X - R A Y N A N O P R O B E

S C I E N T I F I C H I G H L I G H T S

8 8 H I G H L I G H T S 2 0 2 2 I

Fig. 79: Top: Virtual cross- section of roots of wheat

exposed to nanoplastics with a smooth (s30) and rough

(r30) morphology, obtained by micro-computed tomography

in phase contrast mode, at ID19. The cell wall density

regimes appear in colour (high in red, medium in green, low

in cyan). Bottom: Tricolour maps obtained by micro-X-ray fluorescence at ID21 showing the distribution of Pd, K and P in cryo-sections of wheat. The

presence of Pd, the tracer of the nanoplastics, is visible in the s30 and r30 treatments.

Fig. 78: Scanning electron microscopy observations of

the root surface for plants in control conditions (C)

and exposed to polystyrene nanoplastics with a smooth

(s30) and rough (r30) morphology. Nanoplastics are agglomerated and associated with exopolymers present on

roots.

of impact were sought by applying a robust statistical treatment on Fourier-transform infrared spectroscopy (FTIR, performed on ID21) and micro X-ray computed tomography (µCT, performed on ID19). µCT evidenced a thickening of the cell wall of the root (Figure 79), which was consistent with an increase in the absorbance of different bands related with carbohydrates and cell wall components (cellulose, pectin and lignin) observed by FTIR. Conversely, a decrease of these bands was observed

in the shoots, suggesting weaker cell walls. These shifts could correspond to a mechanism of defense against the penetration of the nanoplastics inside the plant.

This study provided a proof of concept that metal-doped nanoplastics are smart and handy tools to study the fate of nanoplastics in environmental systems, paving the way for elucidating interactions in more complex systems by using an integrative approach combining classical