Biomedical Engineering Reference
In-Depth Information
and performance of polymer matrix in nanocomposites can be improved by
adding small percentages of CNTs less than 1% weight.
273
Transfer of the outstanding properties of carbon nanostructures from
nano- to microscale involves assembling and processing with polymers that is
hindered by their intrinsic poor solubility and processability.
127
This is solved
by sidewall carboxylic functionalization to improve their dispersion in polymer
matrix and their compatibility in biological fluids.
180
CNTs influenced the min-
eralization process that was also affected by the surface functionalization. The
nanotubes supported osteoblast matrix deposition, allowed mineralization, cell
differentiation, and bone-like tissue formation providing an effective nucleation
surface that induced the formation of a biomimetic apatite coating.
127,274
Wide-
spread attention has been focused on the use of CNTs with living entities and
biomedical application.
275,276,277
There has been extensive interest in applying the properties of CNTs to
various biological applications
278
including their use to reinforce scaffolds for
tissue engineering.
45
However, the toxicity and biocompatibility of CNT nano-
composites need to be thoroughly investigated.
279
In vitro studies have success-
fully grown different cell types on CNTs or CNT-based nanocomposites. In
unmodified nanotubes, neurons extend only one or two neurites while neurons
grown on nanotube coated with bioactive molecules lead to elaborate multiple
neurites, which exhibited extensive branching that established the feasibility of
using nanotubes as substrates for nerve cell growth and as probes of neuronal
function at the nanometer scale.
280
Because CNTs are similar in shape and size
to nerve cells, they could help to structurally and functionally reconnect injured
neurons.
127
Hippocampal neurons grown on nanotubes displayed a sixfold
increase in the frequency of spontaneous postsynaptic currents showing func-
tional synapse formation.
281
These results showed the performance of CNTs as
support devices for bridging and integrating functional neuronal networks in
vitro without causing significant neural damage.
281
Honeycomb-like matrices
of multiwalled CNTs were fabricated as potential scaffolds for tissue engineer-
ing.
282
These nanotube networks were used to culture mouse fibroblast cells that
formed a confluent layer that did not exhibit cytotoxicity.
Although there have been a large number of researches on the potential
biomedical applications of carbon nanostructures, information on toxicity and
biocompatibility has only come up recently.
283
In order to exploit the poten-
tial clinical applications of CNTs, toxicological and pharmacological studies
must continue in parallel to provide clear acceptable frameworks to regulatory
authorities and the public that may suggest guidelines for the safe use of CNTs
in medicine.
56
6.5.2.3 Nanocomposite Films
In order for a scaffold to be considered for use as cell culture substrate, its
properties must first be properly characterized and optimized. A variety of
processing methodologies to create dense nanocomposite films have been studies.
