Adsorption of BSA on the amphiphilic PEG graft copolymer-coated particles

The amphiphilic copolymers comprising several monomethoxy poly( ethylene glycol) ( mPEG) and lauryl side chains were prepared and coated on the polystyrene ( PS) particles to study the interactions between these particles and bovine serum albumin (BSA). The surface mPEG density and mPEG chain length were the primary parameters of interest. A significant fraction of the graft copolymer was washed away from the particle surface during five cycles of centrifugation-dispersion treatment, especially for the one with the smallest number of lauryl side chains. At pH 5, the BSA adsorption data did not follow the Langmuir isotherm model for the graft copolymer-modified particles. This was attributed to the presence of a surface mPEG layer that severely retarded the approach of BSA to the particle. The amount of the adsorbed BSA decreased with increasing the surface mPEG density. A mechanistic model was proposed to qualitatively describe the adsorption of BSA on the mPEG-containing particles and the native particles as well.