CHARACTERISTIC PROTEIN ADHESION FORCES ON GLASS AND POLYSTYRENE SUBSTRATES BY ATOMIC-FORCE MICROSCOPY

The force acting between a protein molecule and a nonbiological surfac e is of great importance in biotechnology. We adsorb protein-covered m icrospheres on glass and polystyrene substrates in Tris-buffered salin e. Using a novel atomic force microscopy technique, we show that prote ins adsorb better on hydrophobic than hydrophilic surfaces and that th e microspheres adhere with a force characteristic of the particular pr otein and substrate. The adhesion force on the hydrophobic polystyrene substrate is shown to depend on the structural rigidity of the protei n, while on the hydrophilic glass surface, protein and surface charge is more important.