Biomedical Engineering Reference
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ensures significant area for cellular attachment. This enables higher density of cells to be cultured
when compared to 2D flat surface. In addition, synthetic electrospun polymer scaffolds are amena-
ble to surface modification with different functional groups that provide integrin-binding specificity
[114] . Hence, electrospun nanofibers combine topographical and biochemical cues within a single
scaffold to provide synergistic impact [113] . The material selection (biodegradable or nondegrad-
able) can be used to control over drug release kinetics—via diffusion for nondegradable polymers
or diffusion and scaffold degradation for biodegradable polymers.
Electrospinning also offers the opportunity to align the nanotubes along the axis of the fibers.
Mechanical (modulus and strength), electrical, magnetic, and optical properties of CNT compo-
sites are affected by alignment of nanotubes in the matrix. Because of the sink-like flow in the
wedge of the syringe, the nanotubes become oriented in the direction of flow. The aligned CNT
in the fiber increases the surface area for contact with the polymer matrix and enhances the
aspect ratio for reinforcement. Cells cultured on electrospun scaffolds have been shown to adhere
and elongate along the fiber axis [115
117] .Alignmentcanalsobeachievedbydepositingthe
fibers onto a rotating collector or to the edge of a spinning disk which orients the fiber along the
axis of rotation ( Figure 3.1 ). Fiber orientation is relevant since many tissues such as skeletal mus-
cle tissue, ligaments, articular cartilage, and blood vessel walls intrinsically possess anisotropic
cell organization. The orientation of the fiber induces anisotropy. This is critical to mimic in vivo
the function of skeletal muscle cells, whose alignments permit the fusion of myoblasts into myo-
tubes which forms the structural building blocks of densely packed muscle fibers that generate
longitudinal muscle contraction [118] .ElectrospunPCL
MWNT scaffolds seeded with primary
rat muscle cells displayed multinucleated cells with interacting actin filaments [117] . Smooth
muscle cells attached and migrated along the axis of electrospun poly( L -lactate-co-
-caprolactone)
copolymer [119] . In addition, it was reported [116] that electrically stimulated Poly (Lactic Acid)
(PLA/MWNT) enhanced osteoblast growth along the axis of aligned nanofibers. This is an exam-
ple of synergistic effect of electrical stimulation and topological cue on osteoblast growth that an
electrospun nanofiber can induce ( Figure 3.2 ).
ε
(A)
(B)
(C)
5
µ
m
5 µ m
5 µ m
FIGURE 3.2
Scanning electron micrographs of polystyrene solution with different MWCNT concentration: (A) 0.5%,
(B) 5%, and (C) 7%.
From Ref. [110] .
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