Controlled release of a hydrophilic drug from coaxially electrospun polycaprolactone nanofibers

• Coaxial electrospinning with partially electrospinnable shell fluid resulted with sustained drug release profile closer to zero order drug release kinetics.
• Burst release of the drug was observed for the membrane synthesized with single electrospinning.
• Smaller fiber diameters were obtained by using partially electrospinnable PCL solution as shell fluid.
• Some compatibility might be present between PCL and ampicillin according to the ATR-FTIR spectra results.

A recent approach for controlled release of drugs is the production of core-shell fibers via modified coaxial electrospinning where a shell solution which is not fully electrospinnable can be used. In this study, this technique was used for achieving the controlled release of a model hydrophilic drug (ampicillin) which is known to have a low compatibility with the polymer (polycaprolactone). A partially electrospinnable shell fluid (4% (w/v) polycaprolactone (PCL) solution) and a fully electrospinnable core fluid (10% (w/v) PCL, 2% (w/v) ampicillin solution) were used in order to create ampicillin-loaded PCL nanofibers covered by a PCL shield. Scanning electron microscopy and optical microscopy images proved that the membranes have core-shell structured nanofibers. Fourier transform infrared spectroscopy demonstrated that some compatibility might be present between ampicillin and PCL. Finally, drug release studies showed that the drug release kinetics of core-shell products is closer to zero-order kinetics while the drug release kinetics of single electrospinning of the core resulted with serious burst release. Together, these imply that the application area of modified coaxial electrospinning in controlled release could be expanded to polymers and drugs with low compatibility.

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