Biomedical Engineering Reference
In-Depth Information
cpTi
CNT-comp
FIGURE 3.5
Surface calcium mapping using EDS (Energy Dispersive Spectroscopy) on substrates with cells 4 weeks after
cell plating. The red dots indicate locations of calcium. All the three substrates showed uniform distribution of
calcium, while CNT-comp had higher amount of calcium compared to cpTi (commercially pure titanium)
(
0.05). (For interpretation of the references to color in this figure legend, the reader is referred to the web
version of this topic.)
P,
From Ref.
[219]
.
3.5.3
Protein, gene, and drug delivery
The findings that biomolecules such as proteins and DNA can be immobilized with CNTs
hollow cavity or on its surface have embarked significant research efforts on bioconjugated
CNTs potential role in gene therapy and drug delivery
[244,245]
. MWNT has higher ability to
adsorb proteins than graphite when the maturation of the osteoblast by MWNT was examined
[246,247]
. This finding of CNTs ability to adsorb proteins on its surface has indicated its
potential role as a carrier for protein or gene delivery. Also, the adsorption of the recombinant
human bone morphogenetic protein-2 (rhBMP-2) on the surface of MWNT
chitosan scaffolds
was shown to be satisfactory, and researchers were able to induce ectopic bone formation
by implanting MWNT
chitosan scaffold adsorbed with the rhBMP-2 in mouse muscle
(
Figure 3.6
)
[248]
.
Various functional groups can be attached to the tips or sidewalls of nanotubes to make functiona-
lized CNT which can be used for the delivery of drugs, proteins, and genes because functionalization
can improve CNTs solubility and biocompatibility
[249]
. During gene therapy, due to the potential
undesired immune and oncogenic side effects toward the viral vector, nonviral vectors such as
nucleic acid conjugate with cationic lipids and polymers, and nanoparticles have been explored as an
alternative to guarantee a high degree of safety
[250]
. Functionalized CNT was used as a gene deliv-
ery medium because the macromolecular and cationic nature of the functionalized CNT can help to
form supramolecular complexes with plasmid DNA
[251]
. Authors showed that supramolecular com-
plexes with plasmid DNA were successfully formed on f-SWNT, indicating the potential of functio-
nalized CNTs in gene therapy and genetic vaccination. Furthermore, it was reported that gene
expression offered by the supramolecular complexes of functionalized CNT and plasmid DNA was
five to ten times higher than that of DNA alone
[252]
.
