Biomedical Engineering Reference
In-Depth Information
icity to an organism is also determined by the individual's genetic complement, which provides the
biochemical toolbox by which it can adapt to- and fight toxic substances (Buzea et al. 2007).
Figure 3.5 shows the most extreme adverse health effects produced by nanoparticles in different
parts of body tissues and organs; there is a high need to increase the awareness of potential toxici-
ties of some nanoparticles. Diseases associated with inhaled nanoparticles are asthma, bronchitis,
emphysema, lung cancer, and neurodegenerative diseases, such as Parkinson's and Alzheimer's.
Nanoparticles in the gastrointestinal tract have been linked to Crohn's disease and colon cancer.
Nanoparticles that enter the circulatory system are related to the occurrence of arteriosclerosis,
blood clots, arrhythmia, heart diseases, and ultimately cardiac death. Translocation to other organs,
such as the liver, and spleen, may lead to diseases of these organs as well. The exposure to some
nanoparticles is associated with the occurrence of autoimmune diseases such as, systemic lupus
erythematosus, scleroderma, and rheumatoid arthritis (Buzea et al. 2007).
There are a number of factors responsible for the toxicity of nanoparticles: (1) The toxicity of
bulk materials, for example, heavy metals whose toxicity is easy to quantify (Curtis et al. 2006);
(2) the electrical properties of nanoparticles, as they can create and/or scavenge ROS and free radi-
cals (Oberdörster et al. 2005; Curtis et al. 2006; Lanone and Boczkowski 2006; Berube et al. 2007;
Duffin et al. 2007; Medina et al. 2007); (3) the size of nanoparticles may be linked to the toxicity
of nanoparticles as mentioned in ultrafine particle studies (Curtis et al. 2006). The formation of
ultrafine particle agglomerates is also responsible for toxicity. They pass through biological barriers
such as the skin, vascular endothelium, and the blood-brain barrier, therefore affecting the absorp-
tion, distribution, and excretion of these particles (Oberdörster et al. 2005; Moghimi et al. 2005;
Curtis et al. 2006; Garnett and Kallinteri 2006; Lanone and Boczkowski 2006; Hagens et al. 2007);
(4) shape is one of the factors that determines toxicity, for example, CNTs (Oberdörster et al. 2005;
Moghimi et al. 2005; Curtis et al. 2006; Lanone and Boczkowski 2006; Badea et al. 2007; Wagner
et al. 2007; Warheit et al. 2007); and (5) nanoparticles can also trigger immune responses. However,
studies are currently under way to identify their role in possible allergic reactions (Moghimi et al.
2005; Curtis et al. 2006; Lanone and Boczkowski 2006).
From the understanding of the toxicological properties of fibrous particles, it is believed that the
most important parameters in determining the adverse health effects of nanoparticles are the dose,
dimension, and durability (Oberdörster 2002). However, recent studies show different correlations
between the various physicochemical properties of nanoparticles (Table 3.5) and the associated
health effects, raising some uncertainties as to which are the most important parameters in deciding
their toxicity: mass, number, size, bulk or surface chemistry, aggregation, or all of them.
TABLE 3.5
List of Physicochemical Characteristics of Nanoparticles Induced Nanotoxicity
S. No.
Physicochemical Characteristics of Nanoparticles Involved in Toxicity
1
Structural properties of nanoparticles
a. Particle shape and aspect ratio
b. Structural arrangement (crystalline form)
c. Surface chemistry and charge
2
Dose
3
Concentration
4
Size, size distribution and surface area of nanoparticles
5
Material composition of formulation
6
Biopersistence solubility
7
Cellular uptake and binding
8
Surface coatings/modifications
