Biomedical Engineering Reference
In-Depth Information
strated an increase in fi ber diameter with an increase in concentration of nanopar-
ticles as well as the base PCl solution. Also, high concentration of nanoparticles
led to improved tensile strength of the mats. Their further
in vitro
studies demon-
strated the potential of PCL-HA mats as bone scaffolding material due to
osteoblast-promoting activity of HA with no threat to osteoblasts and mouse
fi broblasts.
Silica has also been investigated as a potential candidate for bone-tissue
engineering as it possesses silanol groups that are essential for apatite formation,
thus resembling bone [232]. Sakai et al. demonstrated the proliferation of osteo-
blasts on electrospun nanofi brous meshes of silica. It was the fi rst study of its
type that reported apatite formation and its morphology on electrospun silicate
fi bers thereby confi rming the bone bonding ability essential for bone-tissue
engineering.
In the recent past, there has been an effort to develop active ceramic-
biodegradable polymer composites in bone-tissue engineering to overcome the
brittleness of the ceramic component and low mechanical strength of the poly-
meric component. However, this can potentially lead to other problems, such as
decreased affi nity of hydrophilic ceramic for organic solvent and hydrophobic
polymers, thereby resulting in poor/uneven dispersion of the ceramic component
within the polymeric matrix. Hence, Kim and co-workers designed a novel com-
posite system composed of uniformly dispersed hydroxyapatite powder in PLA
solution. The use of a surfactant, 12-hydroxysteric acid ensured uniform distribu-
tion of HA powder within the PLA matrix [233]. Electrospun nanofi brous
HA-PLA mesh composite demonstrated improved osteoblast attachment,
spreading and proliferation. Further, they demonstrated higher alkaline phospha-
tase (ALP a phenotypic marker of bone forming cells) expression on composite
scaffolds as compared to plain PLA scaffolds, thereby establishing their potential
in bone regeneration.
Electrospun matrices generated by synthetic polymers have demonstrated
advantages in terms of better cell adhesion and proliferation; however, their
hydrophobic nature has limited their use in certain tissue engineering applica-
tions. Hence, there have been attempts to augment the hydrophilicity of these
polymers by blending them with hydrophilic polymers. A study by Spasova et al.
explored the possibility of imparting hydrophilicity to hydrophobic PLLA elec-
trospun scaffolds by the incorporation of varying amounts of PEG, a hydrophilic
polymer. Nanofi brous PLLA-PEG electrospun meshes were synthesized by
varying the concentrations of PLLA as well as PEG and the applied fi eld strength
[234]. The PEGylated scaffolds demonstrated uniform cell adhesion (both osteo-
blasts and fi broblasts) on all electrospun meshes irrespective of PEG concentra-
tion. Furthermore, in long-term cultures, the authors reported the organization of
osteoblast-like cells into tissue-like structures, particularly on scaffolds with the
highest concentration of PEG (PLLA : PEG at weight ratio 70 : 30). This study
indicates that the presence of a hydrophilic polymer could modulate the cell
response, thereby resulting in controlled cell adhesion, and can play a key role in
scaffold design for application in bone-tissue engineering.
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