Abstract
Electrospun nanofibers have the potential to achieve high drug loading and the ability to sustain drug release. Mechanical properties of the drug-incorporated fibers suggest the importance of drug–polymer interactions. In this study, we investigated the mechanical properties of electrospun polycaprolactone (PCL) and poly (D,L-lactic-co-glycolic) acid (PLGA) fibers at various blend ratios in the presence and absence of a small molecule hydrophilic drug, tenofovir (TFV). Young׳s modulus of the blend fibers showed dependence on PLGA content and the addition of the drug. At a PCL/PLGA (20/80) composition, Young׳s modulus and tensile strength were independent of drug loading up to 40wt% due to offsetting effects from drug–polymer interactions. In vitro drug release studies suggested that release of TFV significantly decreased fiber mechanical properties. In addition, mechanically stretched fibers displayed a faster release rate as compared to the non-stretched fibers. Finally, drug partition in the blend fibers was estimated using a mechanical model and then experimentally confirmed with a composite of individually stacked fiber meshes. This work provides scientific understanding on the dependence of drug release and drug loading on the mechanical properties of drug-eluting fibers.
Highlights
Electrospinning is a process that utilizes an electric field to continuously draw fibers from a viscous polymeric solution through rapid solvent evaporation
These examples demonstrate that fibers comprised of polymer blends have a great potential for tuning drug miscibility and the resulting drug–polymer interactions could lead to different release profiles
We demonstrated previously that PCL/PLGA (20/80) fibers provide zero-order drug release when loaded with 15 wt% TFV (Carson et al, 2016), and selected this composition to measure the effect of various TFV drug loading on mechanical properties of the bulk mesh
Summary
Electrospinning is a process that utilizes an electric field to continuously draw fibers from a viscous polymeric solution through rapid solvent evaporation. Fibers electrospun from polymer blends of polycaprolactone and polyglyconate were used in tissue engineering as biomaterials to support cell growth where fiber degradation and mechanical properties were dependent on polymer compositions (Schindler et al, 2013) Another promising biomedical application for electrospun fibers of polymer blends is the ability to modulate drug release (Chou et al, 2015). The sustained release behavior of cefoxitin sodium suggested drug entrapment within the hydrophilic block of poly(ethylene glycol)-b-poly(lactide) forming drug/poly(ethylene glycol)-b-poly(lactide) complex, which was further encapsulated in the polymer fibers after electrospinning. These examples demonstrate that fibers comprised of polymer blends have a great potential for tuning drug miscibility and the resulting drug–polymer interactions could lead to different release profiles. We used mechanical testing as a probe for drug–polymer interactions that could inform drug partitioning in blend fibers of polyesters loaded with a hydrophilic small molecule drug
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