Adsorption of chitosan on spin-coated cellulose films

This paper reports on the adsorption of an ultrathin chitosan layer on spin-coated films of cellulose, where efficient attachment was induced by oxidizing cellulose which provided anionic sites for electrostatic interaction with the positively charged chitosan. Both the cellulose oxidation and the chitosan adsorption were confirmed with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements. The molecular-level interaction between chitosan and cellulose involved the NH groups, as inferred from the disappearance caused by chitosan adsorption of the amide band at 1667 cm−1 in the FTIR spectrum of cellulose. The XPS data confirmed a significant increase in the atomic concentration of nitrogen groups, from 2.16% to 4.73% when chitosan was adsorbed on the oxidized cellulose film, which also led to rougher films as illustrated by atomic force microscopy images. One may now envisage applications in which the bactericide action of chitosan is combined with the biocompatibility of cellulose.