pH-Dependent Adsorption of Human Serum Albumin Protein on a Polystyrene-Block-Poly(acrylic acid)-Coated PVDF Membrane

This study reports the investigation of human serum albumin (HSA) adsorption on a poy-styrene-block-poly(acrylic acid) (PS-b-PAA)-coated PVDF membrane, which is a potential smart material for biomedical applications. First, copolymer coating on the membrane surface was successfully performed, due to the hydrophobic interaction of the PS anchoring group with the PVDF membrane. This was confirmed by Fourier transform infrared spectroscopy (FTIR) characterization of the membrane. Then, HSA adsorption onto the coated membrane was assessed and was proved to be strongly dependent on the pH of the protein solution. Indeed, both FTIR mapping and mass balance calculation using UV-visible spectroscopy displayed a greater HSA adsorption on the membrane at pH 5, even though it still took place at higher pH, but to a lower extent. Afterwards, an ionic strength influence study evinced the role of electrostatic interactions between HSA and the PAA layer on HSA adsorption. Dead-end filtration of HSA through the coated membrane confirmed the pH dependence of HSA adsorption on the coated membrane.