Surface modification of chitosan films-grafting ethylene glycol oligomer and its effect on protein adsorption

This work is a part of a series on surface modification of materials made of chitosan. This report focused on grafting monomethoxy ethylene glycol oligomers (mPEG) on the surface of chitosan films. The chemical reactions were performed by immersing the films in organic solvent containing aldehyde derivative of mPEG. The presence of ethylene glycol moieties was determined by attenuated total reflectance-infrared spectroscopy (ATR-IR) and nuclear magnetic resonance (NMR). The hydrophobicity of the modified surface, determined by air-water contact angle, decreased when the ethylene glycol derivatives were grafted on the film. The modified films were also subjected to protein adsorption study in order to assess their uses in biomedical applications. It was found that the presence of ethylene glycol units reduced the adsorption of proteins (albumin and lysozyme) on the films. We therefore have shown that manipulation of the interaction between chitosan and bio-macromolecules is possible by chemically modifying the surface of chitosan.