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Topics in Current Chemistry (2020) 378:15
4.4.1 CNTs and Cell Growing
Nanobiotechnology can have a great impact in the management of nervous system
pathologies by developing optimal structures for neural prosthetic applications. The
design of biocompatible implants for neuron repair/regeneration ideally requires
high cell adhesion as well as good electrical conductivity. Carbon nanotubes entail
all of these requirements, including high binding affinity and excellent electrical
conductivity, making them ideal materials for neuro-implant development aimed to
grow neurons and repair neuronal damage. Some examples have already presented
in earlier. Lovan et al. [198] showed that carbon nanotubes possess a good surface
for supporting dendrite elongation and cell adhesion. Experiments were carried out
on neonatal hippocampal neuron networks cultured on dispersed MWCNTs. Results
suggested that the growth of neuronal circuits on a nanotube grid is accompanied
by a significant increase in network activity, probably due to the high electrical conductivity of these nanomaterials. In the same line, Mazzatenta et al. [199] described
the preparation of an integrated SWCNT–neuron system by growing hippocampal
cells on the CNTs. Theoretical and experimental results indicated that SWCNTs can
stimulate the activity of the brain circuits.
However, CNT applications in tissue regeneration or engineering expand far
beyond nervous tissue. Ren et al. [200] used CNTs to develop artificial myocardial
tissue where cell growth was aided by the conductivity of oriented CNTs. Special
nanotube geometry also beneficiated artificial bone generation, making CNTs a very
suitable bone scaffold both in vitro and in vivo [201, 202]. Finally, CNTs make an
important contribution in the generation of synthetic fiber muscle [203, 204].
4.4.2 CNT‑Based Hydrogels
Although conventional hydrogels are biocompatible and suitable for culturing or
fabricating different cell types and tissues, their low mechanical strength and lack of
electrical conductivity have limited their biomedical applications for skeletal muscles, cardiac and neural cells. Nevertheless, the development of hybrid nanocomposite systems can overcome these limitations enabling the preparation of bioscaffolds
with tunable electrical and mechanical features. In fact, in the last few years, CNTbased hybrid hydrogels are emerging as innovative candidates with applications in
regenerative medicine and tissue engineering [205]. Shin et al. [206] prepared different nanotube–hydrogel hybrid systems that showed significantly improved electrophysiological and mechanical properties. The authors seeded neonatal rat cardiomyocytes onto these hybrid MWCNTs hydrogels, obtaining functional cardiac
patches that showed excellent mechanical integrity and advanced electrophysiological functions. Another study reports the addition of functionalized MWCNTs to
alginate to generate composite hydrogels improving the mechanical, physical, and
biological features compared with the starting materials [207]. The obtained hybrid
MWCNT–alginate gels were porous, showed less degradation, enhanced HeLa cells
adhesion and had greater cell proliferation, proving the potential utility of these
structures as novel substrates for tissue preparation. Sun et al. [208] incorporated
SWCNTs into collagen hydrogels, which improved cell alignment and assembly,
203
Reprinted from the journal
Topics in Current Chemistry (2020) 378:15
4.4.1 CNTs and Cell Growing
Nanobiotechnology can have a great impact in the management of nervous system
pathologies by developing optimal structures for neural prosthetic applications. The
design of biocompatible implants for neuron repair/regeneration ideally requires
high cell adhesion as well as good electrical conductivity. Carbon nanotubes entail
all of these requirements, including high binding affinity and excellent electrical
conductivity, making them ideal materials for neuro-implant development aimed to
grow neurons and repair neuronal damage. Some examples have already presented
in earlier. Lovan et al. [198] showed that carbon nanotubes possess a good surface
for supporting dendrite elongation and cell adhesion. Experiments were carried out
on neonatal hippocampal neuron networks cultured on dispersed MWCNTs. Results
suggested that the growth of neuronal circuits on a nanotube grid is accompanied
by a significant increase in network activity, probably due to the high electrical conductivity of these nanomaterials. In the same line, Mazzatenta et al. [199] described
the preparation of an integrated SWCNT–neuron system by growing hippocampal
cells on the CNTs. Theoretical and experimental results indicated that SWCNTs can
stimulate the activity of the brain circuits.
However, CNT applications in tissue regeneration or engineering expand far
beyond nervous tissue. Ren et al. [200] used CNTs to develop artificial myocardial
tissue where cell growth was aided by the conductivity of oriented CNTs. Special
nanotube geometry also beneficiated artificial bone generation, making CNTs a very
suitable bone scaffold both in vitro and in vivo [201, 202]. Finally, CNTs make an
important contribution in the generation of synthetic fiber muscle [203, 204].
4.4.2 CNT‑Based Hydrogels
Although conventional hydrogels are biocompatible and suitable for culturing or
fabricating different cell types and tissues, their low mechanical strength and lack of
electrical conductivity have limited their biomedical applications for skeletal muscles, cardiac and neural cells. Nevertheless, the development of hybrid nanocomposite systems can overcome these limitations enabling the preparation of bioscaffolds
with tunable electrical and mechanical features. In fact, in the last few years, CNTbased hybrid hydrogels are emerging as innovative candidates with applications in
regenerative medicine and tissue engineering [205]. Shin et al. [206] prepared different nanotube–hydrogel hybrid systems that showed significantly improved electrophysiological and mechanical properties. The authors seeded neonatal rat cardiomyocytes onto these hybrid MWCNTs hydrogels, obtaining functional cardiac
patches that showed excellent mechanical integrity and advanced electrophysiological functions. Another study reports the addition of functionalized MWCNTs to
alginate to generate composite hydrogels improving the mechanical, physical, and
biological features compared with the starting materials [207]. The obtained hybrid
MWCNT–alginate gels were porous, showed less degradation, enhanced HeLa cells
adhesion and had greater cell proliferation, proving the potential utility of these
structures as novel substrates for tissue preparation. Sun et al. [208] incorporated
SWCNTs into collagen hydrogels, which improved cell alignment and assembly,
203
Reprinted from the journal