Electrospinning Stimuli-Responsive Fibers at the Nanoscale As Functional Drug Delivery Mats

Skin
tissue engineering and drug delivery are very relevant fields of research in
the health industry. Due to certain responses of the immune system, there has
yet to be a development of proper skin tissue substitutes. A challenge that
arises with this area of research is replicating a three-dimensional scaffold
that has the same function and structures as the natural extracellular matrix.
The scaffolds provide an alternative to the use of allografts and autografts
and can be also used for bone repair.² A
technique that has gained attention within this field of research in the last
couple of decades is electrospinning. This new technology allows scaffolds to
be created through electrospun nanoscale fibers with a large range of diameters,
which produces a porous structure with a high surface area.¹ In
addition to research of skin tissue engineering, drug delivery proves to be
another promising application of electrospun fibers. The high loading capacity
and localized Ð but time released Ð delivery of a large amount of therapies,
along with the cost effective processing technique of electrospinning, make
scaffold-facilitated drug delivery highly attractive. Dependent on whether
degradable or non-degradable materials are use, the drug release can occur via
diffusion or scaffold degradation.³ The
delivery rate at which the drug is released can also be altered, allowing for a
larger range of drugs able to be delivered such as antibiotics, anticancer
drugs, proteins and DNA.³

The objective of this research is to create biodegradable mats
with tunable characteristics such as fiber diameter and surface area. The
functional drug delivery mats enable disease-tailored therapies with targeted
delivery to reduce side effects in patients. Using a large electric potential
to draw fibers from a solution flowing at a specific rate, the solution
reaches a grounded target several inches away. The biodegradable controlled drug
delivery polymer used was poly(lactic acid-co-glycolic acid) (PLGA).
PLGA solutions of 11 Ð 14 wt.% were prepared by dissolving the block copolymer
in a solvent mixture containing tetrahydrofuran (THF) and
dimethylformamide (DMF) at a 3:1 volumetric ratio.
They were then electrospun at distances of 7 and 18 cm and rates ranging from
0.8 to 4 mL/h at a voltage of 15 kV. The nanoscale fibers will be used as drug
delivery mats and the kinetics of the
peptideÕs release-time will be tuned to occur in the range of one hour
to a week. In addition, solution rheology was performed on each PLGA solution to
measure viscosity, which is directly correlated to the fiber diameter of the
electrospun mats. Observing the impact of solvent on fiber spinning and
fiber diameter brings about many positive results in developing fully
characterized and well-understood fibrous mats for drug delivery.

Work
Cited

¹Ru, C.; Wang, F.; Pang, M.; et. al; Suspended,
shrinkage-free, electrospun PLGA nanofibrous scaffold for skin tissue
engineering. American Chemical Society 2015, 10872-10977.

²Gentile, P.; Chiono, V.; Camagnola, I.; Hatton, P., An
overview of PLGA-based biomaterials for bone tissue engineering. International
Journal of Molecular Sciences 2014, 3640-3659.

³Sill, T.; Recum, H., Electrospinning: Applications in drug
delivery and tissue engineering. Biomaterials 2008, 29.