40
usage of fullerenes, scientists started to be concerned about their potential health
effects on human health. Scientist have found that these nanomaterials may have
cytotoxic effects, influence embryo development, and cleave DNA or scatter rapidly
to other tissues in the body (Tsuchiya et al. 1996). The nanoparticle was demonstrated to cause reactive oxygen species and peroxidation (Kamat et al. 2000).
Additionally, Sayes et al. have shown that cytotoxic potential of these structures can
be changed by about seven orders via surface modification (Sayes et al. 2004).
However, there is no consensus for now whether buckminsterfullerenes cause oxidative stress. While Oberdörster et al. reported that the structures were responsible
for oxidative stress, Zhu et al. claimed that the source of the stress is tetrahydrofuran
used to make nanoparticles soluble (Oberdörster et al. 2004; Zhu et al. 2006).
Through history, it seems that human immune system has evolved for fighting
against biological nanoparticles like viruses. However, it is not true for engineered
nanoparticles. Engineered nanoparticles may affect such innate defense system and
lead to inflammation. This is another issue to be solved since the knowledge of
interaction of nanoparticles and immune receptors is not sufficient to make general
and correct conclusions. Additional complexity arises when taking internalized
nanoparticles by protein into consideration.
It has been shown that the toxicity and inflammatory response of nanoparticles
were determined by the size of nanoparticles. Donaldson et al. reported that carbon
black with the size of 14 nm was about 3 times more toxic than carbon black having
50 nm size, while it was 10 times more toxic than its counterparts of 250 nm size
(Donaldson et al. 1999). Besides, Donalds et al. showed that there were almost no
differences in toxicity levels of titanium dioxide and latex (Donaldson et al. 2000).
There have been some in vivo experiments conducted to reveal the effects of engineered nanoparticles. Lam et al. demonstrated that pathological effects can last for
90 days post-exposure in mice (Lam et al. 2004).
Heavy metals also draw attention in terms of toxicology. In many hypotheses,
most of attention has been devoted to chemical processes rather than physical processes. Genotoxic damage has been explained as a process in which oxidative stress
through production of secondary photoelectron is linked to damage. Irradiation of
material by electromagnetic radiation leads to the creation of photoelectrons. Most
of photoelectrons are absorbed in bulk material, while many of electrons can
escaped from nano-sized material. Thus, these escaped electrons can enter the surrounding tissue and bring about the production of reactive oxygen species.
Cellular membranes are of great importance since they enclose every living cells.
They take part in many biological processes such as uptake of solid, fluid substance
and ions, gases exchange, and maintenance of ionic concentration. They are responsible for cell integrity. Thus, the efficiently functioning membrane is vital for cell.
The dysfunction of cell due to damage occurred in phospholipid bilayer via foreign
substances such as surfactant and lipid peroxidation may be extremely dangerous
for the cell. There are several mechanisms such as oxidative stress, inflammation,
and protein misfolding. In literature, there have been some findings which reveal
nanoparticles’ effects on essential parts of cell like mitochondria and nucleus. The
energy production center is mitochondria organelle, which is enclosed by two
S. Tekmen and S. Öksüz
usage of fullerenes, scientists started to be concerned about their potential health
effects on human health. Scientist have found that these nanomaterials may have
cytotoxic effects, influence embryo development, and cleave DNA or scatter rapidly
to other tissues in the body (Tsuchiya et al. 1996). The nanoparticle was demonstrated to cause reactive oxygen species and peroxidation (Kamat et al. 2000).
Additionally, Sayes et al. have shown that cytotoxic potential of these structures can
be changed by about seven orders via surface modification (Sayes et al. 2004).
However, there is no consensus for now whether buckminsterfullerenes cause oxidative stress. While Oberdörster et al. reported that the structures were responsible
for oxidative stress, Zhu et al. claimed that the source of the stress is tetrahydrofuran
used to make nanoparticles soluble (Oberdörster et al. 2004; Zhu et al. 2006).
Through history, it seems that human immune system has evolved for fighting
against biological nanoparticles like viruses. However, it is not true for engineered
nanoparticles. Engineered nanoparticles may affect such innate defense system and
lead to inflammation. This is another issue to be solved since the knowledge of
interaction of nanoparticles and immune receptors is not sufficient to make general
and correct conclusions. Additional complexity arises when taking internalized
nanoparticles by protein into consideration.
It has been shown that the toxicity and inflammatory response of nanoparticles
were determined by the size of nanoparticles. Donaldson et al. reported that carbon
black with the size of 14 nm was about 3 times more toxic than carbon black having
50 nm size, while it was 10 times more toxic than its counterparts of 250 nm size
(Donaldson et al. 1999). Besides, Donalds et al. showed that there were almost no
differences in toxicity levels of titanium dioxide and latex (Donaldson et al. 2000).
There have been some in vivo experiments conducted to reveal the effects of engineered nanoparticles. Lam et al. demonstrated that pathological effects can last for
90 days post-exposure in mice (Lam et al. 2004).
Heavy metals also draw attention in terms of toxicology. In many hypotheses,
most of attention has been devoted to chemical processes rather than physical processes. Genotoxic damage has been explained as a process in which oxidative stress
through production of secondary photoelectron is linked to damage. Irradiation of
material by electromagnetic radiation leads to the creation of photoelectrons. Most
of photoelectrons are absorbed in bulk material, while many of electrons can
escaped from nano-sized material. Thus, these escaped electrons can enter the surrounding tissue and bring about the production of reactive oxygen species.
Cellular membranes are of great importance since they enclose every living cells.
They take part in many biological processes such as uptake of solid, fluid substance
and ions, gases exchange, and maintenance of ionic concentration. They are responsible for cell integrity. Thus, the efficiently functioning membrane is vital for cell.
The dysfunction of cell due to damage occurred in phospholipid bilayer via foreign
substances such as surfactant and lipid peroxidation may be extremely dangerous
for the cell. There are several mechanisms such as oxidative stress, inflammation,
and protein misfolding. In literature, there have been some findings which reveal
nanoparticles’ effects on essential parts of cell like mitochondria and nucleus. The
energy production center is mitochondria organelle, which is enclosed by two
S. Tekmen and S. Öksüz