TEMPERATURE-DEPENDENCE OF BOVINE SERUM-ALBUMIN ADSORPTION ONTO A POLY(ETHYLENE OXIDE)-GRAFTED SURFACE

The adsorption of bovine serum albumin (BSA) onto bare polyethylene (PE) and poly(ethylene oxide)-grafted PE particles was studied by the solution depletion method. Adsorption measurements were performed at different temperatures in the range of 25-65-degrees-C. The PE surface adsorbs high amounts of protein corresponding to a complete side-on monolayer in the temperature range 25-45-degrees-C. The considerable increase in the adsorbed amount and the shape of the isotherms at temperatures above 55-degrees-C indicate surface aggregation approaching the denaturation temperature of BSA. A lower degree of protein adsorption was obtained for PEO-grafted surfaces, and the amount of BSA adsorbed increases continuously with the temperature over the whole range studied. This is in accordance with the changing wettability of the PEO-grafted surface with temperature. The different temperature dependences of the adsorption behaviour found for PE and PEO-grafted surfaces show the joint influence of the protein properties in solution and the surface interactions on the adsorption.