Adsorption of collagen, serum albumin, and fibronectin to glass and to each other

Abstract The adsorption of calf skin soluble collagen, bovine serum albumin, and human plasma fibronectin to glass and sequentially to each other on glass was studied using change-in-time-of-flow to measure adsorbed film thickness. Irreversibly adsorbed films result in all these cases. The adsorption is path-dependent, i.e., history-dependent, but the results are highly reproducible when the same procedure is followed exactly. Albumin adsorbed to glass tends to give films which grow in proportion to the albumin concentration. Adsorption of collagen to albumin on glass and fibronectin to collagen on glass does not significantly change adsorbed layer thickness. Adsorption of albumin to collagen and collagen to fibronectin increases film thickness, but by much smaller amounts than when these proteins are adsorbed to glass directly. The state of an irreversibly adsorbed protein layer can, thus, only be interpreted on an ad hoc basis, each case for itself, and thermodynamic equilibrium considerations cannot be applied trivially.