Coaxial electrospinning using a concentric Teflon spinneret to prepare biphasic-release nanofibers of helicid

Abstract

A special concentric spinneret with a section of Teflon tubing as sheath nozzle was manufactured and used to perform coaxial electrospinning for generating biphasic-release core–sheath nanofibers of helicid. Two experiments were designed to investigate the interfacial interactions of working fluids with the components of the spinneret nozzle. Appropriate solvent systems were selected and used to prepare (1) an electrospinnable sheath fluid consisting of helicid and polymer filament-forming matrix, and (2) an unspinnable core fluid consisting of Eudragit® L100-55 and a relatively high content of helicid. At a 5 : 1 sheath-to-core flow-rate ratio, helicid-loaded nanofibers with an average diameter of 660 ± 210 nm, clear core–sheath structure, as well as smooth surface and cross-section were successfully produced, as verified by SEM and TEM observations. DSC and XRD analyses indicated that the nanofibers were essentially polymeric matrix composites with homogeneously distributed guest helicid molecules on the sheath and core part. ATR–FTIR spectra verified that hydrogen bonding occurred between the drug and core–sheath matrices. In vitro dissolution tests showed that the core–sheath nanofibers can provide biphasic-release profiles with 52.4% immediate release in simulated gastric fluid and 46.3% sustained release of the remaining drug in pH 7 simulated gastric fluid. These findings indicated that the non-metallic concentric spinneret could be exploited to conduct coaxial electrospinning and facilitated the smooth and continuous preparation of electrospun core–sheath nanofibers for providing biphasic drug release profiles.