Self-assembled polysaccharide-based multilayer nanofilms of xanthan gum and diethylaminoethyl dextran on gold substrate and their interaction with model biomacromolecules

In this study, we investigate the formation of electrostatically self-assembled multilayer films (MLFs) of the anionic xanthan gum (XG) and the cationic diethylaminoethyl dextran (DD) polysaccharides. XG/DD MLFs are formed on a gold (Au) surface by implementing the layer-by-layer (LbL) method. The MLFs are comprised of 10 alternating single layers (5 double layers) of the two oppositely charged polysaccharides. The constructed MLFs are studied by using the surface plasmon resonance (SPR) and the quartz crystal microbalance with dissipation (QCM-D) methods. The reported adsorbed masses Γ of the layers are within the range of 8-14 mg/m². Bovine serum albumin (BSA) showcases satisfactory adsorption and interaction with the MLFs both in neutral and acidic environments with increment Γ values of ~3 mg/m², while porcine gastric mucin (PGM) exhibits similar behavior in neutral environments. The XG/DD MLFs show decent stability against the increase of ionic strength and the rinsing with water between successive biopolymer deposition cycles. MLFs with adsorbed BSA and PGM show minimal mass losses due to pH changes and increased ionic strength, respectively. In general, the XG/DD MLFs are considered as promising options for use in drug delivery systems, wound-healing scaffolds, and biosensors, as well as for combating microbial growth due to the charges of the uncomplexed segments of the polysaccharides.