A study on the adsorption of bovine serum albumin onto electrostatic microspheres: Role of surface groups

This article presents an interesting study on the adsorption of bovine serum albumin (BSA) onto electrostatic microspheres. With sulfonated poly(methyl methacrylate) microspheres as the support, the adsorption appears to be sensitive for protein concentration, pH condition and ionic strength. The electrostatic interaction from these sulfonate groups plays obviously an important role in the adsorption, not only increasing the adsorption amount but also affecting the intermolecular interaction of protein. The effect is evidenced by the changes of pH condition and ionic strength. Near the isoelectric point of BSA, the effect reaches a maximum. A higher or lower pH will result in its dramatic decrease. The dependence of protein adsorption on the ionic strength is, however, a cooperative result from the electrostatic interaction and support-protein affinity. With respect to these, further information shows that they can be related to the structure of protein.