25
negatively charged, or neutral. The sign and magnitude strongly affect the nanomaterial behavior in various media. It has been reported that surface charge and particle
composition of nanoparticles are significant factors of their action and toxicity on
cellular processes (Beddoes et al. 2015). A positively charged material was shown
to penetrate cell membrane more easily than negatively charged or neutral nanoparticles (Georgieva et al. 2011). Also, toxicity of nanomaterials might be determined
by surface charge. In a study carried on zebrafish and mice embryos, positively
charged PAMAM dendrimers were observed to be toxic, while no toxicity effect
was detected for negatively charged PAMAM dendrimers (Heiden et al. 2007). Liu
et al. investigated the surface charge effect on cellular uptake, cytotoxicity, and
in vivo biodistribution of CdSe/ZnS quantum dots. They have demonstrated that
charged particles, especially negatively charged ones, were internalized by macrophage and cancer cells more efficiently than neutral particles. They have also shown
that distribution and cytotoxicity of nanoparticles were strongly dependent on surface charge (Liu et al. 2015). Wang et al. have shown that negatively charged Au
nanoclusters accumulated in liver and spleen took relatively longer time, while positive Au nanoclusters have an adverse effect on the blood system. They also confirmed that surface charge has a significant effect on tumor uptake. Negatively
charged Au nanoclusters exhibited the highest tumor uptake (Wang et al. 2016).
Since surface charge has a profound influence on material–biological system interaction, researchers have been trying to modify and control the surface charge of
materials in order to overcome their toxicity and benefit from them more efficiently.
Chemical composition medium has also a significant impact on behavior of
nanomaterial. It has been demonstrated that the interaction type between the
medium and nanoparticles can modify their properties such as size and toxicity.
Thus, the same kind of nanoparticles can manifest different toxicity behaviors,
depending on the media (Hou et al. 2013). Studies confirmed that chemical composition also influences their toxicity. In a research carried in vivo, it was seen that
soluble nanosilver caused toxicity, whereas TiO 2 exhibited no toxic effect (Griffitt
et al. 2008).
Like other factors, crystal structure has also a prominent effect on the behavior
of material. While some kind of crystal structure “say rutile TiO 2 ” caused DNA
damage, other crystal structure “say anatase TiO 2 ” showed no damage to DNA
(Gurr et al. 2005a, b).
Agglomeration of nanoparticles is another element responsible for toxicity.
Agglomeration is formed by accumulation of particles. Agglomerated particles are
generally accumulated in organs like liver, spleen, and lung. Because their excretion
from body takes relatively longer time, their adverse effects are also long-term ones.
Although they did not exhibit toxicity, it has been shown that agglomerate carbon
nanotubes are more harmful than well-dispersed carbon nanotubes (Wick et al. 2007).
The surface morphology of nanomaterials is a very critical parameter controlling
their behavior because interaction with media and other particles or molecules
occurs via surface. The adsorption of oxygen species, radicals, or transition metals
on nanomaterial has a great influence on the physical and chemical properties of
nanomaterials and in turn their interaction with other species. It has been shown that
2 Nanomaterials and Human Health
negatively charged, or neutral. The sign and magnitude strongly affect the nanomaterial behavior in various media. It has been reported that surface charge and particle
composition of nanoparticles are significant factors of their action and toxicity on
cellular processes (Beddoes et al. 2015). A positively charged material was shown
to penetrate cell membrane more easily than negatively charged or neutral nanoparticles (Georgieva et al. 2011). Also, toxicity of nanomaterials might be determined
by surface charge. In a study carried on zebrafish and mice embryos, positively
charged PAMAM dendrimers were observed to be toxic, while no toxicity effect
was detected for negatively charged PAMAM dendrimers (Heiden et al. 2007). Liu
et al. investigated the surface charge effect on cellular uptake, cytotoxicity, and
in vivo biodistribution of CdSe/ZnS quantum dots. They have demonstrated that
charged particles, especially negatively charged ones, were internalized by macrophage and cancer cells more efficiently than neutral particles. They have also shown
that distribution and cytotoxicity of nanoparticles were strongly dependent on surface charge (Liu et al. 2015). Wang et al. have shown that negatively charged Au
nanoclusters accumulated in liver and spleen took relatively longer time, while positive Au nanoclusters have an adverse effect on the blood system. They also confirmed that surface charge has a significant effect on tumor uptake. Negatively
charged Au nanoclusters exhibited the highest tumor uptake (Wang et al. 2016).
Since surface charge has a profound influence on material–biological system interaction, researchers have been trying to modify and control the surface charge of
materials in order to overcome their toxicity and benefit from them more efficiently.
Chemical composition medium has also a significant impact on behavior of
nanomaterial. It has been demonstrated that the interaction type between the
medium and nanoparticles can modify their properties such as size and toxicity.
Thus, the same kind of nanoparticles can manifest different toxicity behaviors,
depending on the media (Hou et al. 2013). Studies confirmed that chemical composition also influences their toxicity. In a research carried in vivo, it was seen that
soluble nanosilver caused toxicity, whereas TiO 2 exhibited no toxic effect (Griffitt
et al. 2008).
Like other factors, crystal structure has also a prominent effect on the behavior
of material. While some kind of crystal structure “say rutile TiO 2 ” caused DNA
damage, other crystal structure “say anatase TiO 2 ” showed no damage to DNA
(Gurr et al. 2005a, b).
Agglomeration of nanoparticles is another element responsible for toxicity.
Agglomeration is formed by accumulation of particles. Agglomerated particles are
generally accumulated in organs like liver, spleen, and lung. Because their excretion
from body takes relatively longer time, their adverse effects are also long-term ones.
Although they did not exhibit toxicity, it has been shown that agglomerate carbon
nanotubes are more harmful than well-dispersed carbon nanotubes (Wick et al. 2007).
The surface morphology of nanomaterials is a very critical parameter controlling
their behavior because interaction with media and other particles or molecules
occurs via surface. The adsorption of oxygen species, radicals, or transition metals
on nanomaterial has a great influence on the physical and chemical properties of
nanomaterials and in turn their interaction with other species. It has been shown that
2 Nanomaterials and Human Health