Electrospun Nanofibers of Purple Rice Bran-Derived Soluble Dietary Fiber and Polyethylene Oxide for Enhanced Alpha-Tocopherol Encapsulation and Controlled Release

Purple rice bran-derived soluble dietary fiber/polyethylene oxide-based composite nanofibers (SDF/PEO nanofibers) were developed to entrap alpha-tocopherol (α-TOC), thus enhancing its stability and facilitating controlled release. Entrapment of α-TOC into SDF/PEO nanofibers was achieved via electrospinning of SDF/PEO polymer solutions containing either droplets of α-TOC emulsion or α-TOC-loaded zein particles. The fiber diameter ranged from 199 to 283 nm with α-TOC loading, and the entrapment efficiency (EE) varied from 54.8 to 87.8%. When zein-encapsulated α-TOC particles were loaded, α-TOC/zein-SDF/PEO nanofiber diameters ranged from 283 to 325 nm, and the EE was between 57.0 and 74.5%. Nanofibers produced with both loading forms demonstrated controlled release of α-TOC in both phosphate buffer saline (PBS) medium and simulated gastrointestinal conditions. The physicochemical properties of the nanofibers were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The disappearance of zein’s melting peak was observed in the nanofibers, suggesting possibly enhanced thermoresistance of zein-encapsulated α-TOC particles in the nanofibers. It was determined that α-TOC-PEO nanofibers were more crystalline in structure than α-TOC-SDF/PEO nanofibers. SDF/PEO nanofibers have potential as a delivery system for α-TOC and can potentially be applied to other hydrophobic nutrients as well.