1 research outputs found
Electrospun Polymer Blend Nanofibers for Tunable Drug Delivery: The Role of Transformative Phase Separation on Controlling the Release Rate
Electrospun
fibrous materials have a wide range of biomedical applications,
many of them involving the use of polymers as matrices for incorporation
of therapeutic agents. The use of polymer blends improves the tuneability
of the physicochemical and mechanical properties of the drug loaded
fibers. This also benefits the development of controlled drug release
formulations, for which the release rate can be modified by altering
the ratio of the polymers in the blend. However, to realize these
benefits, a clear understanding of the phase behavior of the processed
polymer blend is essential. This study reports an in depth investigation
of the impact of the electrospinning process on the phase separation
of a model partially miscible polymer blend, PVP K90 and HPMCAS, in
comparison to other conventional solvent evaporation based processes
including film casting and spin coating. The nanoscale stretching
and ultrafast solvent removal of electrospinning lead to an enhanced
apparent miscibility between the polymers, with the same blends showing
micronscale phase separation when processed using film casting and
spin coating. Nanoscale phase separation in electrospun blend fibers
was confirmed in the dry state. Rapid, layered, macroscale phase separation
of the two polymers occurred during the wetting of the fibers. This
led to a biphasic drug release profile from the fibers, with a burst
release from PVP-rich phases and a slower, more continuous release
from HPMCAS-rich phases. It was noted that the model drug, paracetamol,
had more favorable partitioning into the PVP-rich phase, which is
likely to be a result of greater hydrogen bonding between PVP and
paracetamol. This led to higher drug contents in the PVP-rich phases
than the HPMCAS-rich phases. By alternating the proportions of the
PVP and HPMCAS, the drug release rate can be modulated