influences specific groups such as sulfhydryl and carbonyl
groups, thereby imparting oxidative stress by hindering the
cellular homeostasis. Particle size and surface properties
greatly influence the plant-ENPs interaction. Depending
upon the physical properties of ENPs, these can either act as
nanofertilizers or as phytotoxic agents (Pradhan and Mailapalli 2017). The metal ENPs impart toxic effects in plants
through three mechanisms; first: the ENPs release specific
ions which might be toxic to plants. For instance, Ag
+ ions
released from Ag ENPs transport through the plasma
membrane hinder cellular respiration which ultimately
results in cell death. Second, their chemical interactions with
cellular components may produce chemical radicals to
generate oxidative stress in plants. Thirdly, ENPs can
directly interact with plant cells and disrupt membrane
integrity. Since metal-based ENPs are sparingly soluble,
impart a detrimental effect on plants (Verma et al. 2018).
The outcomes of toxicity are recorded as inhibition in seed
germination, lowered photosynthetic rate, plant growth, and
development, fruit production, followed by reactive oxygen
species (ROS) generation, and hampering in the synthesis of
major biomolecules for cell growth (Pullagurala et al. 2019).
The co-exposure of TiO 2 NPs (0, 100, 250 mg l
−1 ) and Cd
(0, 50 mM) determined that root exposure has shown a more
prominent effect rather than foliar exposure on hydroponic
culture study in maize (Zea mays L.). In addition to this, the
accumulation of TiO 2 was also reported (increased by 1.61
and 4.29 times) upon root exposure and foliar spray of TiO 2
nanoparticles helped in reducing Cd accumulation and further lowering Cd-induced phytotoxicity in maize than
root exposure (Lian et al. 2020).
A similar type of study was also performed to evaluate
the effect of TiO 2 on the phytotoxicity of Cd in Oryza sativa
L. and TiO 2 was found to lower the toxicity and accumulation of Cd in booting and tillering stages of plants (Zhang
et al. 2020). Furthermore, the impact of PbS nanoparticles on
the Zea mays L. was also studied at various hydroponic
treatments and it was concluded that it exerts potential toxicity to plant, seed germination, and root elongation. The
STEM-EDS mapping has suggested the presence of PbS
inside cortical cells, cytoplasm, and intracellular space suggesting its translocation and accumulation (Ullah et al.
2020). In this view, Tripathi et al. (2017) have summarized
the potential mechanism of phytotoxicity, anatomical,
physiological, biochemical, and molecular damages due to
ENPs. They have also pointed out the defense and detoxification mechanism led by plants owing to the accumulation
of ENPs inside plant cells (Tripathi et al. 2017). Another
study has highlighted the Ag NPs-driven changes in photochemical efficiency of Vicia faba through leaves injection
at the concentration of 100 ppm and it has the prominent
repercussion of decreasing photosystem II efficiency and
increases non-photochemical quenching, affecting stomatal
conductance, and assimilation of carbon dioxide (Falco et al.
2020).
7 Monitoring Methods for Engineered
Nanoparticles
The exposure of ENPs results in adsorption, aggregation,
deposition, or accumulation in the soil–plant system, and
thus valid analytical methods are required to monitor their
quantification, traveling, imaging in the ecosystem. To
address the characteristic features of ENPs which mainly
influence their interaction in the environment, the broad
range of methods are available for their recognition and
categorization, jointly with microscopy, spectroscopy,
chromatography, synchrotron radiation-based methods, and
also including dynamic light scattering (DLS), voltammetry,
isotopic methods, size partition, and sensor-based methods.
The shape, morphology, particle size, size distribution,
and aggregation, accumulation can easily be acquired by
using different microscopy-based techniques. For this
scanning/transmission electron microscopy (SEM/TEM),
scanning transmission electron microscopy (STEM), X-ray
fluorescence microscopy (XRF), atomic force microscopy
(AFM), transmission X-ray microscopy (TXM), confocal
laser scanning microscopy (CLSM), and hyperspectral
microscopy are currently available modern spectroscopy
techniques. They can easily imaging the ENPs up to
nanometer size, helps to acquire 2D/3D images, in the
detection limit µg-ng/g without using any external standard
in imaging. Many researchers have previously used these
kinds of imaging techniques to obtain different monographs
of ENPs which are useful to their kinetic investigation,
in vivo toxicity, translocation, accumulation, and particle
behavior (Jampílek and Kráľová 2017). However, these
methods have certain limitations like tedious sample preparation, whole sample representation, geometry, mechanical
tips, and loss of material during staining which counteracts
for inaccuracy in data acquisition.
