Synthesis of Cu²⁺ Chelated Cellulose/Magnetic Hydroxyapatite Particles Hybrid Beads and Their Potential for High Specific Adsorption of Histidine-Rich Proteins

Abstract

A novel method is described for facile fabrication of immobilized Cu2+ chelated cellulose/magnetic hydroxyapatite hybrid beads (denoted as Cu2+ Cell/MHAP) by an emulsification technique. In this process, the particles of MHAP, as the main component of the adsorbent, were prepared by simply mixing iron oxide with N-(phosphonomethyl)-iminodiacetic acid (PM-IDA) and followed by hydroxyapatite (HAP) deposition in aqueous solution. The obtained MHAP particles were suspended in cellulose solution and emulsified into Cell/MHAP hybrid beads. Finally, chelating Cu2+ on Cell/MHAP through oxygen ions of PO43– groups gave the immobilized metal affinity adsorbent. The combination of immobilized Cu2+ ligands, MHAP particles, and magnetic response together with the large size of the spherical cellulose support endowed the adsorbent with excellent adsorption selectivity, high adsorption capacity, and easy recovery of adsorbent from solvent, respectively. By physical characterization, Cu2+ Cell/MHAP possessed a large specific surface area of 94.2 m2 g–1 and a uniform spherical shape in size of about 137.4 ± 19.5 μm. The adsorption evaluation indicated that Cell/MHAP has a high static adsorption capacity (4533.1 mg g–1) of bovine hemoglobin. Obviously, high adsorption capacity is ascribed to small size and good dispersion of Cu2+ chelated HAP particles in spherical cellulose supports, which provided sufficient specific surface area and suitable volume for protein adsorption. The practical separation potential of Cell/MHAP was evaluated by using diluted bovine blood as a probe, and high adsorption selectivity was confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Together with superparamagnetism, large size, and excellent adsorption performance, the adsorbent of Cell/MHAP has great potential in the field of histidine-rich protein purification.