Biomedical Engineering Reference
In-Depth Information
ofnanofiber-based3Dscaffoldsusingvariousbiopolymersandsyn-
thetic biodegradable polymers has currently become an active area
of research.
Polymeric nanofibers have also been investigated as a novel
wound dressing and as hemostatic devices. 14 The high surface area
of nanofiber matrices allows for oxygen permeability as well as
prevents fluid accumulation at the wound site. On the other hand,
the small pore size of the matrices e ciently prevents bacter-
ial penetration, making them ideal candidates for wound dress-
ings.Furthermore, flexibility of the electrospinning process allows
for co-spinning polymers with drugs or proteins, thereby making
the nonwoven nanofiber matrix a drug delivery matrix, which could
enhance woundhealing.
A number of synthetic polymer nanofibers with fiber diameters
from a few tens to a few hundreds of nanometers have been fab-
ricated for tissue engineering; these include polyglycolide (PGA),
poly( L -lactic acid) (PLLA), and their copolymers poly(glycolide-
co -lactide)(PLGA)andpoly( ε -caprolactone) (PCL). Studies have
demonstratedfavorablebiologicalresponsesofseededcells,suchas
enhanced cell attachment and in vitro proliferation. It is important
to have a 3D structure of a scaffold for cell attachment, growth, and
migration. For tissue engineering, nanofibrous structures positively
promote cell-matrix interactions. 10 Cells seeded on a nanofibrous
scaffold should have an appropriate interaction with their environ-
ment, that is, the cells maintain a normal phenotypic shape, adhere
onto the fibers, proliferate on the nanofibrous network, pack the
structure,andfinallyintegratewiththesurroundingfiberstoforma
3D cellular network (Fig. 12.3).
Recently, there has been a growing interest in the synthe-
sis of natural polymer-based nanofibers because of their proven
biocompatibility and their resorbable biodegradation products.
Advantageous attributes of natural polymers include hydrophilicity,
nontoxicity, and a less immune reaction, as well as enhanced cell
adhesion and proliferation. Collagen, gelatin, hyaluronan, chitosan,
and alginate are the most commonly used natural polymers in tis-
sue engineering. In a few recent studies, collagen and chitosan have
beensuccessfullyfabricatedintonanofibersandhavedemonstrated
good cellular compatibility. 13 The ability to generate nanofibrous
 
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