Layer-by-layer assembly of Chitosan and Quince seed gum polyelectrolytes as a pH-responsive, on-off switchable multilayer film for controlled release of Ibuprofen

Abstract

Polysaccharide-based multilayer films have shown substantial potential for drug delivery applications. In the meantime, researchers have been captivated by Quince seed gum (QSG) with a high content of acidic polysaccharides because of its versatile responsiveness to salts, pH, and solvents. Accordingly, polyelectrolyte multilayers using Chitosan (CS) and Quince seed gum (QSG) were constructed and the effects of assembly pH, salt concentration, and post-assembly pH were systematically investigated. It was evident that both mass per unit area (10,000 ng/cm2) and the wet thickness (107.8 nm) after the deposition of 5 bilayers were accurately estimated by the viscoelastic model due to the highly swollen state of films. Atomic force microscopy could feasibly demonstrate the development of globular structures during the layer-by-layer assembly. Ellipsometry analysis showed that the variation of assembly pH resulted in conformational changes from extended to coiled. Consequently, different optical thicknesses as well as transitions from exponential to linear growth were observed. Moreover, extrinsic charge compensation was responsible for coiling or extensive counterion screening of polyelectrolyte chains depending on the NaCl concentration. CS/QSG films displayed pH-stimulus responsive on-off switching behavior at pH 2 and 7.4 for 3 cycles. The constructed film could absorb 1200 ng/cm2 Ibuprofen within 60 min at pH 7.4. The in vitro release kinetics from Ibuprofen-loaded samples showed pH dependency. The CS/QSG multilayer film can be considered as a smart pH tunable system for drug loading/release applications.