ADSORPTION OF PROTEINS ON ELECTROCONDUCTIVE POLYMER-FILMS

Shapable electro-conductive (SEC) polymer films (polyanion-doped polyp yrrole films) show several interesting properties for bioelectrochemic al applications. The SEC film can be used as an inert, stable and hydr ophobic electrode in aqueous solution over a wide potential range. In this study, the physical and the potential-assisted adsorption of vari ous proteins on the SEC film is described. Because of the hydrophobic surface characteristic proteins easily adsorb and retain on the film s urface by strong hydrophobic interactions. The amount of the adsorbed protein varies from 2.2 to 4.8 mu g cm(-2) depending on the protein wh en the film is incubated for 22 h in the protein solution. The adsorpt ion is effectively accelerated and enhanced by applying a positive pot ential in the range from 0.4 V to 1.0 V (vs. Ag/AgCl). The potential-a ssisted adsorption process is completed by 10-15 min and the amount of the adsorbed protein is nearly doubled as compared to the adsorption without potential. The adsorbed protein is chemically very stable in c omparison with the protein in solution. More than 85% of the initial a dsorbed proteins retains on the surface after three weeks of incubatio n in buffer solution. The initial adsorption rate is studied by quartz crystal micro-balance measurements on a thin polymer film coated quar tz crystal. In addition, the SEC film surface is etched with air plasm a which leads to a four-fold increase of the adsorption of proteins. ( C) 1997 Elsevier Science S.A.