Page 302 - Biodegradable Polyesters

280 11 Electrospun Biopolymer Nanofibers and Their Composites for Drug Delivery Applications

PLGA randomly-oriented nanofiber 120 PLGA aligned nanofiber
Drug release ratio (%) 140 PLGA/Gelatin (9/1) film Drug release ratio (%) 140 PLGA/Gelatin (9/1) aligned nanofiber
PLGA film
PLGA randomly-oriented nanofiber
PLGA/Gelatin (9/1) randomly-oriented nanofiber
PLGA/Gelatin (9/1) randomly-oriented nanofiber
120
100
100
80
80
60
60
40
20
20 40
0 0
0 300 600 900 1200 1500 0 400 800 1200 1600
(a) Time (min) (b) Time (min)
Figure 11.3 Release curves of FBF from PLGA/gelatin (9/1) electrospun nanofibers (b).
FBF-loaded PLGA and PLGA/gelatin (9/1) (Reproduced with permission from Ref. [37];
electrospun nanofibers and solvent-cast films Copyright 2011 Elsevier.)
(a), aligned and randomly oriented PLGA and
Buschle-Diller et al. [39] focused on the preparation of PLA and PCL as well
as bicomponent fibers of PLA and PCL incorporating three different model
antibiotics. Since PCL almost completely liberated any of the drugs over time
while PLA only released about 10%, release characteristics could be modified
to fit a sensible drug delivery by forming bicomponent PCL–PLA fibers. Natu
et al. [40] reported electrospun bicomponent fibers of two semicrystalline
polymers, PCL and poly(oxyethylene-b-oxypropylene) for controlled drug release
applications. The release kinetics and regression analysis results implied a
three-stage release mechanism: the first stage was dissolution of the crystalline
drug that was not totally encapsulated in the fibers, followed by erosion (for
bicomponent fibers) or drug desorption and subsequent diffusion through
water-filled pores of PCL fibers, while the last stage was controlled by poly-
mer degradation. Since the components and stimuli-responsive properties of
fibers are important factors influencing their drug release behavior, Lin et al.
aimed at fabricating thermo-responsive poly(N-isopropylacrylamide) (PNI-
PAAm)/polyurethane (PU) nanofibers using a single-spinneret electrospinning
technique. The electrospun nanofibers were used as drug carriers by co-spinning
with nifedipine (NIF) and the release behavior of NIF can be effectively controlled
by adjusting the temperature of environment surrounding the thermo-responsive
nanofibers [41].

11.2.3
Drug-Loaded Nanoparticle/Biopolymer Composites

Owing to the high pore volumes for storage and delivery of drugs, as well as their
excellent photoluminescence properties, mesoporous materials functionalized
with photoluminescence show great potential applications in fields of controlled
drug delivery, disease diagnosis, and therapy. Luminescent, mesoporous, and