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Observation of yttrium oxide nanoparticles in cabbage (Brassica oleracea) through dual energy K-edge subtraction imaging

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Young cabbage plants were placed in distilled water containing synthesized yttrium oxide nanoparticles and then imaged by synchrotron dual-energy X-ray micro-tomography using K-edge subtraction. Nanoparticles were taken up by roots but accumulated at the junction of primary and lateral roots, and none were seen in shoots. The authors suggest that root blockage could be an early harmful effect of such particles on plants.

Key numbers

  • Nanoparticle size 64.9 +/- 16.9 nm by electron microscopy (Results, Fig. 1a).
  • Exposure: 0.120 g of nanoparticles dispersed to a final 0.38 L of distilled water, 10 plants per jar, for 22 days, with a water-only control jar (Methods).
  • Voxel-level calculated yttrium oxide concentrations in root ranged from 44.12 to 551.47 mg/cc (Results, Fig. 5b).
  • The text also states root nanoparticle concentration was estimated at 0.82 to 10.18 micrograms/L, a unit that does not match the voxel values above (Results, p. 5).
  • No yttrium oxide nanoparticles were detected in shoots (Results, Fig. 6).
  • About 30% of plants in both exposed and control jars wilted; both groups showed stress after 10 days (Methods).

Methods (brief)

Plants with four true leaves were moved from a hydroponic nutrient system to jars of distilled water with or without nanoparticles and aerated continuously. After 22 days, plants were fixed, dried and imaged above and below the yttrium K-edge at a synchrotron beamline; subtraction images were segmented to map particle distribution and estimate concentration.

Evidence fitness

Supports statements that yttrium oxide nanoparticles in water are retained in cabbage roots with no detectable movement to shoots under these conditions. It does not measure yttrium in edible cabbage by chemical analysis and does not support food occurrence or human exposure statements.

Limitations

Distilled water as substrate stressed both groups, and roughly 30% of plants wilted. The dose was set high by the experimenters. Concentration estimates are image-derived and the two reported units are inconsistent. Imaging detects particles, not dissolved yttrium.

Update history

No substantive edit history is available in this build. The full commit record is available in git.

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