Furthermore, spectroscopy methods like UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared
(FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDX) are frequently used due to their easy handling,
fast sample preparation, user-friendly, minimum aggregation,
direct analysis, and economically viable. To investigate the
fluorescent-labeled
ENPs
matrix-assisted
laser
desorption/ionization (MALDI), laser-induced fluorescence
(LIF), or iron-trap (IT) mass spectrometry has been previously
conducted (Shrivastava et al. 2019). In this view, the information about the particular nanoparticle, nanoparticle aggregation state, and average particle size, functional
characteristics, and presence of outer coating can be obtained
through these methods. Both NMR and IR spectroscopy were
112
D. Mishra et al.
groups, thereby imparting oxidative stress by hindering the
cellular homeostasis. Particle size and surface properties
greatly influence the plant-ENPs interaction. Depending
upon the physical properties of ENPs, these can either act as
nanofertilizers or as phytotoxic agents (Pradhan and Mailapalli 2017). The metal ENPs impart toxic effects in plants
through three mechanisms; first: the ENPs release specific
ions which might be toxic to plants. For instance, Ag
+ ions
released from Ag ENPs transport through the plasma
membrane hinder cellular respiration which ultimately
results in cell death. Second, their chemical interactions with
cellular components may produce chemical radicals to
generate oxidative stress in plants. Thirdly, ENPs can
directly interact with plant cells and disrupt membrane
integrity. Since metal-based ENPs are sparingly soluble,
impart a detrimental effect on plants (Verma et al. 2018).
The outcomes of toxicity are recorded as inhibition in seed
germination, lowered photosynthetic rate, plant growth, and
development, fruit production, followed by reactive oxygen
species (ROS) generation, and hampering in the synthesis of
major biomolecules for cell growth (Pullagurala et al. 2019).
The co-exposure of TiO 2 NPs (0, 100, 250 mg l
−1 ) and Cd
(0, 50 mM) determined that root exposure has shown a more
prominent effect rather than foliar exposure on hydroponic
culture study in maize (Zea mays L.). In addition to this, the
accumulation of TiO 2 was also reported (increased by 1.61
and 4.29 times) upon root exposure and foliar spray of TiO 2
nanoparticles helped in reducing Cd accumulation and further lowering Cd-induced phytotoxicity in maize than
root exposure (Lian et al. 2020).
A similar type of study was also performed to evaluate
the effect of TiO 2 on the phytotoxicity of Cd in Oryza sativa
L. and TiO 2 was found to lower the toxicity and accumulation of Cd in booting and tillering stages of plants (Zhang
et al. 2020). Furthermore, the impact of PbS nanoparticles on
the Zea mays L. was also studied at various hydroponic
treatments and it was concluded that it exerts potential toxicity to plant, seed germination, and root elongation. The
STEM-EDS mapping has suggested the presence of PbS
inside cortical cells, cytoplasm, and intracellular space suggesting its translocation and accumulation (Ullah et al.
2020). In this view, Tripathi et al. (2017) have summarized
the potential mechanism of phytotoxicity, anatomical,
physiological, biochemical, and molecular damages due to
ENPs. They have also pointed out the defense and detoxification mechanism led by plants owing to the accumulation
of ENPs inside plant cells (Tripathi et al. 2017). Another
study has highlighted the Ag NPs-driven changes in photochemical efficiency of Vicia faba through leaves injection
at the concentration of 100 ppm and it has the prominent
repercussion of decreasing photosystem II efficiency and
increases non-photochemical quenching, affecting stomatal
conductance, and assimilation of carbon dioxide (Falco et al.
2020).
7 Monitoring Methods for Engineered
Nanoparticles
The exposure of ENPs results in adsorption, aggregation,
deposition, or accumulation in the soil–plant system, and
thus valid analytical methods are required to monitor their
quantification, traveling, imaging in the ecosystem. To
address the characteristic features of ENPs which mainly
influence their interaction in the environment, the broad
range of methods are available for their recognition and
categorization, jointly with microscopy, spectroscopy,
chromatography, synchrotron radiation-based methods, and
also including dynamic light scattering (DLS), voltammetry,
isotopic methods, size partition, and sensor-based methods.
The shape, morphology, particle size, size distribution,
and aggregation, accumulation can easily be acquired by
using different microscopy-based techniques. For this
scanning/transmission electron microscopy (SEM/TEM),
scanning transmission electron microscopy (STEM), X-ray
fluorescence microscopy (XRF), atomic force microscopy
(AFM), transmission X-ray microscopy (TXM), confocal
laser scanning microscopy (CLSM), and hyperspectral
microscopy are currently available modern spectroscopy
techniques. They can easily imaging the ENPs up to
nanometer size, helps to acquire 2D/3D images, in the
detection limit µg-ng/g without using any external standard
in imaging. Many researchers have previously used these
kinds of imaging techniques to obtain different monographs
of ENPs which are useful to their kinetic investigation,
in vivo toxicity, translocation, accumulation, and particle
behavior (Jampílek and Kráľová 2017). However, these
methods have certain limitations like tedious sample preparation, whole sample representation, geometry, mechanical
tips, and loss of material during staining which counteracts
for inaccuracy in data acquisition.
Furthermore, spectroscopy methods like UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared
(FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDX) are frequently used due to their easy handling,
fast sample preparation, user-friendly, minimum aggregation,
direct analysis, and economically viable. To investigate the
fluorescent-labeled
ENPs
matrix-assisted
laser
desorption/ionization (MALDI), laser-induced fluorescence
(LIF), or iron-trap (IT) mass spectrometry has been previously
conducted (Shrivastava et al. 2019). In this view, the information about the particular nanoparticle, nanoparticle aggregation state, and average particle size, functional
characteristics, and presence of outer coating can be obtained
through these methods. Both NMR and IR spectroscopy were
112
D. Mishra et al.