Dynamic Adsorption of Bovine Serum Albumin Onto Spherical Polyelectrolyte Brushes Triggered By pH

The adsorption of bovine serum albumin (BSA) in spherical poly(acrylic acid) brushes (SPB) was observed by a combination of turbidimetric titration, dynamic light scattering (DLS), zeta potential measurement, UV spectroscopy, and small angle X-ray scattering (SAXS) techniques. Adsorption of BSA onto SPB occurred in the pH range from 7.0 to 4.6 as observed by turbidimetric titration, DLS, and zeta potential measurement. Adsorption, aggregation, and desorption of BSA from SPB were triggered by changing pH. Ionic strength can modulate the extent of the pH regions for adsorption, aggregation, and desorption. The adsorption amount of BSA in SPB was determined by UV spectroscopy, which was dependent on pH and ionic strength. The dynamic adsorption of BSA onto SPB can be controlled through adjusting the pH and ionic strength of the system. The analysis of SPB loaded with BSA by SAXS demonstrated that the protein molecules enter deeply into the brush layer at low ionic strength. The positive charge patches of BSA become multivalent counterions of the poly(acrylic acid) chains grafted on SPB.