researches are required to better track the rate and extent of CNPs transformations
under realistic conditions, especially for illustrating the co-occurred multiple transformations. Completely understanding the diverse transformations of CNPs in the
environment requires the ability to recover the products from environmental or
biological matrices. Then, measuring the properties of these partially transformed
CNPs or characterizing them in vivo/in situ is necessary. Additionally, scarcely any
information is presently known about the toxicology under the relevant conditions
regarding long-term exposure to low CNPs doses, which is necessary for better
revealing the current effects of CNPs on the environment.
6.2 Identifying the Toxicological Risk Factors of CNPs
It has been widely known that ROS generation is closely related to the inhibition
effects of CNPs (Park et al. 2008b; Rogers et al. 2010; von Moos and Slaveykova
2014; Xu et al. 2018). However, the information about the quantitative relationships
between ROS formation and the toxicity effects of CNPs for rapid toxicological
screening prior to in vivo testing is lacking. On the other hand, the possibility of
changes in CNPs reactivity and biological molecules after their contacts has been
examined (Li et al. 2014; Rollin-Genetet et al. 2015); thus further studies on kinetics
and biochemical interactions of CNPs within organisms are imperative. These
studies should include research on CNPs transformation pathways, interactions
with cells, the receptors and signaling pathways involved, cytotoxicity, and surface
functionalization for an effective cellular phagocytosis or internalization. Then,
sufficient information to identify the toxicological risk factors including
genotoxicity, induction of cell transformation, and also how the various physicochemical properties or biochemical reactions affect CNPs toxicity is critical. In order
to clarify the risk factors mentioned above, nanoscale characterization techniques
should be introduced to a larger extent to identify CNPs at intracellular sites in
affected cells or tissues and to further establish the pertinent interaction mechanisms.
6.3 Characterizing and Identifying the Potentially Safe
Applications of CNPs in the Future
Another important research topic to be pursued is to reduce the toxicological profiles
of CNPs and maintain the functional properties of the core materials. According to
the existing data discussed above, the anti- and prooxidant activity of CNPs depends
on their physicochemical properties, reactive activity, and extent of cellular internalization. Thus, to avoid the environmental toxicity of CNPs, surface modification
and configuration should be considered in the synthesis process to hinder the
interactions between CNPs with biomolecules and other chemicals within
Surface Properties and Environmental Transformations Controlling the. . .
195
under realistic conditions, especially for illustrating the co-occurred multiple transformations. Completely understanding the diverse transformations of CNPs in the
environment requires the ability to recover the products from environmental or
biological matrices. Then, measuring the properties of these partially transformed
CNPs or characterizing them in vivo/in situ is necessary. Additionally, scarcely any
information is presently known about the toxicology under the relevant conditions
regarding long-term exposure to low CNPs doses, which is necessary for better
revealing the current effects of CNPs on the environment.
6.2 Identifying the Toxicological Risk Factors of CNPs
It has been widely known that ROS generation is closely related to the inhibition
effects of CNPs (Park et al. 2008b; Rogers et al. 2010; von Moos and Slaveykova
2014; Xu et al. 2018). However, the information about the quantitative relationships
between ROS formation and the toxicity effects of CNPs for rapid toxicological
screening prior to in vivo testing is lacking. On the other hand, the possibility of
changes in CNPs reactivity and biological molecules after their contacts has been
examined (Li et al. 2014; Rollin-Genetet et al. 2015); thus further studies on kinetics
and biochemical interactions of CNPs within organisms are imperative. These
studies should include research on CNPs transformation pathways, interactions
with cells, the receptors and signaling pathways involved, cytotoxicity, and surface
functionalization for an effective cellular phagocytosis or internalization. Then,
sufficient information to identify the toxicological risk factors including
genotoxicity, induction of cell transformation, and also how the various physicochemical properties or biochemical reactions affect CNPs toxicity is critical. In order
to clarify the risk factors mentioned above, nanoscale characterization techniques
should be introduced to a larger extent to identify CNPs at intracellular sites in
affected cells or tissues and to further establish the pertinent interaction mechanisms.
6.3 Characterizing and Identifying the Potentially Safe
Applications of CNPs in the Future
Another important research topic to be pursued is to reduce the toxicological profiles
of CNPs and maintain the functional properties of the core materials. According to
the existing data discussed above, the anti- and prooxidant activity of CNPs depends
on their physicochemical properties, reactive activity, and extent of cellular internalization. Thus, to avoid the environmental toxicity of CNPs, surface modification
and configuration should be considered in the synthesis process to hinder the
interactions between CNPs with biomolecules and other chemicals within
Surface Properties and Environmental Transformations Controlling the. . .
195