Advances and Challenges in Tracking Interactions Between Plants and Metal-Based Nanoparticles

Abstract

Metal-based nanoparticles (MNPs) are increasingly prevalent in the environment due to both natural processes and human activities, leading to direct interactions with plants through soil, water, and air exposure that can have beneficial and detrimental effects on plant growth and health. Understanding the uptake, translocation, and transformation of MNPs in plants is crucial for assessing environmental risks and leveraging nanotechnology in agriculture. However, accurate analysis of MNPs in plant tissues poses significant challenges due to complex plant matrices and the dynamic nature of nanoparticles. This short review summarizes recent advances in analytical methods for determining MNP-plant interactions, focusing on pre-processing and quantitative nanoparticle analysis. It highlights the importance of selecting appropriate extraction and analytical techniques to preserve nanoparticle integrity and accurate quantification. Additionally, recent advances in mass spectrometry, microscopy, and other spectroscopic techniques that improve the characterization of MNPs within plant systems are discussed. Future perspectives highlight the need to develop real-time in situ monitoring techniques and sensitive tools for characterizing nanoparticle biotransformation.

Keywords: biotransformation; extraction; mass spectrometry; metal-based nanoparticles; plant uptake.

Figure 1

LA-ICP-MS imaging for the distribution of MNPs in tomato stems. (a) LA-ICP-MS image of Zn near the phloem and xylem tissues of the petiole connected to a leaf dosed with ZnO@MSN. (b) The area of the LA-ICP-MS scan with the phloem (blue) and xylem (yellow) regions. (c) Overlay of the LA-ICP-MS Zn signal (in red) with the microscopy image (b), the area of the sample that LA-ICP-MS analyzed in (a) is marked in the red square frame of (c). Reprinted with permission from [51]. Copyright 2023 American Chemical Society.

Figure 2

NanoSIMS imaging of the distribution of MNPs in chili plants. NanoSIMS elemental maps (10 µm × 10 µm) of chili (a,b) leaf, (e,f) stem, and (i,j) root tissues after foliar CdS NP exposure obtained using O⁻ beam polarities to map ⁴⁰Ca⁺ and ¹¹⁴Cd⁺. (c,d,g,h,k,l) show the composite (multi) elemental maps of the chili leaf, stem, and root, respectively, showing the relative locations of Cd (red), Ca (blue), and Zn (green). Reprinted with permission from [59]. Copyright 2023 Elsevier.

Figure 3

TEM analysis of the subcellular distribution of MNPs in tobacco leaves. Representative TEM images of N. benthamiana plants 24 h post-infiltration with DNA-functionalized AuNSs with diameters of 5 nm (a), 10 nm (b), 15 nm (c) and 20 nm (d). The images show progressive magnifications from left to right, with the red boxes indicating the magnification areas. Annotations represent the cell wall (cw) and chloroplast (ch). The filled and open arrows indicate NPs associated with a single cell wall or found between cell walls. Scale bars from left to right, 5 µm, 1 µm, 0.2 µm, and 50 nm. Reprinted with permission from [62]. Copyright 2021 Springer Nature.

Figure 4

Combining μ-XRF and XANES techniques for analyzing the distribution and chemical speciation of MNPs in cucumber plants. (a) μ-XRF images of Ce in cucumber roots and leaves after exposure to 1000 mg/L Cs-nCeO₂ and PAA-nCeO₂. The red area of each map corresponds to the maximum concentration of the Ce element. The lateral roots are denoted by the white boxes in the light microscope images. The scale bars for the roots and leaves represent 100 and 500 μm, respectively. Analyses of Ce XANES spectra (b) and the total contents of Ce(III) and Ce(IV) in the roots (g/kg) and shoots (mg/kg) (c) of cucumber exposed to 1000 mg/L Cs-nCeO₂ and PAA-nCeO₂. Reprinted with permission from [78]. Copyright 2019 American Chemical Society.