Biomedical Engineering Reference
In-Depth Information
specific biointeractions with cell membranes, proteins, and other biological fluid compounds, which
may alter their behavior and properties based on the composition of the coating acquired in the
biological environment. Furthermore, localization of the nanoparticles is not always straightforward
due to their high mobility and ability to penetrate defense systems and translocate from the original
port of entry. This phenomenon can be beneficial in the delivery of medicines, but may also be
potentially very detrimental to health when exposure to nanomaterials is not intentional or when
the dosage and parameters of the nanoparticles, intended for medical use, are not appropriately
designed.
Concerns about the impact of nanotechnology on human health have been voiced repeatedly. In
2004, Donaldson was the first to emphasize the need for the development of a specific field of study
that would assess nanotoxicology, and develop and improve protocols for assessment of toxicology
profiles [1]. As the field of nanotechnology is very broad, enveloping multiple areas of study and
application ranging from computer technology to medical applications, there is expected to be an
increase in exposure to many different types of nanomaterials with an increase in their use. Thus,
understanding nanotoxicology becomes more of a priority. The characterization of specific toxicity
parameters of nanomaterials requires the collaboration of multiple disciplines, as the physicochemi-
cal properties change from physical scale to quantum scale properties. Another layer of complexity
is added when the entrance of these nanoparticles into the body is considered. First, the charac-
terization of these nanoparticles is primary in the understanding of their behavior. The chemical
description, including size, charge, surface area, surface properties, and the presence of receptor
ligands, is helpful in predicting the biointeractions of nanoparticles in the body. More specifically,
the transport of the nanoparticle throughout the body lends understanding of the potential accumu-
lation of nanoparticles that may impose a risk of toxicity. The projection of health effects is directly
linked to the understanding of the biological systems and its metabolic pathways. Furthermore,
normal metabolism may be modified by the presence of nanoparticles; thus, it is important to under-
stand the impact of the interaction of the nanoparticle with the biological system in order to deter-
mine toxicological effects of nanoparticles on overall health, which may be done by either adjusting
the design of the nanoparticle or the design of treatment alleviating the toxicological effect.
Although consumer reports and media outlets have been on the skeptical side, currently nurtur-
ing a phobic atmosphere concerning any application of nanotechnology, this field offers a plethora
of exciting possibilities of application of this innovative technology [2]. However, the success of
nanotechnology goes hand in hand with the development of the nanotoxicology field, as it is neces-
sary for establishing the border between the safe and dangerous. The parameters that are important
in understanding the toxicokinetics of nanoparticles are discussed in the sections to follow.
9.1.1 p
redIctINg
aNd
I
deNtIfyINg
h
ealth
r
Isks
After having considered the scope of the field of nanotechnology, the challenges of predicting health
risks are very obvious. Nanoparticles are made for a variety of applications, ranging from preser-
vation of freshness in the food industry to delivering active pharmacological ingredients (APIs) in
cancer therapy. For instance, metal nanoparticles, especially silver nanoparticles, are widely used
for their antibacterial properties. Such applications include wound dressings, food packaging, cos-
metic creams, textiles, and nasal sprays [3-7]. Manufactured nanoparticles inevitably escape into
the waste system and environment, where they can accumulate and enter the food chain. As com-
panies begin to embrace the use of silver nanoparticles, it becomes increasingly important to ensure
the scope of effective and safe dosages, and establish a known toxicological profile. In response to
the concerns about health effects, a large number of studies have been published assessing the toxic-
ity of silver and the extent of their antibacterial properties. Studies have been published determin-
ing the antibacterial properties in various conditions to range 0.1-20 mg/L; on the other hand, the
World Health Organization has identified no observed adverse effect level at 10 g (total cumulative
dose over a lifetime) [8]. However, excessively high dosages of silver lead to blue or bluish gray skin
