pH- and electro-responsive characteristics of silk fibroin-hyaluronic acid polyelectrolyte complex membranes

Abstract

pH-responsiveness of recently developed silk fibroin (SF) and hyaluronic acid (HA) polyelectrolyte complex (PEC) membranes and their potential use in electro-responsive drug release systems were investigated. PEC membranes were prepared within a narrow pH window (3.0-3.5) for a SF-HA weight ratio of 20 and they were characterized by Atomic Force Microscopy in addition to characterization studies previously reported by our group. Swelling kinetics of the membranes was studied for a pH window of 2.5-7.4 and cyclic swelling test was performed to determine the pH-responsiveness of the membranes. It was shown that membranes swelled more in alkaline conditions and responded to variations in pH of the medium. Electric-stimuli assisted drug permeation and release studies were performed with a custom-made diffusion cell under both passive condition and electric field applied in pulsatile fashion. The instantaneous flux raised as the current was applied and then declined when the current application was terminated, and this process was repeated on subsequent applications. SF-HA complex membranes were found promising for the electric-stimuli-sensitive release of a high molecular weight and charged model drug for a membrane-permeation controlled formulation.