Core-sheath nanofibers prepared using coaxial electrospinning were investigated for providing biphasic drug release profiles. With ketoprofen (KET) as the model drug, polyvinylpyrrolidone and zein as the sheath polymer and core matrix, respectively, the coaxial process could be carried out smoothly and continuously without any clogging of the spinneret. Scanning electron microscopy and transmission electron microscopy observations demonstrated that the nanofibers were linear with homogeneous structure and had a clear core-sheath structure with an average diameter of 730 ± 190 nm, in which the sheath had a thickness of ca. 90 nm. Differential scanning calorimetric and X-ray diffraction analyses verified that all the components in the core-sheath nanofibers were present in an amorphous state. Attenuated total reflectance Fourier transform infrared spectra demonstrated both the sheath and core matrix had good compatibility with KET owing to hydrogen bonding. In vitro dissolution tests showed that the nanofibers could provide an immediate release of 42.3% of the contained KET, followed by a sustained release over 10h of the remaining drug. The present study exhibited a simple and useful approach to systematically design and fabricate nanostructures using coaxial electrospinning for providing biphasic drug release profiles.
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