Reducing the Toxicity of Carbon Nanotubes and Fullerenes Using Surface Modifi cation Strategy - Management of Natural Resources in a Changing Environment - page 183

less cytotoxic after functionalisation and its extent depends on the degree of func-
tionalisation. CNTs modifi ed with suitable biomimetic polymers are also found to
be biocompatible while the uncoated CNTs lead to cell death.
It is not possible to draw conclusions on the effect of specifi c functionalisation/modifi ca-
tion on specifi c toxicity (Chawla and Kumar 2013 ) because of the limited studies
available and due to many variables involved in different toxicity studies (i.e., dose,
exposure time, exposure form, number, diameter, length, test species, end points
observed, etc.). However, it can be summarised that the toxicity of fullerenes and
carbon nanotubes can be controlled while formulating a product. The specimen
treatment process plays a signifi cant role in affecting the toxicity because of
residual solvents in the sample. The sonication method should be preferred over
the use of organic solvents. Attaching water solubilising groups, such as carboxyl or
alcohol groups increase the solubility and reduce the toxicity of fullerene. After
surface modifi cation, one can minimize/avoid the use of organic solvents during
specimen treatment process as it usually increases its solubility in water. Overall,
it can be summarised that functionalization plays a signifi cant role in reducing the
toxicity of fullerenes and CNTs and may alter the properties to some extent.
However, further studies are required in this area to make them compatible for
required application.
Acknowledgements The authors would like to thank Department of Science and Technology
(India) for supporting this study through the grant no: DST/TM/WTI/2K11/301(G) and Indian
Institute of Technology Delhi (India) for offering the Summer Faculty Research Fellowship to the
fi rst author.
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