Biomedical Engineering Reference
In-Depth Information
nanotoxicity is relatively new and the specific nanoparticle properties that influence cellular toxicity
are still not fully understood, a thorough characterization of the nanoparticle is essential.
3.5 NANOPARTICLES: PHYSICOCHEMICAL CHARACTERIZATION-DEPENDENT
TOXICITY
Nanotoxicology is the study of nanoparticle toxicities which are unusual and not seen in larger
particles. They have greater surface-area-to-volume ratios, higher its chemical reactivities and bio-
logical activities. Because of their large surface area, nanoparticles will, on exposure to tissues and
fluids, immediately adsorb onto the surface of the macromolecules they encounter. This may, for
instance, affect the regulatory mechanisms of enzymes and other proteins. Human skin, lungs, and
the gastrointestinal tract are in constant contact with the external environment. These are the most-
favorable points of entry for natural or anthropogenic nanoparticles. Injections and implants are
other possible routes of exposure, primarily limited to engineered materials. Some nanoparticles,
depending on their composition and size, can produce irreversible damage to cells by oxidative
stress and/or organelle injury (Buzea et al. 2007).
Several diseases with unknown causes, including autoimmune diseases, Crohn's, Alzheimer's,
and Parkinson's, appear to be correlated with nanoparticle exposures. Conversely, the toxic proper-
ties of some nanoparticles may be beneficial, as they are thereby able to fight disease at a cellular
level, and could be used as medical treatments by, for example, targeting and destroying cancerous
cells. Cristin Buzea et al. (2007) summarize the possible adverse health effects associated with the
inhalation, ingestion, and contact with nanoparticles as shown in Figure 3.5. They emphasize that
nanotoxicity depends on various physicochemical properties, like particle size, shape, aggregation,
chemical composition, crystalline structure, and surface functionalization. In addition, the nanotox-
Nanoparticles internalized
in cells
(Neurological disease:
Parkinson's disease,
Alzheimer's disease)
Brain
Mitochondria
Nanoparticle inhalation
Nucleus
Cytoplasm
(Asthma, bronchitis,
emphysema, and cancer)
Lungs
Membrane
Lipid vesicle
(Atherosclerosis,
vasoconstriction,
thrombus, and high blood
pressure)
Circulatory
system
Nanoparticles
ingestion
(Arrhythmia, heart
disease, and death)
(Disease of unknown
etiology in kidneys,
liver)
Heart
Gastrointestinal
system
(Crohn's disease, colon
cancer)
Other organs
(Podoconiosis Kaposi's
sarcoma)
Lymphatic
system
Orthopedic implant
wear debris
(Autoimmune
diseases dermatitis,
urticaria, and vasculitis)
(Autoimmune
diseases dermatitis)
Skin
FIGURE 3.5
Schematics of human body with pathways of exposure to nanoparticles, affected organs, and
associated diseases from epidemiological,
in vivo
and
in vitro
studies. (Reprinted with permission from Buzea,
C., Blandino, I.I.P., Robbi, K. 2007.
Biointerphases
2(4): M R17-M R172.)
