Selective pH-Responsive Core Sheath Nanofiber Membranes for Chem/Bio/Med Applications: Targeted Delivery of Functional Molecules

Core sheath fibers using different Eudragit materials were successfully produced, and their controlled multi-pH responses have been demonstrated. Core sheath fibers made of Eudragit L 100 (EL100) core and Eudragit S 100 (ES100) sheath provide protection and/or controlled release of core material at pH 6 by adjusting the sheath thickness (controlled by the flow rate of source polymer solution). The thickest sheath (similar to 250 nm) provides the least core release,similar to 125%/h, while the thinnest sheath (similar to 140 nm) provides much quicker release similar to 16.75%/h. Furthermore, switching core and sheath material dramatically altered the pH response. Core sheath fibers made of ES100 core and EL100 sheath can provide a consistent core release rate, while the sheath release rate becomes higher as the' sheath layer becomes thinner. For example, the thinnest sheath (similar to 120 nm) provides a core and sheath release ratio of 1:2.5, while the thickest sheath (similar to 200 nm) shows only a ratio of 1:1.7. All core sheath Eudragit fibers show no noticeable release at pH 5, while they are completely dissolved at pH 7. Extremely high surface area in the porous network of the fiber membranes provides, uch faster (>30 times) response to external pH changes as compared to that of equivalent cast films.