Novel protein-repellent and antimicrobial polysaccharide multilayer thin films

Nanostructured and bio-active polysaccharide-based thin films were manufactured by means of subsequent spin-coated deposition of a regenerated cellulose (RC) layer and a 2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO) oxidised cellulose nanofibril (TOCN) layer. The bio-activity of the bilayer was achieved by addition of chitosan (CS). The chitosan was either mixed with the TOCN (TOCN+CS) and deposited on the RC layer by spin-coating, or deposited on the RC and TOCN bilayer by pumping its aqueous solution with various pH over the surface of the bilayer. The water content of the thin films and the CS interactions with the bilayer during deposition were studied in situ by means of a quartz crystal microbalance with dissipation (QCM-D). The pH dependent charging behaviour of the TOCN, TOCN+CS and CS dispersions was evaluated by pH-potentiometric titrations. The surface morphology of the thin films was characterised by atomic force microscopy (AFM). The bio-activity of the thin films was evaluated by studying their protein-repellent properties in situ with a continuous flow of bovine serum albumin (BSA) by means of QCM-D and by evaluating their