Layer-by-layer self-assembly films for buccal drug delivery: the effect of polymer cross-linking

Abstract The goal of this study was the preparation of multilayer polyectrolyte films intended for buccal delivery of benzydamine (BZ). Another important issue was to evaluate the effect of polymer cross-linking as a means to enhance drug loading and ensure sustained drug release. LbL deposition technique was applied for the multilayer build-up. The deposition was performed by alternative dip-coating of corona pretreated polylactic acid substrates into chitosan and caseine solutions. Chitosan and casein deposition was followed by cross-linking with glutaraldehyde/sodium tripolyphosphate, and calcium chloride, respectively. For drug loading, the multilayers were soaked into benzydamine solution after chitosan cross-linking. The procedure was carried out until eight layers were laid. The formation of polyelectrolyte complex and the cross-linking occurrence were proven by ATR-FTIR. Further investigations on the morphology and topography of the samples were carried out by AFM. Moreover, swelling behavior, content uniformity, drug release and mucoadhesion were investigated. The experimental data displayed differences in the structure and surface properties of the films as per the cross-linking agent used. All the investigated parameters were influenced by the cross-linking mode. Double cross-linking of chitosan with glutaraldehyde and sodium tripolyphosphate proved to be the most appropriate method for the achievement of the desired goals.