One-pot synthesis of CuFe2O4 magnetic nanocrystal clusters for highly specific separation of histidine-rich proteins.

This work reports a facile ligand-free method for the rapid and highly specific separation of histidine (His)-rich proteins using CuFe2O4 magnetic nanocrystal clusters (MNCs). Monodispersed CuFe2O4 MNCs were synthesized via a simple and economical one-pot hydrothermal process. The resulting MNCs were characterized in detail. The measurements indicated that the MNCs exhibited good dispersion, high crystallinity, and superparamagnetic properties. Moreover, the obtained MNCs had a high saturation magnetization (45.1 emu g-1), which was sufficient to accomplish fast and efficient separation with an external magnetic field. The selectivity and binding capacity of CuFe2O4 MNCs were evaluated using a His-rich protein (bovine haemoglobin) and other proteins (bovine serum albumin, human serum albumin, myoglobin, lysozyme, cytochrome c and horseradish peroxidase) containing fewer surface-exposed His residues as model samples. The most distinct feature of the CuFe2O4 MNCs is the high haemoglobin binding capacity (4475 mg g-1) due to the coordination between copper(ii) ions and surface-exposed histidine resides of haemoglobin. In addition, the CuFe2O4 MNCs can be successfully employed to selectively bind and remove abundant haemoglobin from human blood samples. The good results demonstrate the potential of CuFe2O4 MNCs in the separation of His-rich proteins.