Biomedical Engineering Reference
In-Depth Information
5.1.2 N
aNotoxIcIty
Biomedical engineering, drug delivery, environmental health, pharmaceutical industries, and
even electronics and communication technologies, all incorporate nanotechnology, leading to
greater potentials for advancements in current research. For example, in the health-care field,
nanomaterials are being considered in the development of new drugs and new therapies for disease
control and improving the quality of life (Bianco et al. 2005; Slowing et al. 2007; Faraji and Wipf
2009). More recently, nanomaterials have been used in tissue engineering and medical imaging,
leading to improved diagnostics and new therapeutic treatments (Harrison and Atala 2007; Kim
et al. 2008; Shi 2009). However, due to their novel stature, nanoscale materials (including nano-
tubes, nanowires, nanowhiskers, fullerenes or buckyballs, and quantum dots) have to be tested
for unintended hazards for human health and the environment (Oberdorster et al. 2005; Kreyling
et al. 2006).
To ensure the compatibility of nanomaterials for medical applications and for the safety of
the environment, testing for toxicological parameters is a necessary first step in nanotechnology
research. The bulk material properties of metals change when they are in the nanoscale, and they
may pose certain threats to biological systems that their bulk counterparts may not. To date, a
number of studies are addressing nanotoxicity (Soto et al. 2005; Hillegass et al. 2010; Soenen et al.
2011); however, there is a variability of methods, materials, and cell lines used (Lewinski et al.
2008), leading to the need for a standard testing method, or methods, in nanotoxicity testing, which
is becoming increasingly important to validate these novel techniques.
The use of nanomaterials in biomedical sciences has placed nanomaterials directly in contact
with biological materials, and, thus, it is necessary to observe their interaction closely.
Another risk to be considered is the emission of hazardous air pollutants associated with the
use and manufacture of nanomaterials that contain particulate matter on the order of 1-100 nm in
size. Any material in the respirable size range, <100 nm in diameter, may have toxic effects on lung
fibroblasts after inhalation (Mossman et al. 2007). In particular, nanoparticles with sizes <20 nm
affect the alveolar region of the lung (Elder et al. 2009).
Methods such as the mitochondrial reduction of tetrazolium salts into an insoluble dye (the MTT
test) and enzyme lactate dehydrogenase (LDH) release tests are traditional
in vitro
biological meth-
ods used in the current nanotoxicity studies. These measure cellular viability and proliferation and,
thus, are used as markers for cell viability. They consist of procedures that provide a general sense
of cytotoxicity, as they show results only at a final time point (Hussain et al. 2005). As a result, the
kinetic model (absorption, distribution, metabolism, and excretion) of the nanoparticle uptake is not
usually observed with these conventional methods. Following biological exposure, the particles may
transport across cell membranes, especially into the mitochondria, causing internal damage that
may affect cell behavior and, over time, may lead to cell death (Wilhelm et al. 2002).
In this chapter, the various types of biosensors used to detect nanotoxicity will be explored. We
will explore biosensing methods measuring nanotoxicity toward cell monolayers, single cells, and
individual components of the cell. The integration of biomolecules with nanotechnology has great
future perspectives in the rapidly developing fields of environmental (pollution control and monitor-
ing) and biomedical research, drug delivery, electronics, and communication technologies. With the
increasing number of nanomaterial applications, assessing their toxicity should be the first impor-
tant step toward creating safety guidelines for their handling and disposal. Studies of the biological
effects of nanoscale materials that might answer these questions have lagged behind other aspects
of nanotechnology development. Biosensing technology is shown to be sensitive enough to measure
the micromotions of a cell and, is therefore able to monitor the progression of the cytotoxicity with
a rapid, real-time, and multisample analysis, creating a versatile, noninvasive tool that is able to
provide quantitative information with respect to alterations in cellular function under various nano-
material exposures.
