Fabrication of PVDF membranes entrapped with oleic acid modified TiO2 and selective adsorption toward bovine hemoglobin

Abstract

An active protein adsorption membrane composed of poly(vinylidenedifluoride) (PVDF) and TiO₂ nanoparticles, which is surface modified by oleic acid (OA) molecules has been fabricated. The hybrid membranes were obtained using an induced phase inversion method by blending the PVDF casting solution and OA-modified TiO₂ nanoparticles. The TiO₂ nanoparticles in the anatase phase with average sizes ranging from 10 to 50 nm were entrapped into the pores and deposited on the surface of PVDF films. Furthermore, the presence of TiO₂ nanoparticles affected the formation process of PVDF films and resulted in the variation of the pore structure of PVDF films. The adsorption performances of these PVDF hybrid membranes were measured using bovine hemoglobin (BHb) and bovine serum albumin (BSA) as target substances, and the effects of adsorption conditions were systematically studied to determine the optimum conditions. The adsorption results showed that the hybrid membranes had significant enhanced adsorption activity toward BHb and BSA in comparison with pure PVDF, and there was a positive relationship between adsorption capacity of proteins and the loading amounts of TiO₂. However, The OA-modification enhanced the BHb adsorption and meanwhile depressed the BSA adsorption. Interestingly, the adsorption capacity of BHb on the hybrid membranes was as 3–4 times that of BSA. Using the mixed protein solution as the adsorption object, the SDS-PAGE analysis demonstrated that BHb can be selectively adsorbed on the hybrid membranes. This work showed a prospective application of these hybrid membranes in the selective adsorption and separation of BHb.