Soft Matter Composites Interfacing with Biomolecules, Cells, and Tissues - Bioinspired Approaches for Human-Centric Technologies - page 58

2.9 Multicomponent Electrospun Mats

The ideal wound dressing materials should follow the different phases of the
wound-healing process by providing to the wound the right substances at the
right time in order to optimize the wound-healing processes and times. A few
works have demonstrated the use of multicomponent electrospun mats, for a
simultaneous or a stepwise release of the active agents in specific stages of the
wound-healing process. In particular, composite electrospun mats of poly(lactic-co-
glycolic acid) with mesoporous silica nanoparticles were used for the co-encapsu-
lation and prolonged simultaneous release of the hydrophilic model drug rhodamine
B and the hydrophobic model drug fluorescein. The codrug delivery system can be
very useful for wound dressings that require combined therapy of several kinds of
drugs (Song et al. 2012a ). Further work of the group on the same system showed
that the release of the two drugs can be monitored separately. Most of the fluores-
cein was released rapidly during the 324 h of the trial, but the rhodamine B showed
a sustained release behavior (Song et al. 2012b ).
Multicomponent systems can be also considered all the core-shell electrospun
fibers. Especially for wound dressing applications, the use of electrospun mem-
branes that consist of core-shell fibers is gaining increasing interest. To prepare
such fibers using electrospinning, two different polymers can be separately deli-
vered to the inner and outer channel of a coaxial-tube spinneret. Different active
agents can be loaded to the core and to the shell of the fibers in order to obtain their
sustainable delivery to the wound. Wang et al. used poly( DL -lactic acid) and poly
(3-hydroxybutyrate), two biodegradable polymers, for the production of core-shell
nanofibers with the possibility to swap the material for the core and the shell. Using
poly(3-hydroxybutyrate) as the shell, the loaded dimethyloxalylglycine drug could
be released in a controllable manner. Whereas the single component fibers showed
an immediate release, the core-shell fibers showed two-stage release kinetics when
the drug was embedded in the core. The amount released in the first stage was 25 %
within 60 h, independent from the shell thickness. In the second stage, the release
rate was controlled by the thickness of the shell and was linear (Wang et al. 2010 ).
Another very recent work demonstrated the use of core-shell nanofibers of gelatin
and poly( L -lactic acid)-co-poly-(

-caprolactone) to encapsulate multiple epidermal
induction factors such as the epidermal growth factor, insulin, hydrocortisone, and
retinoic acid. When the same fibers were blend spun, an initial 44.9 % burst release
of the active agents was observed during the first 15 days, whereas no burst release
was detected from the core-shell nanofibers. Moreover, the proliferation and
differentiation to epidermal lineages of stem cells on the core-shell nanofibers
were higher with respect to the blended fibers (Jin et al. 2013 ). In a similar way, the
antibiotic gentamicin was encapsulated in coaxial fibers containing a skin of PLA
and a core of collagen using electrospinning in order to provide to wounds a strong
and time-controllable antibacterial release (Torres-Giner et al. 2012 ).

ʵ