Biomedical Engineering Reference
In-Depth Information
and reasons behind the possible interactions between different types of cells and nanoparticles as
functions of its size, shape, and surface chemistry (Lewinski et al. 2008). Studies also mention that it
is difficult to derive any conclusions due to the variability of various nanoparticle parameters, such as
physicochemical properties, cell target, dosing parameters, and the biochemical assays used.
Recent studies have confirmed that the physicochemical characteristics of nanoparticles, such
as particle size, shape, surface area, solubility, chemical composition, and dispersion factor, play
very significant role in determining their biological responses (Oberdörster et al. 2005; Nel et al.
2006; Powers et al. 2006). For example, small-sized nanoparticles can enter the cell and mitochon-
dria through various pathways, subsequently inducing oxidative stress and cell death via apoptosis
(Xia et al. 2007). The relatively larger surface areas of nanoparticles can produce a large number
of reactive oxygen species (ROS), which can damage DNA (Karakoti et al. 2006; Hussain et al.
2009). Slightly or completely soluble nanoparticles might release toxic or nontoxic ions that undergo
chemical reactions to form ROS (Brunner et al. 2006). The entry of nanoparticles into cells is
dependent on the nature of the (charged) functional groups that coat their surfaces (Zhang and
Monteiro-Riviere 2009). Given this information, it is very important for researchers to determine
how these physicochemical characteristics of nanoparticles affect their biological responses. For
example, nanoparticles that have different abilities to generate reactive species (RS) have a greater
biological effect than the dependence on surface area (Sayes et al. 2006a,b,c).
“Nanotoxicity” is the study of the potential toxic impacts of different nanoparticles and nano-
materials on biological and ecological systems. Nanotoxicity studies arose from diverse fields, such
as molecular toxicology, material science, molecular biology, analytical chemistry, and engineer-
ing. The basic aim of the nanotoxicity field is to build design rules for the development of safe
nanoparticles. Therefore, systematic and scientific studies are essential and should be based on
well-characterized physicochemical properties and their effects on cellular-viability and -function
in relevant model systems. Risk assessment strives to determine risks based on the possibility of
exposure and the hazards of the potentially toxic substance—in this case, nanoparticles—to make
regulatory decisions (Sara et al. 2012).
3.1.1 a
dvaNtages
of
N
aNosysteMs
The two basic properties of nanoparticles, like their small size and biodegradability, are important
advantages for effective drug delivery (Singh and Lillard 2009). Nanoparticles have the following
advantages:
1. Because of their small size, they can extravasate through the endothelium in inflammatory
sites, epithelium (e.g., intestinal tract and liver), tumors, or penetrate microcapillaries. In
general, the nanosize of these particles allows for its efficient uptake by a variety of cell
types and its selective drug accumulation at target sites (Desai et al. 1997; Panyam and
Labhasetwar 2003; Panyam et al. 2003b).
2. They protect therapeutic agents against enzymatic degradation (i.e., nucleases and prote-
ases) (Ge et al. 2002).
3. They increase the aqueous solubility and bioavailability of the drug (Parveen et al. 2012).
4. They provide a targeted delivery of the drug by attaching targeting ligands to their surface
or by the use of magnetic guidance (Mohanraj and Chen 2006).
5. They decrease the toxic side effects of the drug (Parveen et al. 2012).
6. They allow the development of rapid formulations (Parveen et al. 2012).
7. Their controlled-release and particle-degradation characteristics can be readily modulated
by the choice of matrix constituents. Drug-loading capacities are relatively high and drugs
can be incorporated into the systems without any chemical reactions; this is an important
factor for preserving the drug's activity (Mohanraj and Chen 2006).
8. They offer appropriate forms for all routes of administration (Parveen et al. 2012).
