NANOTECHNOLOGY: A TOOLKIT FOR CELL BEHAVIOR - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 4

they are alike in that carbon nanotubes can provide important augmentations to biomaterial scaffolds
to increase the efficacy of the constructs. In bone tissue engineering, the main concern of researchers
attempting to create an ideal tissue-engineered scaffold is modulating the mechanical properties of
biomaterials to be similar to that of natural tissue. They seek to not only strengthen scaffolds, but also
activate the mechanotransductive pathway that induces osteogenesis in human bone marrow MSCs
( Engler et al . , 2006 ). By incorporating MWCNTs researchers were able to not only increase the me-
chanical strength of poly(caprolactone) (PCL) scaffolds, but also increase adhesion, proliferation, and
differentiation of rat MSCs ( Pan et al . , 2012 ). In addition, our lab created a new 3D nanocomposite
scaffold based on magnetically treated SWCNTs ( Figure 1.2 A), nanocrystalline hydroxyapatite (nHA),
and chitosan hydrogel for improved bone regeneration ( Im et al . , 2012 ). Human fetal osteoblasts ad-
hered and proliferated more vigorously on nano scaffolds with magnetically treated SWCNTs over
nonmagnetically treated SWCNTs. Notably, the spreading morphology on the magnetically treated
SWCNT-augmented scaffolds showed extended filopodia, indicative of strong cell attachment. This ef-
fect was further explored by another study in our lab. A nanocomposite coating consisting of magneti-
cally treated SWCNTs and nHA was created, and deposited onto titanium for analysis. Samples coated
with SWCNTs exhibited increased MSC and osteoblast adhesion and proliferation when compared to
uncoated controls, and samples treated with nonmagnetically treated SWCNTs ( Wang et al . , 2012 ).
These papers also highlight the possible synergistic effect present when combining multiple nanoma-
terials within a single orthopedic implant. Moreover, Abarrategi et al . fabricated a scaffold using the
freeze-drying method to create fibrous scaffolds consisting of up to 89% MWCNTs. Scaffolds per-
formed well when seeded with myoblastic mouse cell C2C12 (with osteogenic potential) in vitro and
supported favorable cellular adhesion and proliferation results. The nano scaffolds were then implanted
in a mouse subcutaneous muscular pocket defect, and showcased quick degradation and the beginnings
of collagen formation at the interface of native tissue and the scaffold ( Abarrategi et al . , 2008 ).
FIGURE 1.2
(A) Scanning electron microscopy (SEM) image of hydrogen-purified MWCNTs. (B) Transmission electron
microscopy (TEM) image of magnetically treated SWCNTs.