The solution depletion has been used to collect adsorption
isotherms of many different proteins and protein mixtures for
many different surface types embracing a wide range of surface
chemistries and water wetting characteristics [3,14–21].
Results obtained are consistent with that obtained by tensiometry
[22–27] and quartz-crystal microbalance (QCM) [21]. These adsorption
isotherms approximate a Henry isotherm wherein adsorbed
amount is in direct proportion to solution concentration W0
Bi
up
to a maximum solution depletion (Di)max obtained at a particular
solution concentration (W0
Bi
)max at which the adsorbent surface
area is saturated with protein. We have implemented the solution
depletion method using spectroscopy [19,20] for single-protein
solutions or electrophoresis for single- or binary-protein solutions
[3,14–18].