Bovine serum albumin adsorption and desorption rates on solid surfaces with varying surface properties

Abstract

Total internal reflection fluorescence is used to examine the initial adsorption, desorption, and exchange kinetics of the protein bovine serum albumin (BSA) on six polymer surfaces with widely varying surface properties and functionalities. The six surfaces studied are polydimethylsiloxane (PDMS), polydiphenylsiloxane (PDϕS), polycyanopropylmethylsiloxane (PCPMS), polymethyl methacrylate (PMMA), polystyrene sulfonate (PSS), and polyethylene oxide (PEO). The results show that the initial adsorption of BSA on the surfaces PDMS, PDϕS, and PCPMS is diffusion limited up to wall shear rates of 4000 s−1. The initial adsorption of BSA on PSS is diffusion limited at shear rates below about 70 s−1 but becomes kinetically controlled at higher shear rates. BSA adsorption on PMMA is kinetically controlled, and the adsorption of BSA on PEO is too slow to be detected under the conditions used. Studies on the kinetically limited BSA adsorption onto PMMA show that the adsorption process can be described by a kinetic rate expression that is first order in protein concentration. The initial desorption of BSA adsorbed onto each surface (except PEO) is shown to be kinetically limited. The rate-limiting step for the exchange of BSA adsorbed onto PDMS is shown to be the desorption of adsorbed BSA.