CORRELATION BETWEEN INTERFACIAL FREE-ENERGY AND ALBUMIN ADSORPTION INPOLY(ACRYLONITRILE-ACRYLAMIDE-ACRYLIC ACID) HYDROGELS

An investigation on the influence of chemical compositions and surface properties (e.g., surface free energy in air and hydrogel-water inter facial energy) on the adsorption of bovine serum albumin (BSA) at pH 7 .4 on to a series of poly(acrylonitrile-acrylamide-acrylic acid) hydro gels was carried out. The interfacial energetics were determined from the contact angle data for air-gel and octane-gel in the water environ ment and the specific adsorption of BSA was determined with UV-VIS spe ctroscopy. It is shown that the higher contents of amide and acid grou ps in hydrogel bulk lead to the greater polar component of surface ene rgy in air and the greater BSA adsorption in aqueous solutions. The BS A adsorption decreases with water amount in gels at lower amide/acid c ontents and increases at higher contents. The results imply that the i nterfacial interactions between the protein and the reorganized hydrog el interface in exposure with water, as well as the penetration of pro tein into pores of swollen gels, influence the BSA adsorption. (C) 199 6 John Wiley & Sons, Inc.