Competitive plasma protein adsorption on modified polymer surfaces monitored by quartz crystal microbalance technique

This paper describes the effects of photochemical modifications of polymer surfaces on the competitive adsorption of serum proteins and cell adhesion (hepatoma cell line HepG2, L929 fibroblasts and others). The UV modification of polystyrene, poly(methylmethacrylate) and polycarbonate alters the physico-chemical properties of these polymers in a way that allows the formation of micrometer scaled cellular patterns in vitro by controlling the composition and properties of the protein adsorbate. Using a quartz microbalance technique, capable to extract viscoelastic data in addition to the mass load of the polymer coated sensor, we have demonstrated the importance of the thickness and the viscosity of an albumin adsorbate for the observed cell adhesion in vitro. The quantity and viscosity of surface bound albumin on polystyrene, being a cell repellent material in its native state, is lowered when the surface is exposed to UV of lambda = 185 nm in air prior to the contact with albumin solutions or cell culture media. This promotes the deposition of cell adhesion proteins and explains the observed cell patterns. Apart from this special application the described quartz microbalance with dissipation monitoring provides a useful tool for general biocompatibility studies based on surface phenomena of biomaterials.