Effects, uptake, and translocation of aluminum oxide nanoparticles in lettuce: A comparison study to phytotoxic aluminum ions

Katie L Hayes; Julie Mui; Boyoung Song; Ehsan Shirzaei Sani; Sasha W Eisenman; Joel B Sheffield; Bojeong Kim

doi:10.1016/j.scitotenv.2020.137393

Effects, uptake, and translocation of aluminum oxide nanoparticles in lettuce: A comparison study to phytotoxic aluminum ions

Sci Total Environ. 2020 Jun 1:719:137393. doi: 10.1016/j.scitotenv.2020.137393. Epub 2020 Feb 19.

Authors

Katie L Hayes¹, Julie Mui¹, Boyoung Song¹, Ehsan Shirzaei Sani², Sasha W Eisenman³, Joel B Sheffield⁴, Bojeong Kim⁵

Affiliations

¹ Department of Earth and Environmental Science, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122, USA.
² Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 7514 Boelter Hall, Los Angeles, CA 90095, USA.
³ Department of Architecture and Environmental Design, Temple University, 580 Meetinghouse Road, Ambler, PA 19002, USA.
⁴ Department of Biology, Temple University, 1900 N. 12th Street, Philadelphia, PA 19122, USA.
⁵ Department of Earth and Environmental Science, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122, USA. Electronic address: bkim@temple.edu.

PMID: 32145490
DOI: 10.1016/j.scitotenv.2020.137393

Abstract

The widespread use of aluminum oxide nanoparticles (Al₂O₃ NPs) unavoidably causes the release of NPs into the environment, potentially having unforeseen consequences for biological processes. Due to the well-known issue of Al phytoxicity, plant interactions with Al₂O₃ NPs are cause for concern, but these interactions remain poorly understood. This study investigated the effects of Al₂O₃ NPs on lettuce (Lactuca sativa L.) to elucidate the similarities and differences in plant growth responses when compared to those of Al ions. Seed germination, root length, biomass production, and uptake of Al and nutrients were measured from hydroponically-grown lettuce with varying concentrations of Al₂O₃ NPs (0, 0.4, 1, and 2 mg/mL) or AlCl₃ (0, 0.04, 0.4, and 1 mg/mL). The Al₂O₃ NPs treatments had a positive influence on root elongation, whereas AlCl₃ significantly reduced emerging root lengths. While 0.4 mg/mL Al₂O₃ NPs promoted biomass, 1 and 2 mg/mL showed a 10.4% and 17.9% decrease in biomass, respectively, when compared to the control. Similarly, 0.4 and 1 mg/mL AlCl₃ reduced biomass to 22.3% and 9.96%, respectively. Both treatments increased Al uptake by roots linearly; however, translocation of Al₂O₃ NPs into shoots was limited, whereas translocation of AlCl₃ increased with increasing treatment concentration. Further, Al₂O₃ NPs adsorbed on the roots serve as adsorbents for macronutrients, promoting their absorption and uptake in plants, but not micronutrients. Calcium uptake was the most inhibited by AlCl₃. A new in vivo imaging technique, with elemental analysis, confirmed that Al₂O₃ NPs were assimilated as particles, not ions, suggesting that the observed phytotoxicity is not due to Al ions being released from the NPs. Thus, it is concluded that Al₂O₃ NPs pose less phytoxicity than AlCl₃, primarily due to NPs role on stimulated root growth, significant adsorption/aggregation on roots, limited lateral translocation to shoots, and increased uptake of macronutrients.

Keywords: Aluminum oxide; Confocal laser scanning microscopy; Nanoparticles; Phytotoxicity; TRITC; in vivo imaging.

MeSH terms

Aluminum
Aluminum Oxide
Cations
Lactuca
Metal Nanoparticles*
Plant Roots

Substances

Cations
Aluminum
Aluminum Oxide