keywords:

• Metallic nanoparticles
• uptake rate constants
• root damage
• spICP-MS

Acknowledgements

We thank the two anonymous reviewers for their helpful comments on this work. We also thank Prof. Luis M. Nunes, University of Algarve, Portugal, for his help on statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Science Foundation of Jiangsu Province [BK20170110] and the National Natural Science Foundation of China [41430752 and 41671484].