Preparation of magnetic metal organic framework nanocomposites for efficient and selective adsorption of hemoglobin from bovine blood

Abstract

We successfully synthesized magnetic metal organic framework nanocomposites by a facile approach. Carboxyl modified magnetic particles (Fe₃O₄–COOH) as the cores were first prepared by a solvothermal method. Then Cu₃(btc)₂ as the shells were fabricated on the surface of Fe₃O₄–COOH by subsequent reactions in ethanol solutions of CuSO₄ and 1,3,5-benzenetricarboxylic acid. The nanocomposites were found to enable efficient and selective adsorption of bovine hemoglobin (BHb) based on an immobilized metal affinity chromatography mechanism. The nanocomposites possessed excellent magnetic responses (57.4 emu g⁻¹) and demonstrated good aqueous dispersibility. They had narrow size distribution and the average size was about 15 nm in diameter. The amount of copper element in Fe₃O₄@[Cu₃(btc)₂] particles was measured to be 2.75%. The Brunauer–Emmett–Teller surface area of Fe₃O₄@[Cu₃(btc)₂] was 95.1 m² g⁻¹. The adsorption kinetic data was well fitted using a pseudo-second-order kinetic model and the adsorption equilibrium can be reached in 90 min. The adsorption isotherm data was well described by the Langmuir equation. More importantly, the nanocomposites displayed superior adsorption capacity for BHb and the maximum adsorption capacity was as high as 6016 mg g⁻¹. Furthermore, the nanocomposites showed high efficiency and good selectivity for isolation of abundant protein BHb from bovine blood. The results demonstrated that Fe₃O₄@[Cu₃(btc)₂] nanocomposites would be a promising affinity material for histidine-rich proteins adsorption.