A wettability gradient as a tool to study protein adsorption and cell adhesion on polymer surfaces

A new method for preparing a wettability gradient on polymer surfaces was developed. Low density polyethylene sheets were treated in air with corona from a knife-type electrode whose power gradually increases along the same length. The polymer surfaces oxidized gradually with the increasing power and the wettability gradient was created on the surfaces as evidenced by the measurement of water contact angles, Fourier-transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the interactions of model protein and cells in terms of the surface hydrophilicity/hydrophobicity of polymeric materials.