Study of β-Lactoglobulin Adsorption on Polyethersulfone Thin Film Surface Using QCM-D and AFM

The adsorption process of β-lactoglobulin on the polyethersulfone-coated surface has been investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), which allowed simultaneous measurements of frequency and energy dissipation changes caused by the formation of a β-lactoglobulin layer during the protein adsorption process. The results showed that the protein adsorption on the spin-coated polyethersulfone surface consisted of reversible and irreversible adsorption processes, and the irreversible adsorption was the principal factor to cause the permanent protein adsorption onto the polymer surface. The amount of irreversible adsorption of β-lactoglobulin increased significantly, from 380.5 ± 23.2 to 745.5 ± 29.7 ng/cm², when the concentration of β-lactoglobulin solution varied from 0.1% to 2.0% (w/v). The pH also played an important role in the protein adsorption. When the pH of the solution varied from 7.0 to 3.0, the amount of irreversible adsorption of β-lactoglobulin increased from 427.1 ± 80.7 to 741.2 ± 135.1 ng/cm².