Page 202 - Biodegradable Polyesters

180 7 Electrospun Scaffolds of Biodegradable Polyesters: Manufacturing and Biomedical Application

for its stabilization. This aqueous phase is then mixed with the polyester solution
(organic phase) after surfactant addition. The final emulsion is submitted to
electrospinning [164]. In coaxial electrospinning, core–shell fibers are produced
using a different electrospinning setup, containing an inner and an outer capillary
tube. Core–shell fibers, where the biomolecule is localized at the fiber core,
protected by the polyester fiber shell, are produced in this way. A great advantage
of this system, described in different studies, is the reduction of the initial burst
phenomena. The fiber shell forms a barrier, protecting great or total initial release
of the encapsulated molecule [165]. Some examples of electrospun scaffolds with
controlled delivery of biomolecules systems used in tissue engineering are cited in
Table 7.3.

7.5
Conclusions

The combination of knowledge of basic sciences such as chemistry, physics, and
biology with materials science and cell therapy is starting point for the regener-
ation of tissue and organs. The use of electrospinning technique for producing
biodegradable and biocompatible scaffolds is a promising strategy to develop scaf-
folds to be employed in nanomedicine. The scaffolds can be used in association
with cells, growth factors, and can also be functionalized with bioactive molecules
for improvement of the biomaterial.
A great challenge of materials science in the field of surface functionalization of
polymers, and in particular in polyesters, is to control the grafting of specific func-
tional groups on the surface to tune the response of the material to a specific stim-
ulus, especially in biological applications. Surface functionalization as was shown
in several examples using different approaches tends to obtain a selected chem-
istry at the molecular level to target a specific final product. This scientific frontier
will be the source of much interest for both scientists and engineers because reach-
ing molecular control of these surface chemical processes will indeed increase the
potential of polyester bioapplications.
These biomaterials should guide cells, promote their local proliferation, and
improve the environmental to permit tissue regeneration in the lesion site aimed
at replacement of the natural tissue. The scaffolds can be used for regenerating the
spinal cord, peripheral nerves, skin, cartilage, vessels, bone, as well as other tissue.
The use of nanotechnology for producing electrospun scaffolds of polyesters is
the new frontier of tissue engineering for application in regenerative medicine.

References
1. Nair, L.S. and Laurencin, C.T. (2007) 2. Lim, S.H. and Mao, H.Q. (2009)
Biodegradable polymers as bioma- Electrospun scaffolds for stem cell
terials. Prog. Polym. Sci., 32 (8–9), engineering. Adv. Drug Deliv. Rev., 61
762–798. (12), 1084–1096.