Environmental Engineering Reference
In-Depth Information
6.2 Attention to Nanotoxicity Is Required: Why? What Are
the Challenges?
Nanotechnology is an emerging technology and has applications in pharma (drug
delivery, imaging, etc.), food, and cosmetics. It offers wide range of advances but
attention to their side effects or toxicity effects is equally important. These
nanomaterials interact at cellular levels and while exerting advantageous effects
they also lead to some toxicological reactions if not formulated well. There are
several challenges in understanding their toxicological behavior. The main chal-
lenge in assessing toxicity mainly includes availability of limited analytical tech-
niques. It is very important to have validated, predictable materials characterization
tool and protocols to foresee the toxicity and hazard potential based on pharmacol-
ogy and toxicology response related to dose (acute and chronic exposure) alongside
with the determination of physiological reactivity (e.g. molecular, cellular, tissue,
organ toxicity). Currently, multiple techniques are available for macroscale bio-
materials and for soluble pharmaceutical products; however for nanoparticle,
development of such systems is still in preliminary phase. For implants, the
situation might be different to understand toxicity at local tissue. Another challenge
is to correlate results from literature and in vitro and in vitro experiments done.
There is a strong need to develop such a database where scientist can learn from
experiences, observation from others in developing own protocol to predict toxic-
ity. Other challenges are right choice of excipients, dose selection, type of cell line
and animal model selection and toxicity assessment protocol suitability. In the
following sections, these parameters are discussed one by one. These parameters
are related to the properties of nanoparticles as well as processing techniques.
6.3 Aspects of Nanotoxicity to Be Understood
6.3.1 Parameters Related to Nanoparticles
Toxic effects are sensitive, varied and complex and very much dependent on the
molecular interaction of nanoparticle at the cellular level which is directly affected
by the physico-chemical properties of the particles. Factors that might affect
toxicity depend on the type of nanoparticles and their composition, e.g. metal,
magnetic or polymeric nanoparticles. Factors such as composition, capillary forces,
optical effects, color, melting points, conductivity, ionization potential, electron
affinity, magnetism, surface energy, and reactivity contribute to the toxicity. Sur-
face topology, porosity, texture, and high-density fabrication are must considered
factors (Fig.
6.2
).
Other nanoparticle properties that affect toxicity and induce bioreactions in body
are intrinsic colloidal instability, aggregation phenomena in aqueous milieu,
bio-accumulation in the tissues, adsorption and transport phenomenon. Currently,
