Biomedical Engineering Reference
In-Depth Information
have demonstrated that SiO
2
NPs caused anomalous proinflammatory stimulations of endothelial
cells and fibrogenesis in Wistar rats [143,144]. In an
in vivo
study, Warheit et al. also found that nano-
sized SiO
2
NPs produced a greater pulmonary inflammatory response than quartz particles after the
instillation of the particles into the lungs of rats at doses of up to 5 mg/kg [145]. Lin et al. also inves-
tigated the toxicity of SiO
2
NPs in cultured human bronchoalveolar carcinoma-derived cells along
with crystalline silica as a positive control. Exposure to crystalline silica results in a significantly
reduced cell viability [146]. Kaewamatawong et al. found that on an equal mass basis, silica NPs
cause more severe bronchial cell necrosis and lung inflammation than similar particles of a larger
diameter (230 nm) [147].
Future investigations on the uptake and response of silica NPs will allow a better understanding
of the nanomaterial's sites of action. Such investigations must also elucidate strategies for enhancing
the beneficial applications of this material in biological systems, whereas reducing potential adverse
effects mediated through macrophage interactions.
11.5 CONCLUSION
Nanotechnology is a rapidly growing field that permits the development of materials with desired
property attributes. The properties of nanomaterials are currently being extensively engaged in
medicine in the form of vectors to transport drugs to targeted sites in the body. However, some
of these NPs have exhibited highly toxic effects. The properties of nanomaterials, such as their
highly reactive surfaces as well as their competence to cross through membranes, may result in
significant dangers, particularly in relation to their potentially high levels of toxicity. Toxicity
and the biodegradability of nanostructures and their deleterious effect on various organs (acute
and chronic) is of pivotal interest along with their probable interventions with other vital body
functions. In the case of nanomaterials, attention should not only be paid to its application but
consideration is also given to associated toxicity issues. A majority of the literature admits and
clearly specifies the need for the detailed toxicity profiling of the developed nanomaterials before
claiming their clinical use.
Several studies have clearly shown that the toxic effects measured are directly related to the
surface of the nanomaterials. These entities have a natural tendency to agglomerate, meaning
that they group together to form much larger particles. Most pharmaceutical applications require
unagglomerated NPs. In such a line, scientists are expediting vivid formulation strategies to stimu-
late deaggregation and attain individual, NP-based formulations. Preferably, the NP surface is
modified by solubilizers, targeting ligands, diagnostic agents, and imaging agents, as well as for
intended application. In addition to base surface properties, these surface modifications also elicit
a major impact on NP toxicity or safety. Although some of these functionalized formulations
may provide great improvements over existing medications and improve the quality of life for
patients with severe diseases such as cancer, asthma, and so on. All new technologies may bear a
high amount of unknown factors along with a lack of long-term exposure risks, but if the benefits
offered are dramatic then they could overcome certain drawbacks. Ideally, during the formulation
of NPs, investigators must consider these points that can influence the toxicity profile of the prod-
uct. Details are available on the pharmacology of these biomaterials, but little information exists
on their impact on toxicology.
Toxic effects have already been widely reported at the cellular as well as organ-system levels
(pulmonary, reproductive, renal, cutaneous cardiac). It is important to realize that the NP deposition
site in the lungs will be affected greatly by NP dimensions, which can change substantially through-
out the production process. Because of their very small size, these particles offer a large contact
surface per mass unit. It has been shown clearly that the degree of toxicity is linked to this surface
and to the surface properties of these NPs, rather than their mass.
In line with pulmonary drug delivery, the facets of nanotechnology have grown enormously,
and with this advancement in drug delivery approaches, investigators and healthcare professionals
