Force measurements on cell repellant and cell adhesive alginic acid coated surfaces

The atomic force microscope (AFM) was used to acquire force versus distance curves between the cantilever tip and samples bearing a surface overlayer of covalently linked alginic acid. The alginic acid coating resists cell-adhesion in in vitro experiments involving a normal and a tumor cell line. However, the surface becomes cell adhesive when alginic acid coated samples are subjected to glow discharge treatment. Force curves show in both cases the typical features resulting from the interaction between the cantilever tip and a hydrophilic, compressible polymer overlayer, suggesting that in both cases a diffuse interface with water exists. Following some recent findings on oligoethyleneglycol-terminated self-assembled-monolayers, it is suggested that conformational and molecular aspects of hydrophilic surface layers, rather than steric repulsion effects, could play a significant role in the mechanism that controls resistance to bio-adhesion.