Temperature-Responsive PNIPAM-g-alginate Gel Wrapped with LbL Assembled Chitosan/DNA Membranes for Development of Controlled Drug Release System

Abstract

While considerable consumers experience more-than-recommended-dose usage of commercially available scar cream for scar therapy treatment, we report here a novel and smart thermally controlled drug delivery gel patch system for scar therapy purpose. The gel patch contains a core of amine-terminated-poly(N-isopropylacrylamide) (NH2-PNIPAM) grafted alginate wrapped with outer membranes consisting of layer-by-layer (LbL) assembled chitosan and DNA thin films. The outer membrane via LbL assembly controls the rate and profile of model dye rhodamine B. A dramatically reduced burst effect in the delivery process and a diffusion controlled behavior was observed for the proposed system. NH2-PNIPAM cross-linked onto side chain of alginate exhibits contraction and expansion above and below its lower critical solution temperature (LCST: 36℃) and therefore serves as a switch turning “on and off” the release of drug entrapped in the core. The difference in the release of Texas-red conjugated epidermal growth factor (EGF-TR) at 36℃ and 22℃ were monitored with fluorescence microscopy and the system showed higher release of EGF-TR at 36℃ than at 22 ◦C. Below LCST (at 22℃), the expanded NH2-PNIPAM resembles stretched arms that close the release of EGF-TR, while above LCST (at 36℃), the NH2-PNIPAM arms coil and allow the release of EGF, showing great potential for application in controlled drug release system.