This study investigated a novel type of drug-delivery membrane prepared by a modified coaxial electrospinning process. Using 1% (w/v) unspinnable zein solution as sheath fluid, the coaxial electrospinning process can be smoothly conducted to generate ketoprofen (KET)-loaded zein nanofibers coated with a thin layer of blank zein. Scanning electron microscopy and transmission electron microscopy images demonstrated that the nanofibers had a ribbon morphology with a smooth surface, as well as average diameters of 860 +/- 210 nm (coating thickness of ca. 20 nm) and 680 +/- 140 nm (coating thickness of ca. 30 nm) at sheath-to-core flow rate ratios of 0.11 and 0.25, respectively. X-ray diffraction and differential scanning calorimetry verified that KET presented an amorphous state in all nanofibers. Attenuated total reflectance Fourier transform infrared spectroscopy demonstrated that zein had good compatibility with KET because of hydrogen bonding. In vitro dissolution tests showed that the nanofibers coated with blank zein did not exert any initial burst release effect, and can enable linear drug release over a period of 16 h via a diffusion mechanism. The modified coaxial electrospinning process can provide new approaches to the development of nanofiber membranes with improved structural characteristics and performance. (C) 2012 Elsevier B.V. All rights reserved.